update packages

app.py

@@ -1,11 +1,12 @@
 import os
-import spaces
+# import spaces
 
 # install packages for mamba
 def install():
     print("Install personal packages", flush=True)
-    os.system("pip install causal_conv1d-1.0.0-cp310-cp310-linux_x86_64.whl")
-    os.system("pip install mamba_ssm-1.0.1-cp310-cp310-linux_x86_64.whl")
+    # os.system("pip install causal_conv1d-1.0.0-cp310-cp310-linux_x86_64.whl")
+    # os.system("pip install mamba_ssm-1.0.1-cp310-cp310-linux_x86_64.whl")
+    os.system("bash install.sh")
 
 install()
 
@@ -91,7 +92,7 @@ def load_video(video_path):
     return torch_imgs
     
 
-@spaces.GPU
+# @spaces.GPU
 def inference_video(video):
     vid = load_video(video)
     
@@ -110,7 +111,7 @@ def set_example_video(example: list) -> dict:
     return gr.Video.update(value=example[0])
 
 
-@spaces.GPU
+# @spaces.GPU
 def inference_image(img):
     image = img
     image_transform = T.Compose(

causal-conv1d/AUTHORS

@@ -0,0 +1 @@
+Tri Dao, tri@tridao.me

causal-conv1d/LICENSE

@@ -0,0 +1,29 @@
+BSD 3-Clause License
+
+Copyright (c) 2022, the respective contributors, as shown by the AUTHORS file.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of the copyright holder nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

causal-conv1d/README.md

@@ -0,0 +1 @@
+# Causal depthwise conv1d in CUDA with a PyTorch interface

causal-conv1d/causal_conv1d/__init__.py

@@ -0,0 +1,3 @@
+__version__ = "1.0.0"
+
+from causal_conv1d.causal_conv1d_interface import causal_conv1d_fn, causal_conv1d_update

causal-conv1d/causal_conv1d/causal_conv1d_interface.py

@@ -0,0 +1,104 @@
+# Copyright (c) 2023, Tri Dao.
+
+import torch
+import torch.nn.functional as F
+
+
+import causal_conv1d_cuda
+
+
+class CausalConv1dFn(torch.autograd.Function):
+    @staticmethod
+    def forward(ctx, x, weight, bias=None, activation=None):
+        if activation not in [None, "silu", "swish"]:
+            raise NotImplementedError("activation must be None, silu, or swish")
+        if x.stride(2) != 1 and x.stride(1) != 1:
+            x = x.contiguous()
+        bias = bias.contiguous() if bias is not None else None
+        ctx.save_for_backward(x, weight, bias)
+        ctx.activation = activation in ["silu", "swish"]
+        out = causal_conv1d_cuda.causal_conv1d_fwd(x, weight, bias, ctx.activation)
+        return out
+
+    @staticmethod
+    def backward(ctx, dout):
+        x, weight, bias = ctx.saved_tensors
+        if dout.stride(2) != 1 and dout.stride(1) != 1:
+            dout = dout.contiguous()
+        # The kernel supports passing in a pre-allocated dx (e.g., in case we want to fuse the
+        # backward of conv1d with the backward of chunk).
+        # Here we just pass in None and dx will be allocated in the C++ code.
+        dx, dweight, dbias = causal_conv1d_cuda.causal_conv1d_bwd(
+            x, weight, bias, dout, None, ctx.activation
+        )
+        return dx, dweight, dbias if bias is not None else None, None
+
+
+def causal_conv1d_fn(x, weight, bias=None, activation=None):
+    """
+    x: (batch, dim, seqlen)
+    weight: (dim, width)
+    bias: (dim,)
+    activation: either None or "silu" or "swish"
+
+    out: (batch, dim, seqlen)
+    """
+    return CausalConv1dFn.apply(x, weight, bias, activation)
+
+
+def causal_conv1d_ref(x, weight, bias=None, activation=None):
+    """
+    x: (batch, dim, seqlen)
+    weight: (dim, width)
+    bias: (dim,)
+
+    out: (batch, dim, seqlen)
+    """
+    if activation not in [None, "silu", "swish"]:
+        raise NotImplementedError("activation must be None, silu, or swish")
+    dtype_in = x.dtype
+    x = x.to(weight.dtype)
+    seqlen = x.shape[-1]
+    dim, width = weight.shape
+    out = F.conv1d(x, weight.unsqueeze(1), bias, padding=width - 1, groups=dim)
+    out = out[..., :seqlen]
+    return (out if activation is None else F.silu(out)).to(dtype=dtype_in)
+
+
+def causal_conv1d_update(x, conv_state, weight, bias=None, activation=None):
+    """
+    x: (batch, dim)
+    conv_state: (batch, dim, width)
+    weight: (dim, width)
+    bias: (dim,)
+
+    out: (batch, dim)
+    """
+    if activation not in [None, "silu", "swish"]:
+        raise NotImplementedError("activation must be None, silu, or swish")
+    activation = activation in ["silu", "swish"]
+    return causal_conv1d_cuda.causal_conv1d_update(x, conv_state, weight, bias, activation)
+
+
+def causal_conv1d_update_ref(x, conv_state, weight, bias=None, activation=None):
+    """
+    x: (batch, dim)
+    conv_state: (batch, dim, width)
+    weight: (dim, width)
+    bias: (dim,)
+
+    out: (batch, dim)
+    """
+    if activation not in [None, "silu", "swish"]:
+        raise NotImplementedError("activation must be None, silu, or swish")
+    dtype_in = x.dtype
+    batch, dim = x.shape
+    width = weight.shape[1]
+    assert conv_state.shape == (batch, dim, width)
+    assert weight.shape == (dim, width)
+    conv_state.copy_(torch.roll(conv_state, shifts=-1, dims=-1)) # Update state (B D W)
+    conv_state[:, :, -1] = x
+    out = torch.sum(conv_state * weight, dim=-1) # (B D)
+    if bias is not None:
+        out += bias
+    return (out if activation is None else F.silu(out)).to(dtype=dtype_in)

causal-conv1d/csrc/causal_conv1d.cpp

@@ -0,0 +1,333 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#include <ATen/cuda/CUDAContext.h>
+#include <c10/cuda/CUDAGuard.h>
+#include <torch/extension.h>
+#include <vector>
+
+#include "causal_conv1d.h"
+
+#define CHECK_SHAPE(x, ...) TORCH_CHECK(x.sizes() == torch::IntArrayRef({__VA_ARGS__}), #x " must have shape (" #__VA_ARGS__ ")")
+
+#define DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(ITYPE, NAME, ...)                    \
+    if (ITYPE == at::ScalarType::Half) {                                            \
+        using input_t = at::Half;                                                   \
+        __VA_ARGS__();                                                              \
+    } else if (ITYPE == at::ScalarType::BFloat16) {                                 \
+        using input_t = at::BFloat16;                                               \
+        __VA_ARGS__();                                                              \
+    } else if (ITYPE == at::ScalarType::Float)  {                                   \
+        using input_t = float;                                                      \
+        __VA_ARGS__();                                                              \
+    } else {                                                                        \
+        AT_ERROR(#NAME, " not implemented for input type '", toString(ITYPE), "'"); \
+    }
+
+#define DISPATCH_WTYPE_FLOAT_AND_HALF_AND_BF16(WTYPE, NAME, ...)                     \
+    if (WTYPE == at::ScalarType::Half) {                                             \
+        using weight_t = at::Half;                                                   \
+        __VA_ARGS__();                                                               \
+    } else if (WTYPE == at::ScalarType::BFloat16) {                                  \
+        using weight_t = at::BFloat16;                                               \
+        __VA_ARGS__();                                                               \
+    } else if (WTYPE == at::ScalarType::Float)  {                                    \
+        using weight_t = float;                                                      \
+        __VA_ARGS__();                                                               \
+    } else {                                                                         \
+        AT_ERROR(#NAME, " not implemented for weight type '", toString(WTYPE), "'"); \
+    }
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_fwd_cuda(ConvParamsBase &params, cudaStream_t stream);
+template <typename input_t, typename weight_t>
+void causal_conv1d_channellast_fwd_cuda(ConvParamsBase &params, cudaStream_t stream);
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_bwd_cuda(ConvParamsBwd &params, cudaStream_t stream);
+template<typename input_t, typename weight_t>
+void causal_conv1d_channellast_bwd_cuda(ConvParamsBwd &params, cudaStream_t stream);
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_update_cuda(ConvParamsBase &params, cudaStream_t stream);
+
+void set_conv_params_fwd(ConvParamsBase &params,
+                         // sizes
+                         const size_t batch,
+                         const size_t dim,
+                         const size_t seqlen,
+                         const size_t width,
+                         // device pointers
+                         const at::Tensor x,
+                         const at::Tensor weight,
+                         const at::Tensor out,
+                         void* bias_ptr,
+                         bool silu_activation) {
+
+    // Reset the parameters
+    memset(&params, 0, sizeof(params));
+
+    params.batch = batch;
+    params.dim = dim;
+    params.seqlen = seqlen;
+    params.width = width;
+
+    params.silu_activation = silu_activation;
+
+    // Set the pointers and strides.
+    params.x_ptr = x.data_ptr();
+    params.weight_ptr = weight.data_ptr();
+    params.bias_ptr = bias_ptr;
+    params.out_ptr = out.data_ptr();
+    // All stride are in elements, not bytes.
+    params.x_batch_stride = x.stride(0);
+    params.x_c_stride = x.stride(1);
+    params.x_l_stride = x.stride(-1);
+    params.weight_c_stride = weight.stride(0);
+    params.weight_width_stride = weight.stride(1);
+    params.out_batch_stride = out.stride(0);
+    params.out_c_stride = out.stride(1);
+    params.out_l_stride = out.stride(-1);
+}
+
+
+void set_conv_params_bwd(ConvParamsBwd &params,
+                         // sizes
+                         const size_t batch,
+                         const size_t dim,
+                         const size_t seqlen,
+                         const size_t width,
+                         // device pointers
+                         const at::Tensor x,
+                         const at::Tensor weight,
+                         void* bias_ptr,
+                         const at::Tensor dout,
+                         const at::Tensor dx,
+                         const at::Tensor dweight,
+                         void* dbias_ptr,
+                         bool silu_activation) {
+    // Pass in "dout" instead of "out", we're not gonna use "out" at all.
+    set_conv_params_fwd(params, batch, dim, seqlen, width,
+                        x, weight, dout, bias_ptr, silu_activation);
+
+    // Set the pointers and strides.
+    params.dout_ptr = dout.data_ptr();
+    params.dx_ptr = dx.data_ptr();
+    params.dweight_ptr = dweight.data_ptr();
+    params.dbias_ptr = dbias_ptr;
+    // All stride are in elements, not bytes.
+    params.dout_batch_stride = dout.stride(0);
+    params.dout_c_stride = dout.stride(1);
+    params.dout_l_stride = dout.stride(2);
+    params.dweight_c_stride = dweight.stride(0);
+    params.dweight_width_stride = dweight.stride(1);
+    params.dx_batch_stride = dx.stride(0);
+    params.dx_c_stride = dx.stride(1);
+    params.dx_l_stride = dx.stride(2);
+}
+
+at::Tensor
+causal_conv1d_fwd(const at::Tensor &x, const at::Tensor &weight,
+                  const c10::optional<at::Tensor> &bias_,
+                  bool silu_activation) {
+    auto input_type = x.scalar_type();
+    auto weight_type = weight.scalar_type();
+    TORCH_CHECK(input_type == at::ScalarType::Float || input_type == at::ScalarType::Half || input_type == at::ScalarType::BFloat16);
+    TORCH_CHECK(weight_type == at::ScalarType::Float || weight_type == at::ScalarType::Half || weight_type == at::ScalarType::BFloat16);
+
+    TORCH_CHECK(x.is_cuda());
+    TORCH_CHECK(weight.is_cuda());
+
+    const auto sizes = x.sizes();
+    const int batch_size = sizes[0];
+    const int dim = sizes[1];
+    const int seqlen = sizes[2];
+    const int width = weight.size(-1);
+
+    CHECK_SHAPE(x, batch_size, dim, seqlen);
+    CHECK_SHAPE(weight, dim, width);
+
+    TORCH_CHECK(x.stride(2) == 1 || x.stride(1) == 1);
+    const bool is_channel_last = x.stride(1) == 1 && x.stride(2) > 1;
+
+    if (is_channel_last) {
+        TORCH_CHECK(dim % 8 == 0, "causal_conv1d only supports channel dimension divisible by 8 for now");
+    }
+    TORCH_CHECK(width >= 2 && width <= 4, "causal_conv1d only supports width between 2 and 4");
+
+
+    if (bias_.has_value()) {
+        auto bias = bias_.value();
+        TORCH_CHECK(bias.scalar_type() == weight_type);
+        TORCH_CHECK(bias.is_cuda());
+        TORCH_CHECK(bias.stride(-1) == 1);
+        CHECK_SHAPE(bias, dim);
+    }
+
+    at::Tensor out = torch::empty_like(x);
+
+    ConvParamsBase params;
+    set_conv_params_fwd(params, batch_size, dim, seqlen, width, x, weight, out,
+                        bias_.has_value() ? bias_.value().data_ptr() : nullptr,
+                        silu_activation);
+
+    // Otherwise the kernel will be launched from cuda:0 device
+    // Cast to char to avoid compiler warning about narrowing
+    at::cuda::CUDAGuard device_guard{(char)x.get_device()};
+    auto stream = at::cuda::getCurrentCUDAStream().stream();
+    DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(x.scalar_type(), "causal_conv1d_fwd", [&] {
+        DISPATCH_WTYPE_FLOAT_AND_HALF_AND_BF16(weight.scalar_type(), "causal_conv1d_fwd", [&] {
+            if (!is_channel_last) {
+                causal_conv1d_fwd_cuda<input_t, weight_t>(params, stream);
+            } else {
+                causal_conv1d_channellast_fwd_cuda<input_t, weight_t>(params, stream);
+            }
+        });
+    });
+    return out;
+}
+
+std::vector<at::Tensor>
+causal_conv1d_bwd(const at::Tensor &x, const at::Tensor &weight,
+                  const c10::optional<at::Tensor> &bias_,
+                  at::Tensor &dout,
+                  c10::optional<at::Tensor> &dx_,
+                  bool silu_activation) {
+    auto input_type = x.scalar_type();
+    auto weight_type = weight.scalar_type();
+    TORCH_CHECK(input_type == at::ScalarType::Float || input_type == at::ScalarType::Half || input_type == at::ScalarType::BFloat16);
+    TORCH_CHECK(weight_type == at::ScalarType::Float || weight_type == at::ScalarType::Half || weight_type == at::ScalarType::BFloat16);
+
+    TORCH_CHECK(x.is_cuda());
+    TORCH_CHECK(weight.is_cuda());
+    TORCH_CHECK(dout.is_cuda());
+
+    const auto sizes = x.sizes();
+    const int batch_size = sizes[0];
+    const int dim = sizes[1];
+    const int seqlen = sizes[2];
+    const int width = weight.size(-1);
+
+    TORCH_CHECK(width >= 2 && width <= 4, "causal_conv1d only supports width between 2 and 4");
+
+    CHECK_SHAPE(x, batch_size, dim, seqlen);
+    CHECK_SHAPE(weight, dim, width);
+    CHECK_SHAPE(dout, batch_size, dim, seqlen);
+
+    TORCH_CHECK(x.stride(2) == 1 || x.stride(1) == 1);
+    const bool is_channel_last = x.stride(1) == 1 && x.stride(2) > 1;
+    if (!is_channel_last && dout.stride(2) != 1) { dout = dout.contiguous(); }
+    if (is_channel_last && dout.stride(1) != 1) { dout = dout.transpose(-1, -2).contiguous().transpose(-1, -2); }
+
+    if (bias_.has_value()) {
+        auto bias = bias_.value();
+        TORCH_CHECK(bias.scalar_type() == weight_type);
+        TORCH_CHECK(bias.is_cuda());
+        TORCH_CHECK(bias.stride(-1) == 1);
+        CHECK_SHAPE(bias, dim);
+    }
+
+    at::Tensor dx;
+    if (dx_.has_value()) {
+        dx = dx_.value();
+        TORCH_CHECK(dx.scalar_type() == input_type);
+        TORCH_CHECK(dx.is_cuda());
+        CHECK_SHAPE(dx, batch_size, dim, seqlen);
+        if (!is_channel_last) { TORCH_CHECK(dx.stride(2) == 1); }
+        if (is_channel_last) { TORCH_CHECK(dx.stride(1) == 1); }
+    } else {
+        dx = torch::empty_like(x);
+    }
+
+    // Otherwise the kernel will be launched from cuda:0 device
+    // Cast to char to avoid compiler warning about narrowing
+    at::cuda::CUDAGuard device_guard{(char)x.get_device()};
+
+    at::Tensor dweight = torch::zeros_like(weight, weight.options().dtype(at::kFloat));
+    at::Tensor dbias;
+    if (bias_.has_value()) { dbias = torch::zeros_like(bias_.value(), bias_.value().options().dtype(at::kFloat)); }
+
+    ConvParamsBwd params;
+    set_conv_params_bwd(params, batch_size, dim, seqlen, width,
+                        x, weight, bias_.has_value() ? bias_.value().data_ptr() : nullptr,
+                        dout, dx, dweight, bias_.has_value() ? dbias.data_ptr() : nullptr,
+                        silu_activation);
+
+    auto stream = at::cuda::getCurrentCUDAStream().stream();
+    DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(x.scalar_type(), "causal_conv1d_bwd", [&] {
+        DISPATCH_WTYPE_FLOAT_AND_HALF_AND_BF16(weight.scalar_type(), "causal_conv1d_bwd", [&] {
+            if (!is_channel_last) {
+                causal_conv1d_bwd_cuda<input_t, weight_t>(params, stream);
+            } else {
+                causal_conv1d_channellast_bwd_cuda<input_t, weight_t>(params, stream);
+            }
+        });
+    });
+    return {dx, dweight.to(weight.dtype()), bias_.has_value() ? dbias.to(bias_.value().dtype()) : dbias};
+}
+
+at::Tensor
+causal_conv1d_update(const at::Tensor &x,
+                     const at::Tensor &conv_state,
+                     const at::Tensor &weight,
+                     const c10::optional<at::Tensor> &bias_,
+                  bool silu_activation) {
+    auto input_type = x.scalar_type();
+    auto weight_type = weight.scalar_type();
+    TORCH_CHECK(input_type == at::ScalarType::Float || input_type == at::ScalarType::Half || input_type == at::ScalarType::BFloat16);
+    TORCH_CHECK(weight_type == at::ScalarType::Float || weight_type == at::ScalarType::Half || weight_type == at::ScalarType::BFloat16);
+    TORCH_CHECK(conv_state.scalar_type() == input_type);
+
+    TORCH_CHECK(x.is_cuda());
+    TORCH_CHECK(conv_state.is_cuda());
+    TORCH_CHECK(weight.is_cuda());
+
+    const auto sizes = x.sizes();
+    const int batch_size = sizes[0];
+    const int dim = sizes[1];
+    const int width = weight.size(-1);
+
+    CHECK_SHAPE(x, batch_size, dim);
+    CHECK_SHAPE(conv_state, batch_size, dim, width);
+    CHECK_SHAPE(weight, dim, width);
+
+    TORCH_CHECK(width >= 2 && width <= 4, "causal_conv1d only supports width between 2 and 4");
+
+    if (bias_.has_value()) {
+        auto bias = bias_.value();
+        TORCH_CHECK(bias.scalar_type() == weight_type);
+        TORCH_CHECK(bias.is_cuda());
+        TORCH_CHECK(bias.stride(-1) == 1);
+        CHECK_SHAPE(bias, dim);
+    }
+
+    at::Tensor out = torch::empty_like(x);
+
+    ConvParamsBase params;
+    set_conv_params_fwd(params, batch_size, dim, /*seqlen=*/1, width, x, weight, out,
+                        bias_.has_value() ? bias_.value().data_ptr() : nullptr,
+                        silu_activation);
+    params.conv_state_ptr = conv_state.data_ptr();
+    // All stride are in elements, not bytes.
+    params.conv_state_batch_stride = conv_state.stride(0);
+    params.conv_state_c_stride = conv_state.stride(1);
+    params.conv_state_l_stride = conv_state.stride(2);
+
+    // Otherwise the kernel will be launched from cuda:0 device
+    // Cast to char to avoid compiler warning about narrowing
+    at::cuda::CUDAGuard device_guard{(char)x.get_device()};
+    auto stream = at::cuda::getCurrentCUDAStream().stream();
+    DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(x.scalar_type(), "causal_conv1d_update", [&] {
+        DISPATCH_WTYPE_FLOAT_AND_HALF_AND_BF16(weight.scalar_type(), "causal_conv1d_update", [&] {
+            causal_conv1d_update_cuda<input_t, weight_t>(params, stream);
+        });
+    });
+    return out;
+}
+
+PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
+    m.def("causal_conv1d_fwd", &causal_conv1d_fwd, "Causal conv1d forward");
+    m.def("causal_conv1d_bwd", &causal_conv1d_bwd, "Causal conv1d backward");
+    m.def("causal_conv1d_update", &causal_conv1d_update, "Causal conv1d update");
+}

causal-conv1d/csrc/causal_conv1d.h

@@ -0,0 +1,53 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct ConvParamsBase {
+    using index_t = uint32_t;
+
+    int batch, dim, seqlen, width;
+    bool silu_activation;
+
+    index_t x_batch_stride;
+    index_t x_c_stride;
+    index_t x_l_stride;
+    index_t weight_c_stride;
+    index_t weight_width_stride;
+    index_t out_batch_stride;
+    index_t out_c_stride;
+    index_t out_l_stride;
+
+    index_t conv_state_batch_stride;
+    index_t conv_state_c_stride;
+    index_t conv_state_l_stride;
+
+    // Common data pointers.
+    void *__restrict__ x_ptr;
+    void *__restrict__ weight_ptr;
+    void *__restrict__ bias_ptr;
+    void *__restrict__ out_ptr;
+
+    void *__restrict__ conv_state_ptr;
+};
+
+struct ConvParamsBwd: public ConvParamsBase {
+    index_t dx_batch_stride;
+    index_t dx_c_stride;
+    index_t dx_l_stride;
+    index_t dweight_c_stride;
+    index_t dweight_width_stride;
+    index_t dout_batch_stride;
+    index_t dout_c_stride;
+    index_t dout_l_stride;
+
+    // Common data pointers.
+    void *__restrict__ dx_ptr;
+    void *__restrict__ dweight_ptr;
+    void *__restrict__ dbias_ptr;
+    void *__restrict__ dout_ptr;
+};
+

causal-conv1d/csrc/causal_conv1d_bwd.cu

@@ -0,0 +1,525 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#include <c10/util/BFloat16.h>
+#include <c10/util/Half.h>
+#include <c10/cuda/CUDAException.h>  // For C10_CUDA_CHECK and C10_CUDA_KERNEL_LAUNCH_CHECK
+
+#include <cub/block/block_load.cuh>
+#include <cub/block/block_store.cuh>
+#include <cub/block/block_reduce.cuh>
+
+#include "causal_conv1d.h"
+#include "causal_conv1d_common.h"
+#include "static_switch.h"
+
+template<int kNThreads_, int kWidth_, bool kSiluAct_, bool kIsVecLoad_, typename input_t_, typename weight_t_>
+struct Causal_conv1d_bwd_kernel_traits {
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr int kNThreads = kNThreads_;
+    static constexpr int kWidth = kWidth_;
+    static constexpr bool kSiluAct = kSiluAct_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+    static constexpr int kNElts = kNBytes == 4 ? 4 : 8;
+    static_assert(kWidth <= kNElts);
+    // It's possible that we need to do 2 rounds of exchange if input_t is 16 bits
+    // (since then we'd have 8 values of float, and each round we can exchange 4 floats).
+    static constexpr int kNExchangeRounds = sizeof(float) / sizeof(input_t);
+    static constexpr bool kIsVecLoad = kIsVecLoad_;
+    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
+    using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNElts, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadVecT = cub::BlockLoad<vec_t, kNThreads, 1, cub::BLOCK_LOAD_DIRECT>;
+    using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNElts, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    using BlockStoreVecT = cub::BlockStore<vec_t, kNThreads, 1, cub::BLOCK_STORE_DIRECT>;
+    using BlockReduceFloatT = cub::BlockReduce<float, kNThreads>;
+    static constexpr int kSmemIOSize = kIsVecLoad
+        ? 0
+        : std::max({sizeof(typename BlockLoadT::TempStorage), sizeof(typename BlockStoreT::TempStorage)});
+    static constexpr int kSmemExchangeSize = kNThreads * kNBytes * kNElts * (!kSiluAct ? 1 : kNExchangeRounds + 1);
+    static constexpr int kSmemSize = std::max({kSmemExchangeSize,
+            int(sizeof(typename BlockReduceFloatT::TempStorage))}) + (kIsVecLoad ? 0 : kSmemIOSize);
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads)
+void causal_conv1d_bwd_kernel(ConvParamsBwd params) {
+    constexpr int kWidth = Ktraits::kWidth;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    constexpr bool kSiluAct = Ktraits::kSiluAct;
+    constexpr int kNElts = Ktraits::kNElts;
+    constexpr int kNExchangeRounds = Ktraits::kNExchangeRounds;
+    constexpr bool kIsVecLoad = Ktraits::kIsVecLoad;
+    using input_t = typename Ktraits::input_t;
+    using vec_t = typename Ktraits::vec_t;
+    using weight_t = typename Ktraits::weight_t;
+
+    // Shared memory.
+    extern __shared__ char smem_[];
+    auto& smem_load = reinterpret_cast<typename Ktraits::BlockLoadT::TempStorage&>(smem_);
+    auto& smem_load_vec = reinterpret_cast<typename Ktraits::BlockLoadVecT::TempStorage&>(smem_);
+    auto& smem_store = reinterpret_cast<typename Ktraits::BlockStoreT::TempStorage&>(smem_);
+    auto& smem_store_vec = reinterpret_cast<typename Ktraits::BlockStoreVecT::TempStorage&>(smem_);
+    vec_t *smem_exchange = reinterpret_cast<vec_t *>(smem_ + Ktraits::kSmemIOSize);
+    vec_t *smem_exchange_x = reinterpret_cast<vec_t *>(smem_ + Ktraits::kSmemIOSize) + kNThreads * kNExchangeRounds;
+    auto& smem_reduce_float = *reinterpret_cast<typename Ktraits::BlockReduceFloatT::TempStorage*>(smem_ + Ktraits::kSmemIOSize);
+
+    const int tidx = threadIdx.x;
+    const int batch_id = blockIdx.x;
+    const int dim_id = blockIdx.y;
+    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
+        + dim_id * params.x_c_stride;
+    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr) + dim_id * params.weight_c_stride;
+    input_t *dout = reinterpret_cast<input_t *>(params.dout_ptr) + batch_id * params.dout_batch_stride
+        + dim_id * params.dout_c_stride;
+    input_t *dx = reinterpret_cast<input_t *>(params.dx_ptr) + batch_id * params.dx_batch_stride
+        + dim_id * params.dx_c_stride;
+    float *dweight = reinterpret_cast<float *>(params.dweight_ptr) + dim_id * params.dweight_c_stride;
+    float bias_val = params.bias_ptr == nullptr ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[dim_id]);
+
+    // Thread kNThreads - 1 will load the first elements of the next chunk so we initialize those to 0.
+    if (tidx == 0) {
+        if constexpr (!kSiluAct) {
+            input_t zeros[kNElts] = {0};
+            smem_exchange[0] = reinterpret_cast<vec_t *>(zeros)[0];
+        } else {
+            float zeros[kNElts] = {0};
+            #pragma unroll
+            for (int r = 0; r < kNExchangeRounds; ++r) {
+                smem_exchange[r * kNThreads] = reinterpret_cast<vec_t *>(zeros)[r];
+            }
+        }
+    }
+
+    float weight_vals[kWidth];
+    #pragma unroll
+    for (int i = 0; i < kWidth; ++i) { weight_vals[i] = weight[i * params.weight_width_stride]; }
+
+    float dweight_vals[kWidth] = {0};
+    float dbias_val = 0;
+
+    constexpr int kChunkSize = kNThreads * kNElts;
+    const int n_chunks = (params.seqlen + kChunkSize - 1) / kChunkSize;
+    x += (n_chunks - 1) * kChunkSize;
+    dout += (n_chunks - 1) * kChunkSize;
+    dx += (n_chunks - 1) * kChunkSize;
+    for (int chunk = n_chunks - 1; chunk >= 0; --chunk) {
+        input_t x_vals_load[2 * kNElts] = {0};
+        input_t dout_vals_load[2 * kNElts] = {0};
+        if constexpr(kIsVecLoad) {
+            Ktraits::BlockLoadVecT(smem_load_vec).Load(reinterpret_cast<vec_t*>(x), *reinterpret_cast<vec_t (*)[1]>(&x_vals_load[kNElts]), (params.seqlen - chunk * kChunkSize) / kNElts);
+            Ktraits::BlockLoadVecT(smem_load_vec).Load(reinterpret_cast<vec_t*>(dout), *reinterpret_cast<vec_t (*)[1]>(&dout_vals_load[0]), (params.seqlen - chunk * kChunkSize) / kNElts);
+        } else {
+            __syncthreads();
+            Ktraits::BlockLoadT(smem_load).Load(x, *reinterpret_cast<input_t (*)[kNElts]>(&x_vals_load[kNElts]), params.seqlen - chunk * kChunkSize);
+            __syncthreads();
+            Ktraits::BlockLoadT(smem_load).Load(dout, *reinterpret_cast<input_t (*)[kNElts]>(&dout_vals_load[0]), params.seqlen - chunk * kChunkSize);
+        }
+        float dout_vals[2 * kNElts], x_vals[2 * kNElts];
+        if constexpr (!kSiluAct) {
+            __syncthreads();
+            // Thread 0 don't write yet, so that thread kNThreads - 1 can read
+            // the first elements of the next chunk.
+            if (tidx > 0) { smem_exchange[tidx] = reinterpret_cast<vec_t *>(dout_vals_load)[0]; }
+            __syncthreads();
+            reinterpret_cast<vec_t *>(dout_vals_load)[1] = smem_exchange[tidx < kNThreads - 1 ? tidx + 1 : 0];
+            __syncthreads();
+            // Now thread 0 can write the first elements of the current chunk.
+            if (tidx == 0) { smem_exchange[tidx] = reinterpret_cast<vec_t *>(dout_vals_load)[0]; }
+            #pragma unroll
+            for (int i = 0; i < 2 * kNElts; ++i) {
+                dout_vals[i] = float(dout_vals_load[i]);
+                x_vals[i] = float(x_vals_load[i]);
+            }
+        } else {
+            if (tidx == 0 && chunk > 0) {
+                if constexpr(kIsVecLoad) {
+                    reinterpret_cast<vec_t *>(x_vals_load)[0] = reinterpret_cast<vec_t *>(x)[-1];
+                } else {
+                    #pragma unroll
+                    for (int i = 0; i < kNElts; ++i) {
+                        if (chunk * kChunkSize + i < params.seqlen) { x_vals_load[i] = x[-kNElts + i]; }
+                    }
+                }
+            }
+            __syncthreads();
+            smem_exchange_x[tidx] = reinterpret_cast<vec_t *>(x_vals_load)[1];
+            __syncthreads();
+            if (tidx > 0) { reinterpret_cast<vec_t *>(x_vals_load)[0] = smem_exchange_x[tidx - 1]; }
+            #pragma unroll
+            for (int i = 0; i < 2 * kNElts; ++i) { x_vals[i] = float(x_vals_load[i]); }
+            // Recompute the output
+            #pragma unroll
+            for (int i = 0; i < kNElts; ++i) {
+                float out_val = bias_val;
+                #pragma unroll
+                for (int w = 0; w < kWidth; ++w) {
+                    out_val += weight_vals[w] * x_vals[kNElts + i - (kWidth - w - 1)];
+                }
+                float out_sigmoid_val = 1.0f / (1.0f + expf(-out_val));
+                dout_vals[i] = float(dout_vals_load[i]) * out_sigmoid_val
+                               * (1.0f + out_val * (1.0f - out_sigmoid_val));
+            }
+            // Exchange the dout_vals. It's possible that we need to do 2 rounds of exchange
+            // if input_t is 16 bits (since then we'd have 8 values of float)
+            __syncthreads();
+            // Thread 0 don't write yet, so that thread kNThreads - 1 can read
+            // the first elements of the next chunk.
+            if (tidx > 0) {
+                #pragma unroll
+                for (int r = 0; r < kNExchangeRounds; ++r) {
+                    smem_exchange[r * kNThreads + tidx] = reinterpret_cast<vec_t *>(dout_vals)[r];
+                }
+            }
+            __syncthreads();
+            #pragma unroll
+            for (int r = 0; r < kNExchangeRounds; ++r) {
+                reinterpret_cast<vec_t *>(dout_vals)[kNExchangeRounds + r]
+                    = smem_exchange[r * kNThreads + (tidx < kNThreads - 1 ? tidx + 1 : 0)];
+            }
+            __syncthreads();
+            // Now thread 0 can write the first elements of the current chunk.
+            if (tidx == 0) {
+                #pragma unroll
+                for (int r = 0; r < kNExchangeRounds; ++r) {
+                    smem_exchange[r * kNThreads + tidx] = reinterpret_cast<vec_t *>(dout_vals)[r];
+                }
+            }
+        }
+        dout -= kChunkSize;
+        x -= kChunkSize;
+
+        #pragma unroll
+        for (int i = 0; i < kNElts; ++i) { dbias_val += dout_vals[i]; }
+
+        float dx_vals[kNElts] = {0};
+        #pragma unroll
+        for (int i = 0; i < kNElts; ++i) {
+            #pragma unroll
+            for (int w = 0; w < kWidth; ++w) {
+                dx_vals[i] += weight_vals[w] * dout_vals[i + kWidth - w - 1];
+            }
+        }
+
+        input_t dx_vals_store[kNElts];
+        #pragma unroll
+        for (int i = 0; i < kNElts; ++i) { dx_vals_store[i] = dx_vals[i]; }
+        if constexpr(kIsVecLoad) {
+            Ktraits::BlockStoreVecT(smem_store_vec).Store(reinterpret_cast<vec_t*>(dx), reinterpret_cast<vec_t (&)[1]>(dx_vals_store), (params.seqlen - chunk * kChunkSize) / kNElts);
+        } else {
+            Ktraits::BlockStoreT(smem_store).Store(dx, dx_vals_store, params.seqlen - chunk * kChunkSize);
+        }
+        dx -= kChunkSize;
+
+        #pragma unroll
+        for (int w = 0; w < kWidth; ++w) {
+            #pragma unroll
+            for (int i = 0; i < kNElts; ++i) {
+                dweight_vals[w] += x_vals[kNElts + i] * dout_vals[i + kWidth - w - 1];
+            }
+        }
+    }
+
+    #pragma unroll
+    for (int w = 0; w < kWidth; ++w) {
+        __syncthreads();
+        dweight_vals[w] = Ktraits::BlockReduceFloatT(smem_reduce_float).Sum(dweight_vals[w]);
+        if (tidx == 0) {
+            atomicAdd(&reinterpret_cast<float *>(dweight)[w * params.dweight_width_stride], dweight_vals[w]);
+        }
+    }
+    if (params.bias_ptr != nullptr) {
+        __syncthreads();
+        dbias_val = Ktraits::BlockReduceFloatT(smem_reduce_float).Sum(dbias_val);
+        if (tidx == 0) {
+            atomicAdd(&reinterpret_cast<float *>(params.dbias_ptr)[dim_id], dbias_val);
+        }
+    }
+}
+
+template<int kNThreads, int kWidth, typename input_t, typename weight_t>
+void causal_conv1d_bwd_launch(ConvParamsBwd &params, cudaStream_t stream) {
+    static constexpr int kNElts = sizeof(input_t) == 4 ? 4 : 8;
+    BOOL_SWITCH(params.seqlen % kNElts == 0, kIsVecLoad, [&] {
+        BOOL_SWITCH(params.silu_activation, kSiluAct, [&] {
+            using Ktraits = Causal_conv1d_bwd_kernel_traits<kNThreads, kWidth, kSiluAct, kIsVecLoad, input_t, weight_t>;
+            constexpr int kSmemSize = Ktraits::kSmemSize;
+            dim3 grid(params.batch, params.dim);
+            auto kernel = &causal_conv1d_bwd_kernel<Ktraits>;
+            if (kSmemSize >= 48 * 1024) {
+                C10_CUDA_CHECK(cudaFuncSetAttribute(
+                    kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
+                }
+            kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
+            C10_CUDA_KERNEL_LAUNCH_CHECK();
+        });
+    });
+}
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_bwd_cuda(ConvParamsBwd &params, cudaStream_t stream) {
+    if (params.width == 2) {
+        causal_conv1d_bwd_launch<128, 2, input_t, weight_t>(params, stream);
+    } else if (params.width == 3) {
+        causal_conv1d_bwd_launch<128, 3, input_t, weight_t>(params, stream);
+    } else if (params.width == 4) {
+        causal_conv1d_bwd_launch<128, 4, input_t, weight_t>(params, stream);
+    }
+}
+
+template<int kNThreads_, int kWidth_, int kChunkSizeL_, bool kSiluAct_, bool kIsVecLoad_, typename input_t_, typename weight_t_>
+struct Causal_conv1d_channellast_bwd_kernel_traits {
+    // The cache line is 128 bytes, and we try to read 16 bytes per thread.
+    // So we have 8 threads per "row", so 32 or 64 elements in the channel dimension.
+    // That leaves 4 columns per warp, and so 16 columns per block (assuming each block has 128
+    // threads). Each each load is 16 x 32|64 elements in the L x C dimensions.
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr bool kSiluAct = kSiluAct_;
+    static constexpr int kNThreads = kNThreads_;
+    static_assert(kNThreads % 32 == 0);
+    static constexpr int kNWarps = kNThreads / 32;
+    static constexpr int kWidth = kWidth_;
+    static constexpr int kChunkSizeL = kChunkSizeL_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+    static constexpr int kNElts = kNBytes == 4 ? 4 : 8;
+    static constexpr int kNEltsPerRow = 128 / kNBytes;
+    static constexpr int kNThreadsPerRow = kNEltsPerRow / kNElts;  // Always 8 for now
+    static_assert(kNThreadsPerRow * kNBytes * kNElts == 128);
+    static constexpr int kNColsPerWarp = 32 / kNThreadsPerRow;  // Always 4 for now
+    static_assert(kNColsPerWarp * kNThreadsPerRow == 32);
+    static constexpr int kNColsPerLoad = kNColsPerWarp * kNWarps;
+    static constexpr int kNLoads = kChunkSizeL / kNColsPerLoad;
+    static_assert(kNLoads * kNColsPerLoad == kChunkSizeL);
+    static constexpr bool kIsVecLoad = kIsVecLoad_;
+    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
+    // using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNItems, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    // using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNItems, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    // static constexpr int kSmemSize = std::max({sizeof(typename BlockLoadT::TempStorage),
+    //                                            sizeof(typename BlockStoreT::TempStorage)});
+    // static constexpr int kSmemSize = kChunkSizeL * kNEltsPerRow * kNBytes;
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads)
+void causal_conv1d_channellast_bwd_kernel(ConvParamsBwd params) {
+    constexpr int kWidth = Ktraits::kWidth;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    constexpr bool kSiluAct = Ktraits::kSiluAct;
+    constexpr int kNElts = Ktraits::kNElts;
+    constexpr int kNWarp = Ktraits::kNWarps;
+    constexpr int kNThreadsPerC = Ktraits::kNThreadsPerRow;
+    constexpr int kLPerLoad = Ktraits::kNColsPerLoad;
+    constexpr int kChunkSizeL = Ktraits::kChunkSizeL;
+    constexpr int kChunkSizeC = Ktraits::kNEltsPerRow;
+    using input_t = typename Ktraits::input_t;
+    using vec_t = typename Ktraits::vec_t;
+    using weight_t = typename Ktraits::weight_t;
+
+    // Shared memory.
+    __shared__ input_t dout_smem[kChunkSizeL + kWidth - 1][kChunkSizeC + kNElts];
+    __shared__ input_t x_smem[kWidth - 1 + kChunkSizeL + kWidth - 1][kChunkSizeC + kNElts];
+
+    const int tid = threadIdx.x;
+    const int l_idx = tid / kNThreadsPerC;
+    const int c_idx = tid % kNThreadsPerC;
+    const int batch_id = blockIdx.x;
+    const int chunk_l_id = blockIdx.y;
+    const int chunk_c_id = blockIdx.z;
+    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
+        + (chunk_l_id * kChunkSizeL + l_idx) * params.x_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;
+    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr)
+        + chunk_c_id * kChunkSizeC * params.weight_c_stride;
+    input_t *dout = reinterpret_cast<input_t *>(params.dout_ptr) + batch_id * params.dout_batch_stride
+        + (chunk_l_id * kChunkSizeL + l_idx) * params.dout_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;
+    input_t *dx = reinterpret_cast<input_t *>(params.dx_ptr) + batch_id * params.dx_batch_stride
+        + (chunk_l_id * kChunkSizeL + l_idx) * params.dx_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;
+    float *dweight = reinterpret_cast<float *>(params.dweight_ptr)
+        + chunk_c_id * kChunkSizeC * params.dweight_c_stride;
+
+    #pragma unroll
+    for (int l = 0; l < Ktraits::kNLoads; ++l) {
+        input_t dout_vals_load[kNElts] = {0};
+        input_t x_vals_load[kNElts] = {0};
+        if (chunk_l_id * kChunkSizeL + l * kLPerLoad + l_idx < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            reinterpret_cast<vec_t *>(dout_vals_load)[0] = *reinterpret_cast<vec_t *>(dout + l * kLPerLoad * params.dout_l_stride);
+            reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x + l * kLPerLoad * params.x_l_stride);
+        }
+        reinterpret_cast<vec_t *>(dout_smem[l * kLPerLoad + l_idx])[c_idx] = reinterpret_cast<vec_t *>(dout_vals_load)[0];
+        reinterpret_cast<vec_t *>(x_smem[kWidth - 1 + l * kLPerLoad + l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
+    }
+    // Load the elements from the previous chunk or next chunk that are needed for convolution.
+    if (l_idx < kWidth - 1) {
+        input_t dout_vals_load[kNElts] = {0};
+        input_t x_vals_load[kNElts] = {0};
+        if ((chunk_l_id + 1) * kChunkSizeL + l_idx < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            reinterpret_cast<vec_t *>(dout_vals_load)[0] = *reinterpret_cast<vec_t *>(dout + kChunkSizeL * params.dout_l_stride);
+        }
+        if (chunk_l_id * kChunkSizeL + l_idx - (kWidth - 1) >= 0
+            && chunk_l_id * kChunkSizeL + l_idx - (kWidth - 1) < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x - (kWidth - 1) * params.x_l_stride);
+        }
+        reinterpret_cast<vec_t *>(dout_smem[kChunkSizeL + l_idx])[c_idx] = reinterpret_cast<vec_t *>(dout_vals_load)[0];
+        reinterpret_cast<vec_t *>(x_smem[l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
+    }
+    // Need to load (kWdith - 1) extra x's on the right to recompute the (kChunkSizeL + kWidth - 1) outputs
+    if constexpr (kSiluAct) {
+        if (l_idx < kWidth - 1) {
+            input_t x_vals_load[kNElts] = {0};
+            if ((chunk_l_id + 1) * kChunkSizeL + l_idx < params.seqlen
+                && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+                reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x + kChunkSizeL * params.x_l_stride);
+            }
+            reinterpret_cast<vec_t *>(x_smem[kWidth - 1 + kChunkSizeL + l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
+        }
+    }
+
+    __syncthreads();
+
+    constexpr int kLPerThread = std::min(kChunkSizeL * kChunkSizeC / kNThreads, kChunkSizeL);
+    static_assert(kLPerThread * kNThreads == kChunkSizeL * kChunkSizeC);
+    constexpr int kNThreadsPerRow = kChunkSizeL / kLPerThread;
+    static_assert(kNThreadsPerRow * kLPerThread == kChunkSizeL);
+    // kChunkSizeL, kLPerThread, kNThreadsPerRow should be powers of 2 for simplicity
+    static_assert((kChunkSizeL & (kChunkSizeL - 1)) == 0);
+    static_assert((kLPerThread & (kLPerThread - 1)) == 0);
+    static_assert((kNThreadsPerRow & (kNThreadsPerRow - 1)) == 0);
+    static_assert(kNThreadsPerRow <= 32);
+
+    const int row_idx = tid / kNThreadsPerRow;
+    const int col_idx = tid % kNThreadsPerRow;
+
+    float bias_val = params.bias_ptr == nullptr || chunk_c_id * kChunkSizeC + row_idx >= params.dim ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[chunk_c_id * kChunkSizeC + row_idx]);
+    float weight_vals[kWidth] = {0};
+    if (chunk_c_id * kChunkSizeC + row_idx < params.dim) {
+        #pragma unroll
+        for (int w = 0; w < kWidth; ++w) {
+            weight_vals[w] = weight[row_idx * params.weight_c_stride + w * params.weight_width_stride];
+        }
+    }
+    float dout_vals[kLPerThread + kWidth - 1];
+    float x_vals[kWidth - 1 + kLPerThread + kWidth - 1];
+    #pragma unroll
+    for (int i = 0; i < kWidth - 1 + kLPerThread; ++i) {
+        dout_vals[i] = float(dout_smem[col_idx * kLPerThread + i][row_idx]);
+        x_vals[i] = float(x_smem[col_idx * kLPerThread + i][row_idx]);
+    }
+
+    if constexpr (kSiluAct) {  // Recompute the output
+        #pragma unroll
+        for (int i = kWidth - 1 + kLPerThread; i < kWidth - 1 + kLPerThread + kWidth - 1; ++i) {
+            x_vals[i] = float(x_smem[col_idx * kLPerThread + i][row_idx]);
+        }
+        #pragma unroll
+        for (int i = 0; i < kLPerThread + kWidth - 1; ++i) {
+            float out_val = bias_val;
+            #pragma unroll
+            for (int w = 0; w < kWidth; ++w) { out_val += weight_vals[w] * x_vals[i + w]; }
+            float out_val_sigmoid = 1.f / (1.f + expf(-out_val));
+            dout_vals[i] *= out_val_sigmoid * (1 + out_val * (1 - out_val_sigmoid));
+        }
+    }
+
+    float dweight_vals[kWidth] = {0};
+    SumOp<float> sum_op;
+    #pragma unroll
+    for (int w = 0; w < kWidth; ++w) {
+        #pragma unroll
+        for (int i = 0; i < kLPerThread; ++i) { dweight_vals[w] += x_vals[i + w] * dout_vals[i]; }
+        dweight_vals[w] = Allreduce<kNThreadsPerRow>::run(dweight_vals[w], sum_op);
+        if (col_idx == 0 && chunk_c_id * kChunkSizeC + row_idx < params.dim) {
+            atomicAdd(&reinterpret_cast<float *>(dweight)[row_idx * params.dweight_c_stride + w * params.dweight_width_stride], dweight_vals[w]);
+        }
+    }
+
+    if (params.bias_ptr != nullptr) {
+        float dbias_val = 0.f;
+        for (int i = 0; i < kLPerThread; ++i) { dbias_val += dout_vals[i]; }
+        dbias_val = Allreduce<kNThreadsPerRow>::run(dbias_val, sum_op);
+        if (col_idx == 0 && chunk_c_id * kChunkSizeC + row_idx < params.dim) {
+            atomicAdd(&reinterpret_cast<float *>(params.dbias_ptr)[chunk_c_id * kChunkSizeC + row_idx], dbias_val);
+        }
+    }
+
+    float dx_vals[kLPerThread] = {0};
+    #pragma unroll
+    for (int i = 0; i < kLPerThread; ++i) {
+        #pragma unroll
+        for (int w = 0; w < kWidth; ++w) { dx_vals[i] += weight_vals[kWidth - 1 - w] * dout_vals[i + w]; }
+    }
+    // Since kNThreadsPerRow is a power of 2 and <= 32, we only need syncwarp and not syncthreads.
+    __syncwarp();
+    #pragma unroll
+    for (int i = 0; i < kLPerThread; ++i) { x_smem[col_idx * kLPerThread + i][row_idx] = dx_vals[i]; }
+    __syncthreads();
+
+    #pragma unroll
+    for (int l = 0; l < Ktraits::kNLoads; ++l) {
+        input_t dx_vals_store[kNElts];
+        reinterpret_cast<vec_t *>(dx_vals_store)[0] = reinterpret_cast<vec_t *>(x_smem[l * kLPerLoad + l_idx])[c_idx];
+        if (chunk_l_id * kChunkSizeL + l * kLPerLoad + l_idx < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            *reinterpret_cast<vec_t *>(dx + l * kLPerLoad * params.dx_l_stride) = reinterpret_cast<vec_t *>(dx_vals_store)[0];
+        }
+    }
+
+}
+
+template<int kNThreads, int kWidth, typename input_t, typename weight_t>
+void causal_conv1d_channellast_bwd_launch(ConvParamsBwd &params, cudaStream_t stream) {
+    BOOL_SWITCH(params.silu_activation, kSiluAct, [&] {
+        using Ktraits = Causal_conv1d_channellast_bwd_kernel_traits<kNThreads, kWidth, 64, kSiluAct, true, input_t, weight_t>;
+        // constexpr int kSmemSize = Ktraits::kSmemSize;
+        constexpr int kChunkSizeL = Ktraits::kChunkSizeL;
+        constexpr int kChunkSizeC = Ktraits::kNEltsPerRow;
+        const int n_chunks_L = (params.seqlen + kChunkSizeL - 1) / kChunkSizeL;
+        const int n_chunks_C = (params.dim + kChunkSizeC - 1) / kChunkSizeC;
+        dim3 grid(params.batch, n_chunks_L, n_chunks_C);
+        dim3 block(Ktraits::kNThreads);
+        auto kernel = &causal_conv1d_channellast_bwd_kernel<Ktraits>;
+        // if (kSmemSize >= 48 * 1024) {
+        //     C10_CUDA_CHECK(cudaFuncSetAttribute(
+        //         kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
+        //     }
+        // kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
+        kernel<<<grid, Ktraits::kNThreads, 0, stream>>>(params);
+        C10_CUDA_KERNEL_LAUNCH_CHECK();
+    });
+}
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_channellast_bwd_cuda(ConvParamsBwd &params, cudaStream_t stream) {
+    if (params.width == 2) {
+        causal_conv1d_channellast_bwd_launch<128, 2, input_t, weight_t>(params, stream);
+    } else if (params.width == 3) {
+        causal_conv1d_channellast_bwd_launch<128, 3, input_t, weight_t>(params, stream);
+    } else if (params.width == 4) {
+        causal_conv1d_channellast_bwd_launch<128, 4, input_t, weight_t>(params, stream);
+    }
+}
+
+template void causal_conv1d_bwd_cuda<float, float>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<at::Half, float>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<at::BFloat16, float>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<float, at::Half>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<at::Half, at::Half>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<at::BFloat16, at::Half>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<float, at::BFloat16>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<at::Half, at::BFloat16>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_bwd_cuda<at::BFloat16, at::BFloat16>(ConvParamsBwd &params, cudaStream_t stream);
+
+template void causal_conv1d_channellast_bwd_cuda<float, float>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<at::Half, float>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<at::BFloat16, float>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<float, at::Half>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<at::Half, at::Half>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<at::BFloat16, at::Half>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<float, at::BFloat16>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<at::Half, at::BFloat16>(ConvParamsBwd &params, cudaStream_t stream);
+template void causal_conv1d_channellast_bwd_cuda<at::BFloat16, at::BFloat16>(ConvParamsBwd &params, cudaStream_t stream);

causal-conv1d/csrc/causal_conv1d_common.h

@@ -0,0 +1,64 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+#include <cuda_bf16.h>
+#include <cuda_fp16.h>
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<int BYTES> struct BytesToType {};
+
+template<> struct BytesToType<16> {
+    using Type = uint4;
+    static_assert(sizeof(Type) == 16);
+};
+
+template<> struct BytesToType<8> {
+    using Type = uint64_t;
+    static_assert(sizeof(Type) == 8);
+};
+
+template<> struct BytesToType<4> {
+    using Type = uint32_t;
+    static_assert(sizeof(Type) == 4);
+};
+
+template<> struct BytesToType<2> {
+    using Type = uint16_t;
+    static_assert(sizeof(Type) == 2);
+};
+
+template<> struct BytesToType<1> {
+    using Type = uint8_t;
+    static_assert(sizeof(Type) == 1);
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<typename T>
+struct SumOp {
+__device__ inline T operator()(T const & x, T const & y) { return x + y; }
+};
+
+template<int THREADS>
+struct Allreduce {
+    static_assert(THREADS == 32 || THREADS == 16 || THREADS == 8 || THREADS == 4);
+    template<typename T, typename Operator>
+    static __device__ inline T run(T x, Operator &op) {
+        constexpr int OFFSET = THREADS / 2;
+        x = op(x, __shfl_xor_sync(uint32_t(-1), x, OFFSET));
+        return Allreduce<OFFSET>::run(x, op);
+    }
+};
+
+template<>
+struct Allreduce<2> {
+template<typename T, typename Operator>
+static __device__ inline T run(T x, Operator &op) {
+    x = op(x, __shfl_xor_sync(uint32_t(-1), x, 1));
+    return x;
+}
+};

causal-conv1d/csrc/causal_conv1d_fwd.cu

@@ -0,0 +1,350 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#include <c10/util/BFloat16.h>
+#include <c10/util/Half.h>
+#include <c10/cuda/CUDAException.h>  // For C10_CUDA_CHECK and C10_CUDA_KERNEL_LAUNCH_CHECK
+
+#include <cub/block/block_load.cuh>
+#include <cub/block/block_store.cuh>
+
+#include "causal_conv1d.h"
+#include "causal_conv1d_common.h"
+#include "static_switch.h"
+
+template<int kNThreads_, int kWidth_, bool kIsVecLoad_, typename input_t_, typename weight_t_>
+struct Causal_conv1d_fwd_kernel_traits {
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr int kNThreads = kNThreads_;
+    static constexpr int kWidth = kWidth_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+    static constexpr int kNElts = kNBytes == 4 ? 4 : 8;
+    static_assert(kWidth <= kNElts);
+    static constexpr bool kIsVecLoad = kIsVecLoad_;
+    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
+    using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNElts, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadVecT = cub::BlockLoad<vec_t, kNThreads, 1, cub::BLOCK_LOAD_DIRECT>;
+    using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNElts, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    using BlockStoreVecT = cub::BlockStore<vec_t, kNThreads, 1, cub::BLOCK_STORE_DIRECT>;
+    static constexpr int kSmemIOSize = kIsVecLoad
+        ? 0
+        : std::max({sizeof(typename BlockLoadT::TempStorage), sizeof(typename BlockStoreT::TempStorage)});
+    static constexpr int kSmemExchangeSize = kNThreads * kNBytes * kNElts;
+    static constexpr int kSmemSize = kSmemIOSize + kSmemExchangeSize;
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads)
+void causal_conv1d_fwd_kernel(ConvParamsBase params) {
+    constexpr int kWidth = Ktraits::kWidth;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    constexpr int kNElts = Ktraits::kNElts;
+    constexpr bool kIsVecLoad = Ktraits::kIsVecLoad;
+    using input_t = typename Ktraits::input_t;
+    using vec_t = typename Ktraits::vec_t;
+    using weight_t = typename Ktraits::weight_t;
+
+    // Shared memory.
+    extern __shared__ char smem_[];
+    auto& smem_load = reinterpret_cast<typename Ktraits::BlockLoadT::TempStorage&>(smem_);
+    auto& smem_load_vec = reinterpret_cast<typename Ktraits::BlockLoadVecT::TempStorage&>(smem_);
+    auto& smem_store = reinterpret_cast<typename Ktraits::BlockStoreT::TempStorage&>(smem_);
+    auto& smem_store_vec = reinterpret_cast<typename Ktraits::BlockStoreVecT::TempStorage&>(smem_);
+    vec_t *smem_exchange = reinterpret_cast<vec_t *>(smem_ + Ktraits::kSmemIOSize);
+
+    const int tidx = threadIdx.x;
+    const int batch_id = blockIdx.x;
+    const int channel_id = blockIdx.y;
+    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
+        + channel_id * params.x_c_stride;
+    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr) + channel_id * params.weight_c_stride;
+    input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
+        + channel_id * params.out_c_stride;
+    float bias_val = params.bias_ptr == nullptr ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[channel_id]);
+
+    // Thread 0 will load the last elements of the previous chunk, so we initialize those to 0.
+    if (tidx == 0) {
+        input_t zeros[kNElts] = {0};
+        smem_exchange[kNThreads - 1] = reinterpret_cast<vec_t *>(zeros)[0];
+    }
+
+    float weight_vals[kWidth];
+    #pragma unroll
+    for (int i = 0; i < kWidth; ++i) { weight_vals[i] = float(weight[i * params.weight_width_stride]); }
+
+    constexpr int kChunkSize = kNThreads * kNElts;
+    const int n_chunks = (params.seqlen + kChunkSize - 1) / kChunkSize;
+    for (int chunk = 0; chunk < n_chunks; ++chunk) {
+        input_t x_vals_load[2 * kNElts] = {0};
+        if constexpr(kIsVecLoad) {
+            Ktraits::BlockLoadVecT(smem_load_vec).Load(reinterpret_cast<vec_t*>(x), *reinterpret_cast<vec_t (*)[1]>(&x_vals_load[kNElts]), (params.seqlen - chunk * kChunkSize) / kNElts);
+        } else {
+            __syncthreads();
+            Ktraits::BlockLoadT(smem_load).Load(x, *reinterpret_cast<input_t (*)[kNElts]>(&x_vals_load[kNElts]), params.seqlen - chunk * kChunkSize);
+        }
+        x += kChunkSize;
+        __syncthreads();
+        // Thread kNThreads - 1 don't write yet, so that thread 0 can read
+        // the last elements of the previous chunk.
+        if (tidx < kNThreads - 1) { smem_exchange[tidx] = reinterpret_cast<vec_t *>(x_vals_load)[1]; }
+        __syncthreads();
+        reinterpret_cast<vec_t *>(x_vals_load)[0] = smem_exchange[tidx > 0 ? tidx - 1 : kNThreads - 1];
+        __syncthreads();
+        // Now thread kNThreads - 1 can write the last elements of the current chunk.
+        if (tidx == kNThreads - 1) { smem_exchange[tidx] = reinterpret_cast<vec_t *>(x_vals_load)[1]; }
+
+        float x_vals[2 * kNElts];
+        #pragma unroll
+        for (int i = 0; i < 2 * kNElts; ++i) { x_vals[i] = float(x_vals_load[i]); }
+
+        float out_vals[kNElts];
+        #pragma unroll
+        for (int i = 0; i < kNElts; ++i) {
+            out_vals[i] = bias_val;
+            #pragma unroll
+            for (int w = 0; w < kWidth; ++w) {
+                out_vals[i] += weight_vals[w] * x_vals[kNElts + i - (kWidth - w - 1)];
+            }
+        }
+
+        if (params.silu_activation) {
+            #pragma unroll
+            for (int i = 0; i < kNElts; ++i) {
+                out_vals[i] = out_vals[i] / (1 + expf(-out_vals[i]));
+            }
+        }
+
+        input_t out_vals_store[kNElts];
+        #pragma unroll
+        for (int i = 0; i < kNElts; ++i) { out_vals_store[i] = out_vals[i]; }
+        if constexpr(kIsVecLoad) {
+            Ktraits::BlockStoreVecT(smem_store_vec).Store(reinterpret_cast<vec_t*>(out), reinterpret_cast<vec_t (&)[1]>(out_vals_store), (params.seqlen - chunk * kChunkSize) / kNElts);
+        } else {
+            Ktraits::BlockStoreT(smem_store).Store(out, out_vals_store, params.seqlen - chunk * kChunkSize);
+        }
+        out += kChunkSize;
+    }
+}
+
+template<int kNThreads, int kWidth, typename input_t, typename weight_t>
+void causal_conv1d_fwd_launch(ConvParamsBase &params, cudaStream_t stream) {
+    static constexpr int kNElts = sizeof(input_t) == 4 ? 4 : 8;
+    BOOL_SWITCH(params.seqlen % kNElts == 0, kIsVecLoad, [&] {
+        using Ktraits = Causal_conv1d_fwd_kernel_traits<kNThreads, kWidth, kIsVecLoad, input_t, weight_t>;
+        constexpr int kSmemSize = Ktraits::kSmemSize;
+        dim3 grid(params.batch, params.dim);
+        auto kernel = &causal_conv1d_fwd_kernel<Ktraits>;
+        if (kSmemSize >= 48 * 1024) {
+            C10_CUDA_CHECK(cudaFuncSetAttribute(
+                kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
+            }
+        kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
+        C10_CUDA_KERNEL_LAUNCH_CHECK();
+    });
+}
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_fwd_cuda(ConvParamsBase &params, cudaStream_t stream) {
+    if (params.width == 2) {
+        causal_conv1d_fwd_launch<128, 2, input_t, weight_t>(params, stream);
+    } else if (params.width == 3) {
+        causal_conv1d_fwd_launch<128, 3, input_t, weight_t>(params, stream);
+    } else if (params.width == 4) {
+        causal_conv1d_fwd_launch<128, 4, input_t, weight_t>(params, stream);
+    }
+}
+
+template<int kNThreads_, int kWidth_, int kChunkSizeL_, bool kIsVecLoad_, typename input_t_, typename weight_t_>
+struct Causal_conv1d_channellast_fwd_kernel_traits {
+    // The cache line is 128 bytes, and we try to read 16 bytes per thread.
+    // So we have 8 threads per "row", so 32 or 64 elements in the channel dimension.
+    // That leaves 4 columns per warp, and so 16 columns per block (assuming each block has 128
+    // threads). Each each load is 16 x 32|64 elements in the L x C dimensions.
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr int kNThreads = kNThreads_;
+    static_assert(kNThreads % 32 == 0);
+    static constexpr int kNWarps = kNThreads / 32;
+    static constexpr int kWidth = kWidth_;
+    static constexpr int kChunkSizeL = kChunkSizeL_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+    static constexpr int kNElts = kNBytes == 4 ? 4 : 8;
+    static constexpr int kNEltsPerRow = 128 / kNBytes;
+    static constexpr int kNThreadsPerRow = kNEltsPerRow / kNElts;  // Always 8 for now
+    static_assert(kNThreadsPerRow * kNBytes * kNElts == 128);
+    static constexpr int kNColsPerWarp = 32 / kNThreadsPerRow;  // Always 4 for now
+    static_assert(kNColsPerWarp * kNThreadsPerRow == 32);
+    static constexpr int kNColsPerLoad = kNColsPerWarp * kNWarps;
+    static constexpr int kNLoads = kChunkSizeL / kNColsPerLoad;
+    static_assert(kNLoads * kNColsPerLoad == kChunkSizeL);
+    static constexpr bool kIsVecLoad = kIsVecLoad_;
+    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
+    // using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNItems, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    // using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNItems, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    // static constexpr int kSmemSize = std::max({sizeof(typename BlockLoadT::TempStorage),
+    //                                            sizeof(typename BlockStoreT::TempStorage)});
+    // static constexpr int kSmemSize = kChunkSizeL * kNEltsPerRow * kNBytes;
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads)
+void causal_conv1d_channellast_fwd_kernel(ConvParamsBase params) {
+    constexpr int kWidth = Ktraits::kWidth;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    constexpr int kNElts = Ktraits::kNElts;
+    constexpr int kNWarp = Ktraits::kNWarps;
+    constexpr int kNThreadsPerC = Ktraits::kNThreadsPerRow;
+    constexpr int kLPerLoad = Ktraits::kNColsPerLoad;
+    constexpr int kChunkSizeL = Ktraits::kChunkSizeL;
+    constexpr int kChunkSizeC = Ktraits::kNEltsPerRow;
+    using input_t = typename Ktraits::input_t;
+    using vec_t = typename Ktraits::vec_t;
+    using weight_t = typename Ktraits::weight_t;
+
+    // Shared memory.
+    __shared__ input_t x_smem[kWidth - 1 + kChunkSizeL][kChunkSizeC + kNElts];
+
+    const int tid = threadIdx.x;
+    const int l_idx = tid / kNThreadsPerC;
+    const int c_idx = tid % kNThreadsPerC;
+    const int batch_id = blockIdx.x;
+    const int chunk_l_id = blockIdx.y;
+    const int chunk_c_id = blockIdx.z;
+    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
+        + (chunk_l_id * kChunkSizeL + l_idx) * params.x_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;
+    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr)
+        + chunk_c_id * kChunkSizeC * params.weight_c_stride;
+    input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
+        + (chunk_l_id * kChunkSizeL + l_idx) * params.out_l_stride + chunk_c_id * kChunkSizeC + c_idx * kNElts;
+
+    #pragma unroll
+    for (int l = 0; l < Ktraits::kNLoads; ++l) {
+        input_t x_vals_load[kNElts] = {0};
+        if (chunk_l_id * kChunkSizeL + l * kLPerLoad + l_idx < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x + l * kLPerLoad * params.x_l_stride);
+        }
+        reinterpret_cast<vec_t *>(x_smem[kWidth - 1 + l * kLPerLoad + l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
+    }
+    // Load the elements from the previous chunk that are needed for convolution.
+    if (l_idx < kWidth - 1) {
+        input_t x_vals_load[kNElts] = {0};
+        if (chunk_l_id * kChunkSizeL + l_idx - (kWidth - 1) >= 0
+            && chunk_l_id * kChunkSizeL + l_idx - (kWidth - 1) < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            reinterpret_cast<vec_t *>(x_vals_load)[0] = *reinterpret_cast<vec_t *>(x - (kWidth - 1) * params.x_l_stride);
+        }
+        reinterpret_cast<vec_t *>(x_smem[l_idx])[c_idx] = reinterpret_cast<vec_t *>(x_vals_load)[0];
+    }
+
+    __syncthreads();
+
+    constexpr int kLPerThread = std::min(kChunkSizeL * kChunkSizeC / kNThreads, kChunkSizeL);
+    static_assert(kLPerThread * kNThreads == kChunkSizeL * kChunkSizeC);
+    constexpr int kNThreadsPerRow = kChunkSizeL / kLPerThread;
+    static_assert(kNThreadsPerRow * kLPerThread == kChunkSizeL);
+    // kChunkSizeL, kLPerThread, kNThreadsPerRow should be powers of 2 for simplicity
+    static_assert((kChunkSizeL & (kChunkSizeL - 1)) == 0);
+    static_assert((kLPerThread & (kLPerThread - 1)) == 0);
+    static_assert((kNThreadsPerRow & (kNThreadsPerRow - 1)) == 0);
+    static_assert(kNThreadsPerRow <= 32);
+
+    const int row_idx = tid / kNThreadsPerRow;
+    const int col_idx = tid % kNThreadsPerRow;
+
+    float bias_val = params.bias_ptr == nullptr || chunk_c_id * kChunkSizeC + row_idx >= params.dim ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[chunk_c_id * kChunkSizeC + row_idx]);
+    float weight_vals[kWidth] = {0};
+    if (chunk_c_id + kChunkSizeC + row_idx < params.dim) {
+        #pragma unroll
+        for (int w = 0; w < kWidth; ++w) {
+            weight_vals[w] = weight[row_idx * params.weight_c_stride + w * params.weight_width_stride];
+        }
+    }
+    float x_vals[kWidth - 1 + kLPerThread];
+    #pragma unroll
+    for (int i = 0; i < kWidth - 1 + kLPerThread; ++i) {
+        x_vals[i] = float(x_smem[col_idx * kLPerThread + i][row_idx]);
+    }
+
+    float out_vals[kLPerThread];
+    #pragma unroll
+    for (int i = 0; i < kLPerThread; ++i) {
+        out_vals[i] = bias_val;
+        #pragma unroll
+        for (int w = 0; w < kWidth; ++w) { out_vals[i] += weight_vals[w] * x_vals[i + w]; }
+        if (params.silu_activation) {out_vals[i] = out_vals[i] / (1 + expf(-out_vals[i])); }
+    }
+
+    // Since kNThreadsPerRow is a power of 2 and <= 32, we only need syncwarp and not syncthreads.
+    __syncwarp();
+    #pragma unroll
+    for (int i = 0; i < kLPerThread; ++i) { x_smem[col_idx * kLPerThread + i][row_idx] = out_vals[i]; }
+    __syncthreads();
+
+    #pragma unroll
+    for (int l = 0; l < Ktraits::kNLoads; ++l) {
+        input_t out_vals_store[kNElts];
+        reinterpret_cast<vec_t *>(out_vals_store)[0] = reinterpret_cast<vec_t *>(x_smem[l * kLPerLoad + l_idx])[c_idx];
+        if (chunk_l_id * kChunkSizeL + l * kLPerLoad + l_idx < params.seqlen
+            && chunk_c_id * kChunkSizeC + c_idx * kNElts < params.dim) {
+            *reinterpret_cast<vec_t *>(out + l * kLPerLoad * params.out_l_stride) = reinterpret_cast<vec_t *>(out_vals_store)[0];
+        }
+    }
+
+}
+
+template<int kNThreads, int kWidth, typename input_t, typename weight_t>
+void causal_conv1d_channellast_fwd_launch(ConvParamsBase &params, cudaStream_t stream) {
+    using Ktraits = Causal_conv1d_channellast_fwd_kernel_traits<kNThreads, kWidth, 64, true, input_t, weight_t>;
+    // constexpr int kSmemSize = Ktraits::kSmemSize;
+    constexpr int kChunkSizeL = Ktraits::kChunkSizeL;
+    constexpr int kChunkSizeC = Ktraits::kNEltsPerRow;
+    const int n_chunks_L = (params.seqlen + kChunkSizeL - 1) / kChunkSizeL;
+    const int n_chunks_C = (params.dim + kChunkSizeC - 1) / kChunkSizeC;
+    // printf("n_chunks_L: %d, n_chunks_C: %d\n", n_chunks_L, n_chunks_C);
+    dim3 grid(params.batch, n_chunks_L, n_chunks_C);
+    dim3 block(Ktraits::kNThreads);
+    auto kernel = &causal_conv1d_channellast_fwd_kernel<Ktraits>;
+    // if (kSmemSize >= 48 * 1024) {
+    //     C10_CUDA_CHECK(cudaFuncSetAttribute(
+    //         kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
+    //     }
+    // kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
+    kernel<<<grid, Ktraits::kNThreads, 0, stream>>>(params);
+    C10_CUDA_KERNEL_LAUNCH_CHECK();
+}
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_channellast_fwd_cuda(ConvParamsBase &params, cudaStream_t stream) {
+    if (params.width == 2) {
+        causal_conv1d_channellast_fwd_launch<128, 2, input_t, weight_t>(params, stream);
+    } else if (params.width == 3) {
+        causal_conv1d_channellast_fwd_launch<128, 3, input_t, weight_t>(params, stream);
+    } else if (params.width == 4) {
+        causal_conv1d_channellast_fwd_launch<128, 4, input_t, weight_t>(params, stream);
+    }
+}
+
+template void causal_conv1d_fwd_cuda<float, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<at::Half, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<at::BFloat16, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<float, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<at::Half, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<at::BFloat16, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<float, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<at::Half, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_fwd_cuda<at::BFloat16, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+
+template void causal_conv1d_channellast_fwd_cuda<float, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<at::Half, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<at::BFloat16, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<float, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<at::Half, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<at::BFloat16, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<float, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<at::Half, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_channellast_fwd_cuda<at::BFloat16, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);

causal-conv1d/csrc/causal_conv1d_update.cu

@@ -0,0 +1,96 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#include <c10/util/BFloat16.h>
+#include <c10/util/Half.h>
+#include <c10/cuda/CUDAException.h>  // For C10_CUDA_CHECK and C10_CUDA_KERNEL_LAUNCH_CHECK
+
+#include <cub/block/block_load.cuh>
+#include <cub/block/block_store.cuh>
+
+#include "causal_conv1d.h"
+#include "causal_conv1d_common.h"
+#include "static_switch.h"
+
+template<int kNThreads_, int kWidth_, typename input_t_, typename weight_t_>
+struct Causal_conv1d_update_kernel_traits {
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr int kNThreads = kNThreads_;
+    static constexpr int kWidth = kWidth_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads)
+void causal_conv1d_update_kernel(ConvParamsBase params) {
+    constexpr int kWidth = Ktraits::kWidth;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    using input_t = typename Ktraits::input_t;
+    using weight_t = typename Ktraits::weight_t;
+
+    const int tidx = threadIdx.x;
+    const int batch_id = blockIdx.x;
+    const int channel_id = blockIdx.y * kNThreads + tidx;
+    input_t *x = reinterpret_cast<input_t *>(params.x_ptr) + batch_id * params.x_batch_stride
+        + channel_id * params.x_c_stride;
+    input_t *conv_state = reinterpret_cast<input_t *>(params.conv_state_ptr) + batch_id * params.conv_state_batch_stride
+        + channel_id * params.conv_state_c_stride;
+    weight_t *weight = reinterpret_cast<weight_t *>(params.weight_ptr) + channel_id * params.weight_c_stride;
+    input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
+        + channel_id * params.out_c_stride;
+    float bias_val = params.bias_ptr == nullptr || channel_id >= params.dim ? 0.f : float(reinterpret_cast<weight_t *>(params.bias_ptr)[channel_id]);
+
+    float weight_vals[kWidth] = {0};
+    if (channel_id < params.dim) {
+        #pragma unroll
+        for (int i = 0; i < kWidth; ++i) { weight_vals[i] = float(weight[i * params.weight_width_stride]); }
+    }
+
+    float x_vals[kWidth] = {0};
+    if (channel_id < params.dim) {
+        #pragma unroll
+        for (int i = 0; i < kWidth - 1; ++i) { x_vals[i] = float(conv_state[(i + 1) * params.conv_state_l_stride]); }
+        x_vals[kWidth - 1] = float(x[0]);
+        #pragma unroll
+        for (int i = 0; i < kWidth; ++i) { conv_state[i * params.conv_state_l_stride] = input_t(x_vals[i]); }
+    }
+
+    float out_val = bias_val;
+    #pragma unroll
+    for (int i = 0; i < kWidth; ++i) { out_val += weight_vals[i] * x_vals[i]; }
+    if (params.silu_activation) { out_val = out_val / (1 + expf(-out_val)); }
+    if (channel_id < params.dim) { out[0] = input_t(out_val); }
+}
+
+template<int kNThreads, int kWidth, typename input_t, typename weight_t>
+void causal_conv1d_update_launch(ConvParamsBase &params, cudaStream_t stream) {
+    using Ktraits = Causal_conv1d_update_kernel_traits<kNThreads, kWidth, input_t, weight_t>;
+    dim3 grid(params.batch, (params.dim + kNThreads - 1) / kNThreads);
+    auto kernel = &causal_conv1d_update_kernel<Ktraits>;
+    kernel<<<grid, Ktraits::kNThreads, 0, stream>>>(params);
+    C10_CUDA_KERNEL_LAUNCH_CHECK();
+}
+
+template<typename input_t, typename weight_t>
+void causal_conv1d_update_cuda(ConvParamsBase &params, cudaStream_t stream) {
+    if (params.width == 2) {
+        causal_conv1d_update_launch<64, 2, input_t, weight_t>(params, stream);
+    } else if (params.width == 3) {
+        causal_conv1d_update_launch<64, 3, input_t, weight_t>(params, stream);
+    } else if (params.width == 4) {
+        causal_conv1d_update_launch<64, 4, input_t, weight_t>(params, stream);
+    }
+}
+
+template void causal_conv1d_update_cuda<float, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<at::Half, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<at::BFloat16, float>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<float, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<at::Half, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<at::BFloat16, at::Half>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<float, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<at::Half, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);
+template void causal_conv1d_update_cuda<at::BFloat16, at::BFloat16>(ConvParamsBase &params, cudaStream_t stream);

causal-conv1d/csrc/static_switch.h

@@ -0,0 +1,25 @@
+// Inspired by https://github.com/NVIDIA/DALI/blob/main/include/dali/core/static_switch.h
+// and https://github.com/pytorch/pytorch/blob/master/aten/src/ATen/Dispatch.h
+
+#pragma once
+
+/// @param COND       - a boolean expression to switch by
+/// @param CONST_NAME - a name given for the constexpr bool variable.
+/// @param ...       - code to execute for true and false
+///
+/// Usage:
+/// ```
+/// BOOL_SWITCH(flag, BoolConst, [&] {
+///     some_function<BoolConst>(...);
+/// });
+/// ```
+#define BOOL_SWITCH(COND, CONST_NAME, ...)                                           \
+    [&] {                                                                            \
+        if (COND) {                                                                  \
+            static constexpr bool CONST_NAME = true;                                 \
+            return __VA_ARGS__();                                                    \
+        } else {                                                                     \
+            static constexpr bool CONST_NAME = false;                                \
+            return __VA_ARGS__();                                                    \
+        }                                                                            \
+    }()

causal-conv1d/setup.py

@@ -0,0 +1,264 @@
+# Copyright (c) 2023, Tri Dao.
+import sys
+import warnings
+import os
+import re
+import ast
+from pathlib import Path
+from packaging.version import parse, Version
+import platform
+
+from setuptools import setup, find_packages
+import subprocess
+
+import urllib.request
+import urllib.error
+from wheel.bdist_wheel import bdist_wheel as _bdist_wheel
+
+import torch
+from torch.utils.cpp_extension import (
+    BuildExtension,
+    CppExtension,
+    CUDAExtension,
+    CUDA_HOME,
+)
+
+
+with open("README.md", "r", encoding="utf-8") as fh:
+    long_description = fh.read()
+
+
+# ninja build does not work unless include_dirs are abs path
+this_dir = os.path.dirname(os.path.abspath(__file__))
+
+PACKAGE_NAME = "causal_conv1d"
+
+BASE_WHEEL_URL = "https://github.com/Dao-AILab/causal-conv1d/releases/download/{tag_name}/{wheel_name}"
+
+# FORCE_BUILD: Force a fresh build locally, instead of attempting to find prebuilt wheels
+# SKIP_CUDA_BUILD: Intended to allow CI to use a simple `python setup.py sdist` run to copy over raw files, without any cuda compilation
+FORCE_BUILD = os.getenv("CAUSAL_CONV1D_FORCE_BUILD", "FALSE") == "TRUE"
+SKIP_CUDA_BUILD = os.getenv("CAUSAL_CONV1D_SKIP_CUDA_BUILD", "FALSE") == "TRUE"
+# For CI, we want the option to build with C++11 ABI since the nvcr images use C++11 ABI
+FORCE_CXX11_ABI = os.getenv("CAUSAL_CONV1D_FORCE_CXX11_ABI", "FALSE") == "TRUE"
+
+
+def get_platform():
+    """
+    Returns the platform name as used in wheel filenames.
+    """
+    if sys.platform.startswith("linux"):
+        return "linux_x86_64"
+    elif sys.platform == "darwin":
+        mac_version = ".".join(platform.mac_ver()[0].split(".")[:2])
+        return f"macosx_{mac_version}_x86_64"
+    elif sys.platform == "win32":
+        return "win_amd64"
+    else:
+        raise ValueError("Unsupported platform: {}".format(sys.platform))
+
+
+def get_cuda_bare_metal_version(cuda_dir):
+    raw_output = subprocess.check_output(
+        [cuda_dir + "/bin/nvcc", "-V"], universal_newlines=True
+    )
+    output = raw_output.split()
+    release_idx = output.index("release") + 1
+    bare_metal_version = parse(output[release_idx].split(",")[0])
+
+    return raw_output, bare_metal_version
+
+
+def check_if_cuda_home_none(global_option: str) -> None:
+    if CUDA_HOME is not None:
+        return
+    # warn instead of error because user could be downloading prebuilt wheels, so nvcc won't be necessary
+    # in that case.
+    warnings.warn(
+        f"{global_option} was requested, but nvcc was not found.  Are you sure your environment has nvcc available?  "
+        "If you're installing within a container from https://hub.docker.com/r/pytorch/pytorch, "
+        "only images whose names contain 'devel' will provide nvcc."
+    )
+
+
+def append_nvcc_threads(nvcc_extra_args):
+    return nvcc_extra_args + ["--threads", "4"]
+
+
+cmdclass = {}
+ext_modules = []
+
+if not SKIP_CUDA_BUILD:
+    print("\n\ntorch.__version__  = {}\n\n".format(torch.__version__))
+    TORCH_MAJOR = int(torch.__version__.split(".")[0])
+    TORCH_MINOR = int(torch.__version__.split(".")[1])
+
+    check_if_cuda_home_none("causal_conv1d")
+    # Check, if CUDA11 is installed for compute capability 8.0
+    cc_flag = []
+    if CUDA_HOME is not None:
+        _, bare_metal_version = get_cuda_bare_metal_version(CUDA_HOME)
+        if bare_metal_version < Version("11.6"):
+            raise RuntimeError(
+                "causal_conv1d is only supported on CUDA 11.6 and above.  "
+                "Note: make sure nvcc has a supported version by running nvcc -V."
+            )
+
+    cc_flag.append("-gencode")
+    cc_flag.append("arch=compute_70,code=sm_70")
+    cc_flag.append("-gencode")
+    cc_flag.append("arch=compute_80,code=sm_80")
+    if bare_metal_version >= Version("11.8"):
+        cc_flag.append("-gencode")
+        cc_flag.append("arch=compute_90,code=sm_90")
+
+    # HACK: The compiler flag -D_GLIBCXX_USE_CXX11_ABI is set to be the same as
+    # torch._C._GLIBCXX_USE_CXX11_ABI
+    # https://github.com/pytorch/pytorch/blob/8472c24e3b5b60150096486616d98b7bea01500b/torch/utils/cpp_extension.py#L920
+    if FORCE_CXX11_ABI:
+        torch._C._GLIBCXX_USE_CXX11_ABI = True
+
+    ext_modules.append(
+        CUDAExtension(
+            name="causal_conv1d_cuda",
+            sources=[
+                "csrc/causal_conv1d.cpp",
+                "csrc/causal_conv1d_fwd.cu",
+                "csrc/causal_conv1d_bwd.cu",
+                "csrc/causal_conv1d_update.cu",
+            ],
+            extra_compile_args={
+                "cxx": ["-O3"],
+                "nvcc": append_nvcc_threads(
+                    [
+                        "-O3",
+                        "-U__CUDA_NO_HALF_OPERATORS__",
+                        "-U__CUDA_NO_HALF_CONVERSIONS__",
+                        "-U__CUDA_NO_BFLOAT16_OPERATORS__",
+                        "-U__CUDA_NO_BFLOAT16_CONVERSIONS__",
+                        "-U__CUDA_NO_BFLOAT162_OPERATORS__",
+                        "-U__CUDA_NO_BFLOAT162_CONVERSIONS__",
+                        "--expt-relaxed-constexpr",
+                        "--expt-extended-lambda",
+                        "--use_fast_math",
+                        "--ptxas-options=-v",
+                        "-lineinfo",
+                    ]
+                    + cc_flag
+                ),
+            },
+            include_dirs=[this_dir],
+        )
+    )
+
+
+def get_package_version():
+    with open(Path(this_dir) / "causal_conv1d" / "__init__.py", "r") as f:
+        version_match = re.search(r"^__version__\s*=\s*(.*)$", f.read(), re.MULTILINE)
+    public_version = ast.literal_eval(version_match.group(1))
+    local_version = os.environ.get("CAUSAL_CONV1D_LOCAL_VERSION")
+    if local_version:
+        return f"{public_version}+{local_version}"
+    else:
+        return str(public_version)
+
+
+def get_wheel_url():
+    # Determine the version numbers that will be used to determine the correct wheel
+    # We're using the CUDA version used to build torch, not the one currently installed
+    # _, cuda_version_raw = get_cuda_bare_metal_version(CUDA_HOME)
+    torch_cuda_version = parse(torch.version.cuda)
+    torch_version_raw = parse(torch.__version__)
+    # For CUDA 11, we only compile for CUDA 11.8, and for CUDA 12 we only compile for CUDA 12.2
+    # to save CI time. Minor versions should be compatible.
+    torch_cuda_version = parse("11.8") if torch_cuda_version.major == 11 else parse("12.2")
+    python_version = f"cp{sys.version_info.major}{sys.version_info.minor}"
+    platform_name = get_platform()
+    causal_conv1d_version = get_package_version()
+    # cuda_version = f"{cuda_version_raw.major}{cuda_version_raw.minor}"
+    cuda_version = f"{torch_cuda_version.major}{torch_cuda_version.minor}"
+    torch_version = f"{torch_version_raw.major}.{torch_version_raw.minor}"
+    cxx11_abi = str(torch._C._GLIBCXX_USE_CXX11_ABI).upper()
+
+    # Determine wheel URL based on CUDA version, torch version, python version and OS
+    wheel_filename = f"{PACKAGE_NAME}-{causal_conv1d_version}+cu{cuda_version}torch{torch_version}cxx11abi{cxx11_abi}-{python_version}-{python_version}-{platform_name}.whl"
+    wheel_url = BASE_WHEEL_URL.format(
+        tag_name=f"v{causal_conv1d_version}", wheel_name=wheel_filename
+    )
+    return wheel_url, wheel_filename
+
+
+class CachedWheelsCommand(_bdist_wheel):
+    """
+    The CachedWheelsCommand plugs into the default bdist wheel, which is ran by pip when it cannot
+    find an existing wheel (which is currently the case for all installs). We use
+    the environment parameters to detect whether there is already a pre-built version of a compatible
+    wheel available and short-circuits the standard full build pipeline.
+    """
+
+    def run(self):
+        if FORCE_BUILD:
+            return super().run()
+
+        wheel_url, wheel_filename = get_wheel_url()
+        print("Guessing wheel URL: ", wheel_url)
+        try:
+            urllib.request.urlretrieve(wheel_url, wheel_filename)
+
+            # Make the archive
+            # Lifted from the root wheel processing command
+            # https://github.com/pypa/wheel/blob/cf71108ff9f6ffc36978069acb28824b44ae028e/src/wheel/bdist_wheel.py#LL381C9-L381C85
+            if not os.path.exists(self.dist_dir):
+                os.makedirs(self.dist_dir)
+
+            impl_tag, abi_tag, plat_tag = self.get_tag()
+            archive_basename = f"{self.wheel_dist_name}-{impl_tag}-{abi_tag}-{plat_tag}"
+
+            wheel_path = os.path.join(self.dist_dir, archive_basename + ".whl")
+            print("Raw wheel path", wheel_path)
+            os.rename(wheel_filename, wheel_path)
+        except urllib.error.HTTPError:
+            print("Precompiled wheel not found. Building from source...")
+            # If the wheel could not be downloaded, build from source
+            super().run()
+
+
+setup(
+    name=PACKAGE_NAME,
+    version=get_package_version(),
+    packages=find_packages(
+        exclude=(
+            "build",
+            "csrc",
+            "include",
+            "tests",
+            "dist",
+            "docs",
+            "benchmarks",
+            "causal_conv1d.egg-info",
+        )
+    ),
+    author="Tri Dao",
+    author_email="tri@tridao.me",
+    description="Causal depthwise conv1d in CUDA, with a PyTorch interface",
+    long_description=long_description,
+    long_description_content_type="text/markdown",
+    url="https://github.com/Dao-AILab/causal-conv1d",
+    classifiers=[
+        "Programming Language :: Python :: 3",
+        "License :: OSI Approved :: BSD License",
+        "Operating System :: Unix",
+    ],
+    ext_modules=ext_modules,
+    cmdclass={"bdist_wheel": CachedWheelsCommand, "build_ext": BuildExtension}
+    if ext_modules
+    else {
+        "bdist_wheel": CachedWheelsCommand,
+    },
+    python_requires=">=3.7",
+    install_requires=[
+        "torch",
+        "packaging",
+        "ninja",
+    ],
+)

causal-conv1d/tests/test_causal_conv1d.py

@@ -0,0 +1,173 @@
+# Copyright (C) 2023, Tri Dao.
+
+import math
+
+import torch
+import pytest
+
+from einops import rearrange
+
+from causal_conv1d.causal_conv1d_interface import causal_conv1d_fn, causal_conv1d_ref
+from causal_conv1d.causal_conv1d_interface import causal_conv1d_update, causal_conv1d_update_ref
+
+
+@pytest.mark.parametrize("channel_last", [False, True])
+# @pytest.mark.parametrize('channel_last', [True])
+@pytest.mark.parametrize("itype", [torch.float32, torch.float16, torch.bfloat16])
+# @pytest.mark.parametrize('itype', [torch.float16])
+@pytest.mark.parametrize("silu_activation", [False, True])
+# @pytest.mark.parametrize('silu_activation', [True])
+@pytest.mark.parametrize("has_bias", [False, True])
+# @pytest.mark.parametrize('has_bias', [True])
+@pytest.mark.parametrize("width", [2, 3, 4])
+# @pytest.mark.parametrize('width', [2])
+@pytest.mark.parametrize(
+    "seqlen", [8, 16, 32, 64, 128, 151, 256, 372, 512, 784, 1024, 1134, 2048, 4096]
+)
+# @pytest.mark.parametrize('seqlen', [8, 16, 32, 64, 128, 256, 512, 784, 1024, 2048, 4096])
+# @pytest.mark.parametrize('seqlen', [128])
+def test_causal_conv1d(seqlen, width, has_bias, silu_activation, itype, channel_last):
+    device = "cuda"
+    rtol, atol = (3e-4, 1e-3) if itype == torch.float32 else (3e-3, 5e-3)
+    if itype == torch.bfloat16:
+        rtol, atol = 1e-2, 5e-2
+    rtolw, atolw = (1e-3, 1e-3)
+    # set seed
+    torch.random.manual_seed(0)
+    batch_size = 2
+    # batch_size = 1
+    dim = 4096 + 32  # Try dim not divisible by 64
+    # dim = 64
+    if not channel_last:
+        x = torch.randn(batch_size, 4096 + dim + 64, seqlen, device=device, dtype=itype)[:, 4096:4096 + dim, :].requires_grad_()
+    else:
+        x = rearrange(
+            torch.randn(batch_size, seqlen, 4096 + dim + 64, device=device, dtype=itype)[:, :, 4096:4096 + dim], "b s d -> b d s"
+        ).requires_grad_()
+    weight = torch.randn(dim, width, device=device, dtype=torch.float32, requires_grad=True)
+    if has_bias:
+        bias = torch.randn(dim, device=device, dtype=torch.float32, requires_grad=True)
+    else:
+        bias = None
+    x_ref = x.detach().clone().requires_grad_()
+    weight_ref = weight.detach().clone().requires_grad_()
+    bias_ref = bias.detach().clone().requires_grad_() if bias is not None else None
+    activation = None if not silu_activation else "silu"
+    out = causal_conv1d_fn(x, weight, bias, activation=activation)
+    out_ref = causal_conv1d_ref(x_ref, weight_ref, bias_ref, activation=activation)
+
+    print(f"Output max diff: {(out - out_ref).abs().max().item()}")
+    print(f"Output mean diff: {(out - out_ref).abs().mean().item()}")
+    assert torch.allclose(out, out_ref, rtol=rtol, atol=atol)
+
+    g = torch.randn_like(out)
+    out_ref.backward(g)
+    out.backward(g)
+
+    print(f"dx max diff: {(x.grad - x_ref.grad).abs().max().item()}")
+    print(f"dweight max diff: {(weight.grad - weight_ref.grad).abs().max().item()}")
+    if has_bias:
+        print(f"dbias max diff: {(bias.grad - bias_ref.grad).abs().max().item()}")
+
+    assert torch.allclose(x.grad, x_ref.grad.to(dtype=itype), rtol=rtol, atol=atol)
+    assert torch.allclose(weight.grad, weight_ref.grad, rtol=rtolw, atol=atolw)
+    if has_bias:
+        assert torch.allclose(bias.grad, bias_ref.grad, rtol=rtolw, atol=atolw)
+
+
+@pytest.mark.parametrize("itype", [torch.float32, torch.float16, torch.bfloat16])
+# @pytest.mark.parametrize('itype', [torch.float16])
+@pytest.mark.parametrize("silu_activation", [False, True])
+# @pytest.mark.parametrize('silu_activation', [False])
+@pytest.mark.parametrize("has_bias", [False, True])
+# @pytest.mark.parametrize('has_bias', [True])
+@pytest.mark.parametrize("width", [2, 3, 4])
+# @pytest.mark.parametrize('width', [2])
+@pytest.mark.parametrize("dim", [2048, 2048 + 16, 4096])
+# @pytest.mark.parametrize("dim", [2048])
+def test_causal_conv1d_update(dim, width, has_bias, silu_activation, itype):
+    device = "cuda"
+    rtol, atol = (3e-4, 1e-3) if itype == torch.float32 else (3e-3, 5e-3)
+    if itype == torch.bfloat16:
+        rtol, atol = 1e-2, 5e-2
+    rtolw, atolw = (1e-3, 1e-3)
+    # set seed
+    torch.random.manual_seed(0)
+    batch_size = 2
+    # batch_size = 1
+    # dim = 64
+    x = torch.randn(batch_size, dim, device=device, dtype=itype)
+    conv_state = torch.randn(batch_size, dim, width, device=device, dtype=itype)
+    weight = torch.randn(dim, width, device=device, dtype=torch.float32, requires_grad=True)
+    if has_bias:
+        bias = torch.randn(dim, device=device, dtype=torch.float32, requires_grad=True)
+    else:
+        bias = None
+    conv_state_ref = conv_state.detach().clone()
+    activation = None if not silu_activation else "silu"
+    out = causal_conv1d_update(x, conv_state, weight, bias, activation=activation)
+    out_ref = causal_conv1d_update_ref(x, conv_state_ref, weight, bias, activation=activation)
+
+    print(f"Output max diff: {(out - out_ref).abs().max().item()}")
+    print(f"Output mean diff: {(out - out_ref).abs().mean().item()}")
+    assert torch.equal(conv_state, conv_state_ref)
+    assert torch.allclose(out, out_ref, rtol=rtol, atol=atol)
+
+
+# @pytest.mark.parametrize("channel_last", [False, True])
+@pytest.mark.parametrize('channel_last', [True])
+# @pytest.mark.parametrize("itype", [torch.float32, torch.float16, torch.bfloat16])
+@pytest.mark.parametrize('itype', [torch.bfloat16])
+# @pytest.mark.parametrize("silu_activation", [False, True])
+@pytest.mark.parametrize('silu_activation', [True])
+# @pytest.mark.parametrize("has_bias", [False, True])
+@pytest.mark.parametrize('has_bias', [True])
+# @pytest.mark.parametrize("width", [2, 3, 4])
+@pytest.mark.parametrize('width', [4])
+@pytest.mark.parametrize(
+    # "seqlen", [8, 16, 32, 64, 128, 151, 256, 372, 512, 784, 1024, 1134, 2048, 4096]
+    "seqlen", [2048]
+)
+# @pytest.mark.parametrize('seqlen', [8, 16, 32, 64, 128, 256, 512, 784, 1024, 2048, 4096])
+# @pytest.mark.parametrize('seqlen', [128])
+def test_causal_conv1d_race_condition(seqlen, width, has_bias, silu_activation, itype, channel_last):
+    device = "cuda"
+    # set seed
+    torch.random.manual_seed(0)
+    batch_size = 2
+    # batch_size = 1
+    dim = 4096 + 32  # Try dim not divisible by 64
+    # dim = 64
+    if not channel_last:
+        x = torch.randn(batch_size, 4096 + dim + 64, seqlen, device=device, dtype=itype)[:, 4096:4096 + dim, :].requires_grad_()
+    else:
+        x = rearrange(
+            torch.randn(batch_size, seqlen, 4096 + dim + 64, device=device, dtype=itype)[:, :, 4096:4096 + dim], "b s d -> b d s"
+        ).requires_grad_()
+    weight = torch.randn(dim, width, device=device, dtype=torch.float32, requires_grad=True)
+    if has_bias:
+        bias = torch.randn(dim, device=device, dtype=torch.float32, requires_grad=True)
+    else:
+        bias = None
+    activation = None if not silu_activation else "silu"
+    out0 = causal_conv1d_fn(x, weight, bias, activation=activation)
+    g = torch.randn_like(out0)
+    dx0, dw0, db0 = torch.autograd.grad(out0, (x, weight, bias), g)
+    dw_atol = 1e-4
+    db_atol = 1e-4
+
+    for i in range(10000):
+        out = causal_conv1d_fn(x, weight, bias, activation=activation)
+        dx, dw, db = torch.autograd.grad(out, (x, weight, bias), g)
+        dw_equal = torch.allclose(dw, dw0, atol=dw_atol)
+        # if not dw_equal:
+        #     breakpoint()
+        if has_bias:
+            db_equal = torch.allclose(db, db0, atol=db_atol)
+            # if not db_equal:
+            #     breakpoint()
+        assert torch.equal(out, out0)
+        assert torch.equal(dx, dx0)
+        assert dw_equal
+        if has_bias:
+            assert dw_equal

causal_conv1d-1.0.0-cp310-cp310-linux_x86_64.whl

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:7b333b18799ea71506f702085587656a527ac835aca8610073a76fe1f60fe576
-size 9050678

install.sh

@@ -0,0 +1,2 @@
+pip install -e causal-conv1d
+pip install -e mamba

mamba/.gitmodules

@@ -0,0 +1,3 @@
+[submodule "3rdparty/lm-evaluation-harness"]
+	path = 3rdparty/lm-evaluation-harness
+	url = https://github.com/EleutherAI/lm-evaluation-harness/

mamba/AUTHORS

@@ -0,0 +1,2 @@
+Tri Dao, tri@tridao.me
+Albert Gu, agu@andrew.cmu.edu

mamba/LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
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+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
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+      "Contribution" shall mean any work of authorship, including
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+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
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+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+   3. Grant of Patent License. Subject to the terms and conditions of
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+
+   4. Redistribution. You may reproduce and distribute copies of the
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+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
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+
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+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
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+          that such additional attribution notices cannot be construed
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+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright 2023 Tri Dao, Albert Gu
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

mamba/README.md

@@ -0,0 +1,149 @@
+# Mamba
+
+![Mamba](assets/selection.png "Selective State Space")
+> **Mamba: Linear-Time Sequence Modeling with Selective State Spaces**\
+> Albert Gu*, Tri Dao*\
+> Paper: https://arxiv.org/abs/2312.00752
+
+## About
+
+Mamba is a new state space model architecture showing promising performance on information-dense data such as language modeling, where previous subquadratic models fall short of Transformers.
+It is based on the line of progress on [structured state space models](https://github.com/state-spaces/s4),
+with an efficient hardware-aware design and implementation in the spirit of [FlashAttention](https://github.com/Dao-AILab/flash-attention).
+
+## Installation
+
+- `pip install causal-conv1d`: an efficient implementation of a simple causal Conv1d layer used inside the Mamba block.
+- `pip install mamba-ssm`: the core Mamba package.
+
+It can also be built from source with `pip install .` from this repository.
+
+If `pip` complains about PyTorch versions, try passing `--no-build-isolation` to `pip`.
+
+Other requirements:
+- Linux
+- NVIDIA GPU
+- PyTorch 1.12+
+- CUDA 11.6+
+
+## Usage
+
+We expose several levels of interface with the Mamba model.
+
+### Selective SSM
+
+Mamba is based on a selective SSM layer, which is the focus of the paper (Section 3; Algorithm 2).
+
+Source: [ops/selective_scan_interface.py](mamba_ssm/ops/selective_scan_interface.py).
+
+### Mamba Block
+
+The main module of this repository is the Mamba architecture block wrapping the selective SSM.
+
+Source: [modules/mamba_simple.py](mamba_ssm/modules/mamba_simple.py).
+
+Usage:
+```
+from mamba_ssm import Mamba
+
+batch, length, dim = 2, 64, 16
+x = torch.randn(batch, length, dim).to("cuda")
+model = Mamba(
+    # This module uses roughly 3 * expand * d_model^2 parameters
+    d_model=dim, # Model dimension d_model
+    d_state=16,  # SSM state expansion factor
+    d_conv=4,    # Local convolution width
+    expand=2,    # Block expansion factor
+).to("cuda")
+y = model(x)
+assert y.shape == x.shape
+```
+
+### Mamba Language Model
+
+Finally, we provide an example of a complete language model: a deep sequence model backbone (with repeating Mamba blocks) + language model head.
+
+Source: [models/mixer_seq_simple.py](mamba_ssm/models/mixer_seq_simple.py).
+
+This is an example of how to integrate Mamba into an end-to-end neural network.
+This example is used in the generation scripts below.
+
+
+
+## Pretrained Models
+
+Pretrained models are uploaded to
+[HuggingFace](https://huggingface.co/state-spaces): `mamba-130m`, `mamba-370m`,
+`mamba-790m`, `mamba-1.4b`, `mamba-2.8b`.
+
+The models will be autodownloaded by the generation script below.
+
+These models were trained on the [Pile](https://huggingface.co/datasets/EleutherAI/pile), and follow the standard model dimensions described by GPT-3 and followed by many open source models:
+
+| Parameters | Layers | Model dim. | 
+|------------|--------|------------|
+| 130M       | 12     | 768        |
+| 370M       | 24     | 1024       |
+| 790M       | 24     | 1536       |
+| 1.4B       | 24     | 2048       |
+| 2.8B       | 32     | 2560       |
+
+(The layer count of Mamba should be doubled, as two Mamba blocks are needed for each "layer" (MHA block + MLP block) of a Transformer.)
+
+Note: these are base models trained only for 300B tokens, without any form of downstream modification (instruction tuning, etc.).
+Performance is expected to be comparable or better than other architectures trained on similar data, but not to match larger or fine-tuned models.
+
+
+## Evaluations
+
+To run zero-shot evaluations of models (corresponding to Table 3 of the paper),
+we use the
+[lm-evaluation-harness](https://github.com/EleutherAI/lm-evaluation-harness/tree/big-refactor)
+library.
+
+1. Pull the `lm-evaluation-harness` repo by `git submodule update --init
+   --recursive`. We use the `big-refactor` branch.
+2. Install `lm-evaluation-harness`: `pip install -e 3rdparty/lm-evaluation-harness`
+3. Run evaluation with (more documentation at the [lm-evaluation-harness](https://github.com/EleutherAI/lm-evaluation-harness/tree/big-refactor) repo):
+```
+python evals/lm_harness_eval.py --model mamba --model_args pretrained=state-spaces/mamba-130m --tasks lambada_openai,hellaswag,piqa,arc_easy,arc_challenge,winogrande --device cuda --batch_size 64
+python evals/lm_harness_eval.py --model hf --model_args pretrained=EleutherAI/pythia-160m --tasks lambada_openai,hellaswag,piqa,arc_easy,arc_challenge,winogrande --device cuda --batch_size 64
+```
+
+Note that the result of each task might differ from reported values by 0.1-0.3 due to noise in the evaluation process.
+
+## Inference
+
+The script [benchmarks/benchmark_generation_mamba_simple.py](benchmarks/benchmark_generation_mamba_simple.py)
+1. autoloads a model from the HuggingFace Hub,
+2. generates completions of a user-specified prompt,
+3. benchmarks the inference speed of this generation.
+
+Other configurable options include the top-p (nucleus sampling) probability, and the softmax temperature.
+
+### Examples
+
+To test generation latency (e.g. batch size = 1) with different sampling strategies:
+
+```
+python benchmarks/benchmark_generation_mamba_simple.py --model-name "state-spaces/mamba-2.8b" --prompt "My cat wrote all this CUDA code for a new language model and" --topp 0.9 --temperature 0.5
+python benchmarks/benchmark_generation_mamba_simple.py --model-name "EleutherAI/pythia-2.8b" --prompt "My cat wrote all this CUDA code for a new language model and" --topp 0.9 --temperature 0.5
+```
+
+To test generation throughput with random prompts (e.g. large batch size):
+```
+python benchmarks/benchmark_generation_mamba_simple.py --model-name "state-spaces/mamba-2.8b" --batch 128
+python benchmarks/benchmark_generation_mamba_simple.py --model-name "EleutherAI/pythia-2.8b" --batch 128
+```
+
+## Citation
+
+If you use this codebase, or otherwise found our work valuable, please cite Mamba:
+```
+@article{mamba,
+  title={Mamba: Linear-Time Sequence Modeling with Selective State Spaces},
+  author={Gu, Albert and Dao, Tri},
+  journal={arXiv preprint arXiv:2312.00752},
+  year={2023}
+}
+```

mamba/benchmarks/benchmark_generation_mamba_simple.py

@@ -0,0 +1,88 @@
+# Copyright (c) 2023, Tri Dao, Albert Gu.
+
+import argparse
+import time
+import json
+
+import torch
+import torch.nn.functional as F
+
+from einops import rearrange
+
+from transformers import AutoTokenizer, AutoModelForCausalLM
+
+from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel
+
+
+parser = argparse.ArgumentParser(description="Generation benchmarking")
+parser.add_argument("--model-name", type=str, default="state-spaces/mamba-130m")
+parser.add_argument("--prompt", type=str, default=None)
+parser.add_argument("--promptlen", type=int, default=100)
+parser.add_argument("--genlen", type=int, default=100)
+parser.add_argument("--temperature", type=float, default=1.0)
+parser.add_argument("--topk", type=int, default=1)
+parser.add_argument("--topp", type=float, default=1.0)
+parser.add_argument("--batch", type=int, default=1)
+args = parser.parse_args()
+
+repeats = 3
+device = "cuda"
+dtype = torch.float16
+
+print(f"Loading model {args.model_name}")
+is_mamba = args.model_name.startswith("state-spaces/mamba-") or "mamba" in args.model_name
+
+if is_mamba:
+    tokenizer = AutoTokenizer.from_pretrained("/home/zhulianghui/VisionProjects/mamba/ckpts/gpt-neox-20b-tokenizer")
+    model = MambaLMHeadModel.from_pretrained(args.model_name, device=device, dtype=dtype)
+else:
+    tokenizer = AutoTokenizer.from_pretrained(args.model_name)
+    model = AutoModelForCausalLM.from_pretrained(args.model_name, device_map={"": device}, torch_dtype=dtype)
+model.eval()
+print(f"Number of parameters: {sum(p.numel() for p in model.parameters() if p.requires_grad)}")
+
+torch.random.manual_seed(0)
+if args.prompt is None:
+    input_ids = torch.randint(1, 1000, (args.batch, args.promptlen), dtype=torch.long, device="cuda")
+    attn_mask = torch.ones_like(input_ids, dtype=torch.long, device="cuda")
+else:
+    tokens = tokenizer(args.prompt, return_tensors="pt")
+    input_ids = tokens.input_ids.to(device=device)
+    attn_mask = tokens.attention_mask.to(device=device)
+max_length = input_ids.shape[1] + args.genlen
+
+if is_mamba:
+    fn = lambda: model.generate(
+        input_ids=input_ids,
+        max_length=max_length,
+        cg=True,
+        return_dict_in_generate=True,
+        output_scores=True,
+        enable_timing=False,
+        temperature=args.temperature,
+        top_k=args.topk,
+        top_p=args.topp,
+    )
+else:
+    fn = lambda: model.generate(
+        input_ids=input_ids,
+        attention_mask=attn_mask,
+        max_length=max_length,
+        return_dict_in_generate=True,
+        pad_token_id=tokenizer.eos_token_id,
+        do_sample=True,
+        temperature=args.temperature,
+        top_k=args.topk,
+        top_p=args.topp,
+    )
+out = fn()
+if args.prompt is not None:
+    print(tokenizer.batch_decode(out.sequences.tolist()))
+
+torch.cuda.synchronize()
+start = time.time()
+for _ in range(repeats):
+    fn()
+torch.cuda.synchronize()
+print(f"Prompt length: {len(input_ids[0])}, generation length: {len(out.sequences[0]) - len(input_ids[0])}")
+print(f"{args.model_name} prompt processing + decoding time: {(time.time() - start) / repeats * 1000:.0f}ms")

mamba/csrc/selective_scan/reverse_scan.cuh

@@ -0,0 +1,401 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+#include <cub/config.cuh>
+
+#include <cub/util_ptx.cuh>
+#include <cub/util_type.cuh>
+#include <cub/block/block_raking_layout.cuh>
+// #include <cub/detail/uninitialized_copy.cuh>
+#include "uninitialized_copy.cuh"
+
+/**
+ * Perform a reverse sequential reduction over \p LENGTH elements of the \p input array.  The aggregate is returned.
+ */
+template <
+    int         LENGTH,
+    typename    T,
+    typename    ReductionOp>
+__device__ __forceinline__ T ThreadReverseReduce(const T (&input)[LENGTH], ReductionOp reduction_op) {
+    static_assert(LENGTH > 0);
+    T retval = input[LENGTH - 1];
+    #pragma unroll
+    for (int i = LENGTH - 2; i >= 0; --i) { retval = reduction_op(retval, input[i]); }
+    return retval;
+}
+
+/**
+ * Perform a sequential inclusive postfix reverse scan over the statically-sized \p input array, seeded with the specified \p postfix.  The aggregate is returned.
+ */
+template <
+    int         LENGTH,
+    typename    T,
+    typename    ScanOp>
+__device__ __forceinline__ T ThreadReverseScanInclusive(
+    const T (&input)[LENGTH],
+    T (&output)[LENGTH],
+    ScanOp scan_op,
+    const T postfix)
+{
+    T inclusive = postfix;
+    #pragma unroll
+    for (int i = LENGTH - 1; i >= 0; --i) {
+        inclusive = scan_op(inclusive, input[i]);
+        output[i] = inclusive;
+    }
+}
+
+/**
+ * Perform a sequential exclusive postfix reverse scan over the statically-sized \p input array, seeded with the specified \p postfix.  The aggregate is returned.
+ */
+template <
+    int         LENGTH,
+    typename    T,
+    typename    ScanOp>
+__device__ __forceinline__ T ThreadReverseScanExclusive(
+    const T (&input)[LENGTH],
+    T (&output)[LENGTH],
+    ScanOp scan_op,
+    const T postfix)
+{
+    // Careful, output maybe be aliased to input
+    T exclusive = postfix;
+    T inclusive;
+    #pragma unroll
+    for (int i = LENGTH - 1; i >= 0; --i) {
+        inclusive = scan_op(exclusive, input[i]);
+        output[i] = exclusive;
+        exclusive = inclusive;
+    }
+    return inclusive;
+}
+
+
+/**
+ * \brief WarpReverseScan provides SHFL-based variants of parallel postfix scan of items partitioned across a CUDA thread warp.
+ *
+ * LOGICAL_WARP_THREADS must be a power-of-two
+ */
+template <
+    typename    T,                      ///< Data type being scanned
+    int         LOGICAL_WARP_THREADS    ///< Number of threads per logical warp
+    >
+struct WarpReverseScan {
+    //---------------------------------------------------------------------
+    // Constants and type definitions
+    //---------------------------------------------------------------------
+
+    /// Whether the logical warp size and the PTX warp size coincide
+    static constexpr bool IS_ARCH_WARP = (LOGICAL_WARP_THREADS == CUB_WARP_THREADS(0));
+    /// The number of warp scan steps
+    static constexpr int STEPS = cub::Log2<LOGICAL_WARP_THREADS>::VALUE;
+    static_assert(LOGICAL_WARP_THREADS == 1 << STEPS);
+
+
+    //---------------------------------------------------------------------
+    // Thread fields
+    //---------------------------------------------------------------------
+
+    /// Lane index in logical warp
+    unsigned int lane_id;
+
+    /// Logical warp index in 32-thread physical warp
+    unsigned int warp_id;
+
+    /// 32-thread physical warp member mask of logical warp
+    unsigned int member_mask;
+
+    //---------------------------------------------------------------------
+    // Construction
+    //---------------------------------------------------------------------
+
+    /// Constructor
+    explicit __device__ __forceinline__
+    WarpReverseScan()
+        : lane_id(cub::LaneId())
+        , warp_id(IS_ARCH_WARP ? 0 : (lane_id / LOGICAL_WARP_THREADS))
+        , member_mask(cub::WarpMask<LOGICAL_WARP_THREADS>(warp_id))
+    {
+        if (!IS_ARCH_WARP) {
+            lane_id = lane_id % LOGICAL_WARP_THREADS;
+        }
+    }
+
+
+    /// Broadcast
+    __device__ __forceinline__ T Broadcast(
+        T               input,              ///< [in] The value to broadcast
+        int             src_lane)           ///< [in] Which warp lane is to do the broadcasting
+    {
+        return cub::ShuffleIndex<LOGICAL_WARP_THREADS>(input, src_lane, member_mask);
+    }
+
+
+    /// Inclusive scan
+    template <typename ScanOpT>
+    __device__ __forceinline__ void InclusiveReverseScan(
+        T               input,              ///< [in] Calling thread's input item.
+        T               &inclusive_output,  ///< [out] Calling thread's output item.  May be aliased with \p input.
+        ScanOpT         scan_op)            ///< [in] Binary scan operator
+    {
+        inclusive_output = input;
+        #pragma unroll
+        for (int STEP = 0; STEP < STEPS; STEP++) {
+            int offset = 1 << STEP;
+            T temp = cub::ShuffleDown<LOGICAL_WARP_THREADS>(
+                inclusive_output, offset, LOGICAL_WARP_THREADS - 1, member_mask
+            );
+            // Perform scan op if from a valid peer
+            inclusive_output = static_cast<int>(lane_id) >= LOGICAL_WARP_THREADS - offset
+                ? inclusive_output : scan_op(temp, inclusive_output);
+        }
+    }
+
+    /// Exclusive scan
+    // Get exclusive from inclusive
+    template <typename ScanOpT>
+    __device__ __forceinline__ void ExclusiveReverseScan(
+        T              input,              ///< [in] Calling thread's input item.
+        T              &exclusive_output,  ///< [out] Calling thread's output item.  May be aliased with \p input.
+        ScanOpT        scan_op,            ///< [in] Binary scan operator
+        T              &warp_aggregate)    ///< [out] Warp-wide aggregate reduction of input items.
+    {
+        T inclusive_output;
+        InclusiveReverseScan(input, inclusive_output, scan_op);
+        warp_aggregate = cub::ShuffleIndex<LOGICAL_WARP_THREADS>(inclusive_output, 0, member_mask);
+        // initial value unknown
+        exclusive_output = cub::ShuffleDown<LOGICAL_WARP_THREADS>(
+            inclusive_output, 1, LOGICAL_WARP_THREADS - 1, member_mask
+        );
+    }
+
+    /**
+     * \brief Computes both inclusive and exclusive reverse scans using the specified binary scan functor across the calling warp.  Because no initial value is supplied, the \p exclusive_output computed for the last <em>warp-lane</em> is undefined.
+     */
+    template <typename ScanOpT>
+    __device__ __forceinline__ void ReverseScan(
+        T               input,              ///< [in] Calling thread's input item.
+        T               &inclusive_output,  ///< [out] Calling thread's inclusive-scan output item.
+        T               &exclusive_output,  ///< [out] Calling thread's exclusive-scan output item.
+        ScanOpT         scan_op)            ///< [in] Binary scan operator
+    {
+        InclusiveReverseScan(input, inclusive_output, scan_op);
+        // initial value unknown
+        exclusive_output = cub::ShuffleDown<LOGICAL_WARP_THREADS>(
+            inclusive_output, 1, LOGICAL_WARP_THREADS - 1, member_mask
+        );
+    }
+
+};
+
+/**
+ * \brief BlockReverseScan provides variants of raking-based parallel postfix scan across a CUDA thread block.
+ */
+template <
+    typename    T,              ///< Data type being scanned
+    int         BLOCK_DIM_X,    ///< The thread block length in threads along the X dimension
+    bool        MEMOIZE=false   ///< Whether or not to buffer outer raking scan partials to incur fewer shared memory reads at the expense of higher register pressure
+    >
+struct BlockReverseScan {
+    //---------------------------------------------------------------------
+    // Types and constants
+    //---------------------------------------------------------------------
+
+    /// Constants
+    /// The thread block size in threads
+    static constexpr int BLOCK_THREADS = BLOCK_DIM_X;
+
+    /// Layout type for padded thread block raking grid
+    using BlockRakingLayout = cub::BlockRakingLayout<T, BLOCK_THREADS>;
+    // The number of reduction elements is not a multiple of the number of raking threads for now
+    static_assert(BlockRakingLayout::UNGUARDED);
+
+    /// Number of raking threads
+    static constexpr int RAKING_THREADS = BlockRakingLayout::RAKING_THREADS;
+    /// Number of raking elements per warp synchronous raking thread
+    static constexpr int SEGMENT_LENGTH = BlockRakingLayout::SEGMENT_LENGTH;
+    /// Cooperative work can be entirely warp synchronous
+    static constexpr bool WARP_SYNCHRONOUS = (int(BLOCK_THREADS) == int(RAKING_THREADS));
+
+    ///  WarpReverseScan utility type
+    using WarpReverseScan = WarpReverseScan<T, RAKING_THREADS>;
+
+    /// Shared memory storage layout type
+    struct _TempStorage {
+        typename BlockRakingLayout::TempStorage raking_grid;     ///< Padded thread block raking grid
+    };
+
+
+    /// Alias wrapper allowing storage to be unioned
+    struct TempStorage : cub::Uninitialized<_TempStorage> {};
+
+
+    //---------------------------------------------------------------------
+    // Per-thread fields
+    //---------------------------------------------------------------------
+
+    // Thread fields
+    _TempStorage    &temp_storage;
+    unsigned int    linear_tid;
+    T               cached_segment[SEGMENT_LENGTH];
+
+
+    //---------------------------------------------------------------------
+    // Utility methods
+    //---------------------------------------------------------------------
+
+    /// Performs upsweep raking reduction, returning the aggregate
+    template <typename ScanOp>
+    __device__ __forceinline__ T Upsweep(ScanOp scan_op) {
+        T *smem_raking_ptr = BlockRakingLayout::RakingPtr(temp_storage.raking_grid, linear_tid);
+        // Read data into registers
+        #pragma unroll
+        for (int i = 0; i < SEGMENT_LENGTH; ++i) { cached_segment[i] = smem_raking_ptr[i]; }
+        T raking_partial = cached_segment[SEGMENT_LENGTH - 1];
+        #pragma unroll
+        for (int i = SEGMENT_LENGTH - 2; i >= 0; --i) {
+            raking_partial = scan_op(raking_partial, cached_segment[i]);
+        }
+        return raking_partial;
+    }
+
+
+    /// Performs exclusive downsweep raking scan
+    template <typename ScanOp>
+    __device__ __forceinline__ void ExclusiveDownsweep(
+        ScanOp          scan_op,
+        T               raking_partial)
+    {
+        T *smem_raking_ptr = BlockRakingLayout::RakingPtr(temp_storage.raking_grid, linear_tid);
+        // Read data back into registers
+        if (!MEMOIZE) {
+            #pragma unroll
+            for (int i = 0; i < SEGMENT_LENGTH; ++i) { cached_segment[i] = smem_raking_ptr[i]; }
+        }
+        ThreadReverseScanExclusive(cached_segment, cached_segment, scan_op, raking_partial);
+        // Write data back to smem
+        #pragma unroll
+        for (int i = 0; i < SEGMENT_LENGTH; ++i) { smem_raking_ptr[i] = cached_segment[i]; }
+    }
+
+
+    //---------------------------------------------------------------------
+    // Constructors
+    //---------------------------------------------------------------------
+
+    /// Constructor
+    __device__ __forceinline__ BlockReverseScan(
+        TempStorage &temp_storage)
+    :
+        temp_storage(temp_storage.Alias()),
+        linear_tid(cub::RowMajorTid(BLOCK_DIM_X, 1, 1))
+    {}
+
+
+    /// Computes an exclusive thread block-wide postfix scan using the specified binary \p scan_op functor.  Each thread contributes one input element.  the call-back functor \p block_postfix_callback_op is invoked by the first warp in the block, and the value returned by <em>lane</em><sub>0</sub> in that warp is used as the "seed" value that logically postfixes the thread block's scan inputs.  Also provides every thread with the block-wide \p block_aggregate of all inputs.
+    template <
+        typename ScanOp,
+        typename BlockPostfixCallbackOp>
+    __device__ __forceinline__ void ExclusiveReverseScan(
+        T                       input,                          ///< [in] Calling thread's input item
+        T                       &exclusive_output,              ///< [out] Calling thread's output item (may be aliased to \p input)
+        ScanOp                  scan_op,                        ///< [in] Binary scan operator
+        BlockPostfixCallbackOp  &block_postfix_callback_op)     ///< [in-out] <b>[<em>warp</em><sub>0</sub> only]</b> Call-back functor for specifying a thread block-wide postfix to be applied to all inputs.
+    {
+        if (WARP_SYNCHRONOUS) {
+            // Short-circuit directly to warp-synchronous scan
+            T block_aggregate;
+            WarpReverseScan warp_scan;
+            warp_scan.ExclusiveReverseScan(input, exclusive_output, scan_op, block_aggregate);
+            // Obtain warp-wide postfix in lane0, then broadcast to other lanes
+            T block_postfix = block_postfix_callback_op(block_aggregate);
+            block_postfix = warp_scan.Broadcast(block_postfix, 0);
+            exclusive_output = linear_tid == BLOCK_THREADS - 1 ? block_postfix : scan_op(block_postfix, exclusive_output);
+        } else {
+            // Place thread partial into shared memory raking grid
+            T *placement_ptr = BlockRakingLayout::PlacementPtr(temp_storage.raking_grid, linear_tid);
+            detail::uninitialized_copy(placement_ptr, input);
+            cub::CTA_SYNC();
+            // Reduce parallelism down to just raking threads
+            if (linear_tid < RAKING_THREADS) {
+                WarpReverseScan warp_scan;
+                // Raking upsweep reduction across shared partials
+                T upsweep_partial = Upsweep(scan_op);
+                // Warp-synchronous scan
+                T exclusive_partial, block_aggregate;
+                warp_scan.ExclusiveReverseScan(upsweep_partial, exclusive_partial, scan_op, block_aggregate);
+                // Obtain block-wide postfix in lane0, then broadcast to other lanes
+                T block_postfix = block_postfix_callback_op(block_aggregate);
+                block_postfix = warp_scan.Broadcast(block_postfix, 0);
+                // Update postfix with warpscan exclusive partial
+                T downsweep_postfix = linear_tid == RAKING_THREADS - 1
+                    ? block_postfix : scan_op(block_postfix, exclusive_partial);
+                // Exclusive raking downsweep scan
+                ExclusiveDownsweep(scan_op, downsweep_postfix);
+            }
+            cub::CTA_SYNC();
+            // Grab thread postfix from shared memory
+            exclusive_output = *placement_ptr;
+
+            // // Compute warp scan in each warp.
+            // // The exclusive output from the last lane in each warp is invalid.
+            // T inclusive_output;
+            // WarpReverseScan warp_scan;
+            // warp_scan.ReverseScan(input, inclusive_output, exclusive_output, scan_op);
+
+            // // Compute the warp-wide postfix and block-wide aggregate for each warp.  Warp postfix for the last warp is invalid.
+            // T block_aggregate;
+            // T warp_postfix = ComputeWarpPostfix(scan_op, inclusive_output, block_aggregate);
+
+            // // Apply warp postfix to our lane's partial
+            // if (warp_id != 0) {
+            //     exclusive_output = scan_op(warp_postfix, exclusive_output);
+            //     if (lane_id == 0) { exclusive_output = warp_postfix; }
+            // }
+
+            // // Use the first warp to determine the thread block postfix, returning the result in lane0
+            // if (warp_id == 0) {
+            //     T block_postfix = block_postfix_callback_op(block_aggregate);
+            //     if (lane_id == 0) {
+            //         // Share the postfix with all threads
+            //         detail::uninitialized_copy(&temp_storage.block_postfix,
+            //                                   block_postfix);
+
+            //         exclusive_output = block_postfix; // The block postfix is the exclusive output for tid0
+            //     }
+            // }
+
+            // cub::CTA_SYNC();
+
+            // // Incorporate thread block postfix into outputs
+            // T block_postfix = temp_storage.block_postfix;
+            // if (linear_tid > 0) { exclusive_output = scan_op(block_postfix, exclusive_output); }
+        }
+    }
+
+
+    /**
+     * \brief Computes an inclusive block-wide postfix scan using the specified binary \p scan_op functor.  Each thread contributes an array of consecutive input elements.  the call-back functor \p block_postfix_callback_op is invoked by the first warp in the block, and the value returned by <em>lane</em><sub>0</sub> in that warp is used as the "seed" value that logically postfixes the thread block's scan inputs.  Also provides every thread with the block-wide \p block_aggregate of all inputs.
+     */
+    template <
+        int             ITEMS_PER_THREAD,
+        typename        ScanOp,
+        typename        BlockPostfixCallbackOp>
+    __device__ __forceinline__ void InclusiveReverseScan(
+        T                       (&input)[ITEMS_PER_THREAD],     ///< [in] Calling thread's input items
+        T                       (&output)[ITEMS_PER_THREAD],    ///< [out] Calling thread's output items (may be aliased to \p input)
+        ScanOp                  scan_op,                        ///< [in] Binary scan functor
+        BlockPostfixCallbackOp   &block_postfix_callback_op)    ///< [in-out] <b>[<em>warp</em><sub>0</sub> only]</b> Call-back functor for specifying a block-wide postfix to be applied to the logical input sequence.
+    {
+        // Reduce consecutive thread items in registers
+        T thread_postfix = ThreadReverseReduce(input, scan_op);
+        // Exclusive thread block-scan
+        ExclusiveReverseScan(thread_postfix, thread_postfix, scan_op, block_postfix_callback_op);
+        // Inclusive scan in registers with postfix as seed
+        ThreadReverseScanInclusive(input, output, scan_op, thread_postfix);
+    }
+
+};

mamba/csrc/selective_scan/selective_scan.cpp

@@ -0,0 +1,497 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#include <ATen/cuda/CUDAContext.h>
+#include <c10/cuda/CUDAGuard.h>
+#include <torch/extension.h>
+#include <vector>
+
+#include "selective_scan.h"
+
+#define CHECK_SHAPE(x, ...) TORCH_CHECK(x.sizes() == torch::IntArrayRef({__VA_ARGS__}), #x " must have shape (" #__VA_ARGS__ ")")
+
+#define DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(ITYPE, NAME, ...)                    \
+    if (ITYPE == at::ScalarType::Half) {                                            \
+        using input_t = at::Half;                                                   \
+        __VA_ARGS__();                                                              \
+    } else if (ITYPE == at::ScalarType::BFloat16) {                                 \
+        using input_t = at::BFloat16;                                               \
+        __VA_ARGS__();                                                              \
+    } else if (ITYPE == at::ScalarType::Float)  {                                   \
+        using input_t = float;                                                      \
+        __VA_ARGS__();                                                              \
+    } else {                                                                        \
+        AT_ERROR(#NAME, " not implemented for input type '", toString(ITYPE), "'"); \
+    }
+
+#define DISPATCH_WTYPE_FLOAT_AND_HALF_AND_BF16(WTYPE, NAME, ...)                     \
+    if (WTYPE == at::ScalarType::Half) {                                             \
+        using weight_t = at::Half;                                                   \
+        __VA_ARGS__();                                                               \
+    } else if (WTYPE == at::ScalarType::BFloat16) {                                  \
+        using weight_t = at::BFloat16;                                               \
+        __VA_ARGS__();                                                               \
+    } else if (WTYPE == at::ScalarType::Float)  {                                    \
+        using weight_t = float;                                                      \
+        __VA_ARGS__();                                                               \
+    } else {                                                                         \
+        AT_ERROR(#NAME, " not implemented for weight type '", toString(WTYPE), "'"); \
+    }
+
+#define DISPATCH_WTYPE_FLOAT_AND_COMPLEX(WTYPE, NAME, ...)                           \
+    if (WTYPE == at::ScalarType::Float) {                                            \
+       using weight_t = float;                                                       \
+        __VA_ARGS__();                                                               \
+    } else if (WTYPE == at::ScalarType::ComplexFloat) {                              \
+        using weight_t = c10::complex<float>;                                        \
+        __VA_ARGS__();                                                               \
+    } else {                                                                         \
+        AT_ERROR(#NAME, " not implemented for weight type '", toString(WTYPE), "'"); \
+    }
+
+template<typename input_t, typename weight_t>
+void selective_scan_fwd_cuda(SSMParamsBase &params, cudaStream_t stream);
+
+template <typename input_t, typename weight_t>
+void selective_scan_bwd_cuda(SSMParamsBwd &params, cudaStream_t stream);
+
+void set_ssm_params_fwd(SSMParamsBase &params,
+                        // sizes
+                        const size_t batch,
+                        const size_t dim,
+                        const size_t seqlen,
+                        const size_t dstate,
+                        const size_t n_groups,
+                        const size_t n_chunks,
+                        const bool is_variable_B,
+                        const bool is_variable_C,
+                        // device pointers
+                        const at::Tensor u,
+                        const at::Tensor delta,
+                        const at::Tensor A,
+                        const at::Tensor B,
+                        const at::Tensor C,
+                        const at::Tensor out,
+                        const at::Tensor z,
+                        const at::Tensor out_z,
+                        void* D_ptr,
+                        void* delta_bias_ptr,
+                        void* x_ptr,
+                        bool has_z,
+                        bool delta_softplus) {
+
+    // Reset the parameters
+    memset(&params, 0, sizeof(params));
+
+    params.batch = batch;
+    params.dim = dim;
+    params.seqlen = seqlen;
+    params.dstate = dstate;
+    params.n_groups = n_groups;
+    params.n_chunks = n_chunks;
+    params.dim_ngroups_ratio = dim / n_groups;
+
+    params.delta_softplus = delta_softplus;
+
+    params.is_variable_B = is_variable_B;
+    params.is_variable_C = is_variable_C;
+
+    // Set the pointers and strides.
+    params.u_ptr = u.data_ptr();
+    params.delta_ptr = delta.data_ptr();
+    params.A_ptr = A.data_ptr();
+    params.B_ptr = B.data_ptr();
+    params.C_ptr = C.data_ptr();
+    params.D_ptr = D_ptr;
+    params.delta_bias_ptr = delta_bias_ptr;
+    params.out_ptr = out.data_ptr();
+    params.x_ptr = x_ptr;
+    params.z_ptr = has_z ? z.data_ptr() : nullptr;
+    params.out_z_ptr = has_z ? out_z.data_ptr() : nullptr;
+    // All stride are in elements, not bytes.
+    params.A_d_stride = A.stride(0);
+    params.A_dstate_stride = A.stride(1);
+    if (!is_variable_B) {
+        params.B_d_stride = B.stride(0);
+    } else {
+        params.B_batch_stride = B.stride(0);
+        params.B_group_stride = B.stride(1);
+    }
+    params.B_dstate_stride = !is_variable_B ? B.stride(1) : B.stride(2);
+    if (!is_variable_C) {
+        params.C_d_stride = C.stride(0);
+    } else {
+        params.C_batch_stride = C.stride(0);
+        params.C_group_stride = C.stride(1);
+    }
+    params.C_dstate_stride = !is_variable_C ? C.stride(1) : C.stride(2);
+    params.u_batch_stride = u.stride(0);
+    params.u_d_stride = u.stride(1);
+    params.delta_batch_stride = delta.stride(0);
+    params.delta_d_stride = delta.stride(1);
+    if (has_z) {
+        params.z_batch_stride = z.stride(0);
+        params.z_d_stride = z.stride(1);
+        params.out_z_batch_stride = out_z.stride(0);
+        params.out_z_d_stride = out_z.stride(1);
+    }
+    params.out_batch_stride = out.stride(0);
+    params.out_d_stride = out.stride(1);
+}
+
+void set_ssm_params_bwd(SSMParamsBwd &params,
+                        // sizes
+                        const size_t batch,
+                        const size_t dim,
+                        const size_t seqlen,
+                        const size_t dstate,
+                        const size_t n_groups,
+                        const size_t n_chunks,
+                        const bool is_variable_B,
+                        const bool is_variable_C,
+                        // device pointers
+                        const at::Tensor u,
+                        const at::Tensor delta,
+                        const at::Tensor A,
+                        const at::Tensor B,
+                        const at::Tensor C,
+                        const at::Tensor z,
+                        const at::Tensor out,
+                        const at::Tensor out_z,
+                        void* D_ptr,
+                        void* delta_bias_ptr,
+                        void* x_ptr,
+                        const at::Tensor dout,
+                        const at::Tensor du,
+                        const at::Tensor ddelta,
+                        const at::Tensor dA,
+                        const at::Tensor dB,
+                        const at::Tensor dC,
+                        const at::Tensor dz,
+                        void* dD_ptr,
+                        void* ddelta_bias_ptr,
+                        bool has_z,
+                        bool delta_softplus,
+                        bool recompute_out_z) {
+    // Pass in "dout" instead of "out", we're not gonna use "out" unless we have z
+    set_ssm_params_fwd(params, batch, dim, seqlen, dstate, n_groups, n_chunks, is_variable_B, is_variable_C,
+                       u, delta, A, B, C, has_z ? out : dout,
+                       has_z ? z : dout,
+                       // If not recompute_out_z, pass dout instead of out_z.
+                       // This won't be used by the bwd kernel
+                       recompute_out_z ? out_z : dout,
+                       D_ptr, delta_bias_ptr, x_ptr, has_z, delta_softplus);
+    if (!recompute_out_z) { params.out_z_ptr = nullptr; }
+
+    // Set the pointers and strides.
+    params.dout_ptr = dout.data_ptr();
+    params.du_ptr = du.data_ptr();
+    params.dA_ptr = dA.data_ptr();
+    params.dB_ptr = dB.data_ptr();
+    params.dC_ptr = dC.data_ptr();
+    params.dD_ptr = dD_ptr;
+    params.ddelta_ptr = ddelta.data_ptr();
+    params.ddelta_bias_ptr = ddelta_bias_ptr;
+    params.dz_ptr = has_z ? dz.data_ptr() : nullptr;
+    // All stride are in elements, not bytes.
+    params.dout_batch_stride = dout.stride(0);
+    params.dout_d_stride = dout.stride(1);
+    params.dA_d_stride = dA.stride(0);
+    params.dA_dstate_stride = dA.stride(1);
+    if (!is_variable_B) {
+        params.dB_d_stride = dB.stride(0);
+    } else {
+        params.dB_batch_stride = dB.stride(0);
+        params.dB_group_stride = dB.stride(1);
+    }
+    params.dB_dstate_stride = !is_variable_B ? dB.stride(1) : dB.stride(2);
+    if (!is_variable_C) {
+        params.dC_d_stride = dC.stride(0);
+    } else {
+        params.dC_batch_stride = dC.stride(0);
+        params.dC_group_stride = dC.stride(1);
+    }
+    params.dC_dstate_stride = !is_variable_C ? dC.stride(1) : dC.stride(2);
+    params.du_batch_stride = du.stride(0);
+    params.du_d_stride = du.stride(1);
+    params.ddelta_batch_stride = ddelta.stride(0);
+    params.ddelta_d_stride = ddelta.stride(1);
+    if (has_z) {
+        params.dz_batch_stride = dz.stride(0);
+        params.dz_d_stride = dz.stride(1);
+    }
+}
+
+std::vector<at::Tensor>
+selective_scan_fwd(const at::Tensor &u, const at::Tensor &delta,
+                  const at::Tensor &A, const at::Tensor &B, const at::Tensor &C,
+                  const c10::optional<at::Tensor> &D_,
+                  const c10::optional<at::Tensor> &z_,
+                  const c10::optional<at::Tensor> &delta_bias_,
+                  bool delta_softplus) {
+    auto input_type = u.scalar_type();
+    auto weight_type = A.scalar_type();
+    TORCH_CHECK(input_type == at::ScalarType::Float || input_type == at::ScalarType::Half || input_type == at::ScalarType::BFloat16);
+    TORCH_CHECK(weight_type == at::ScalarType::Float || weight_type == at::ScalarType::ComplexFloat);
+
+    const bool is_variable_B = B.dim() >= 3;
+    const bool is_variable_C = C.dim() >= 3;
+    const bool is_complex = weight_type == at::ScalarType::ComplexFloat;
+
+    TORCH_CHECK(delta.scalar_type() == input_type);
+    TORCH_CHECK(B.scalar_type() == (!is_variable_B ? weight_type : input_type));
+    TORCH_CHECK(C.scalar_type() == (!is_variable_C ? weight_type : input_type));
+
+    TORCH_CHECK(u.is_cuda());
+    TORCH_CHECK(delta.is_cuda());
+    TORCH_CHECK(A.is_cuda());
+    TORCH_CHECK(B.is_cuda());
+    TORCH_CHECK(C.is_cuda());
+
+    TORCH_CHECK(u.stride(-1) == 1);
+    TORCH_CHECK(delta.stride(-1) == 1);
+
+    const auto sizes = u.sizes();
+    const int batch_size = sizes[0];
+    const int dim = sizes[1];
+    const int seqlen = sizes[2];
+    const int dstate = A.size(1);
+    const int n_groups = is_variable_B ? B.size(1) : 1;
+
+    TORCH_CHECK(dstate <= 256, "selective_scan only supports state dimension <= 256");
+
+    CHECK_SHAPE(u, batch_size, dim, seqlen);
+    CHECK_SHAPE(delta, batch_size, dim, seqlen);
+    CHECK_SHAPE(A, dim, dstate);
+    if (!is_variable_B) {
+        CHECK_SHAPE(B, dim, dstate);
+    } else {
+        CHECK_SHAPE(B, batch_size, n_groups, dstate, !is_complex ? seqlen : seqlen * 2);
+        TORCH_CHECK(B.stride(-1) == 1);
+    }
+    if (!is_variable_C) {
+        CHECK_SHAPE(C, dim, dstate);
+    } else {
+        CHECK_SHAPE(C, batch_size, n_groups, dstate, !is_complex ? seqlen: seqlen * 2);
+        TORCH_CHECK(C.stride(-1) == 1);
+    }
+
+    if (D_.has_value()) {
+        auto D = D_.value();
+        TORCH_CHECK(D.scalar_type() == at::ScalarType::Float);
+        TORCH_CHECK(D.is_cuda());
+        TORCH_CHECK(D.stride(-1) == 1);
+        CHECK_SHAPE(D, dim);
+    }
+
+    if (delta_bias_.has_value()) {
+        auto delta_bias = delta_bias_.value();
+        TORCH_CHECK(delta_bias.scalar_type() == at::ScalarType::Float);
+        TORCH_CHECK(delta_bias.is_cuda());
+        TORCH_CHECK(delta_bias.stride(-1) == 1);
+        CHECK_SHAPE(delta_bias, dim);
+    }
+
+    at::Tensor z, out_z;
+    const bool has_z = z_.has_value();
+    if (has_z) {
+        z = z_.value();
+        TORCH_CHECK(z.scalar_type() == input_type);
+        TORCH_CHECK(z.is_cuda());
+        TORCH_CHECK(z.stride(-1) == 1);
+        CHECK_SHAPE(z, batch_size, dim, seqlen);
+        out_z = torch::empty_like(z);
+    }
+
+    const int n_chunks = (seqlen + 2048 - 1) / 2048;
+    // const int n_chunks = (seqlen + 1024 - 1) / 1024;
+    // at::Tensor out = torch::empty_like(u);
+    // Right now u has BHL layout and delta has HBL layout, and we want out to have HBL layout
+    at::Tensor out = torch::empty_like(delta);
+    at::Tensor x;
+    x = torch::empty({batch_size, dim, n_chunks, dstate * 2}, u.options().dtype(weight_type));
+
+    SSMParamsBase params;
+    set_ssm_params_fwd(params, batch_size, dim, seqlen, dstate, n_groups, n_chunks, is_variable_B, is_variable_C,
+                       u, delta, A, B, C, out, z, out_z,
+                       D_.has_value() ? D_.value().data_ptr() : nullptr,
+                       delta_bias_.has_value() ? delta_bias_.value().data_ptr() : nullptr,
+                       x.data_ptr(),
+                       has_z,
+                       delta_softplus);
+
+    // Otherwise the kernel will be launched from cuda:0 device
+    // Cast to char to avoid compiler warning about narrowing
+    at::cuda::CUDAGuard device_guard{(char)u.get_device()};
+    auto stream = at::cuda::getCurrentCUDAStream().stream();
+    DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(u.scalar_type(), "selective_scan_fwd", [&] {
+        DISPATCH_WTYPE_FLOAT_AND_COMPLEX(A.scalar_type(), "selective_scan_fwd", [&] {
+            selective_scan_fwd_cuda<input_t, weight_t>(params, stream);
+        });
+    });
+    std::vector<at::Tensor> result = {out, x};
+    if (has_z) { result.push_back(out_z); }
+    return result;
+}
+
+std::vector<at::Tensor>
+selective_scan_bwd(const at::Tensor &u, const at::Tensor &delta,
+                  const at::Tensor &A, const at::Tensor &B, const at::Tensor &C,
+                  const c10::optional<at::Tensor> &D_,
+                  const c10::optional<at::Tensor> &z_,
+                  const c10::optional<at::Tensor> &delta_bias_,
+                  const at::Tensor &dout,
+                  const c10::optional<at::Tensor> &x_,
+                  const c10::optional<at::Tensor> &out_,
+                  c10::optional<at::Tensor> &dz_,
+                  bool delta_softplus,
+                  bool recompute_out_z) {
+    auto input_type = u.scalar_type();
+    auto weight_type = A.scalar_type();
+    TORCH_CHECK(input_type == at::ScalarType::Float || input_type == at::ScalarType::Half || input_type == at::ScalarType::BFloat16);
+    TORCH_CHECK(weight_type == at::ScalarType::Float || weight_type == at::ScalarType::ComplexFloat);
+
+    const bool is_variable_B = B.dim() >= 3;
+    const bool is_variable_C = C.dim() >= 3;
+    const bool is_complex = weight_type == at::ScalarType::ComplexFloat;
+
+    TORCH_CHECK(delta.scalar_type() == input_type);
+    TORCH_CHECK(B.scalar_type() == (!is_variable_B ? weight_type : input_type));
+    TORCH_CHECK(C.scalar_type() == (!is_variable_C ? weight_type : input_type));
+    TORCH_CHECK(dout.scalar_type() == input_type);
+
+    TORCH_CHECK(u.is_cuda());
+    TORCH_CHECK(delta.is_cuda());
+    TORCH_CHECK(A.is_cuda());
+    TORCH_CHECK(B.is_cuda());
+    TORCH_CHECK(C.is_cuda());
+    TORCH_CHECK(dout.is_cuda());
+
+    TORCH_CHECK(u.stride(-1) == 1);
+    TORCH_CHECK(delta.stride(-1) == 1);
+    TORCH_CHECK(dout.stride(-1) == 1);
+
+    const auto sizes = u.sizes();
+    const int batch_size = sizes[0];
+    const int dim = sizes[1];
+    const int seqlen = sizes[2];
+    const int dstate = A.size(1);
+    const int n_groups = is_variable_B ? B.size(1) : 1;
+
+    TORCH_CHECK(dstate <= 256, "selective_scan only supports state dimension <= 256");
+
+    CHECK_SHAPE(u, batch_size, dim, seqlen);
+    CHECK_SHAPE(delta, batch_size, dim, seqlen);
+    CHECK_SHAPE(A, dim, dstate);
+    if (!is_variable_B) {
+        CHECK_SHAPE(B, dim, dstate);
+    } else {
+        CHECK_SHAPE(B, batch_size, n_groups, dstate, !is_complex ? seqlen : seqlen * 2);
+        TORCH_CHECK(B.stride(-1) == 1);
+    }
+    if (!is_variable_C) {
+        CHECK_SHAPE(C, dim, dstate);
+    } else {
+        CHECK_SHAPE(C, batch_size, n_groups, dstate, !is_complex ? seqlen: seqlen * 2);
+        TORCH_CHECK(C.stride(-1) == 1);
+    }
+    CHECK_SHAPE(dout, batch_size, dim, seqlen);
+
+    if (D_.has_value()) {
+        auto D = D_.value();
+        TORCH_CHECK(D.scalar_type() == at::ScalarType::Float);
+        TORCH_CHECK(D.is_cuda());
+        TORCH_CHECK(D.stride(-1) == 1);
+        CHECK_SHAPE(D, dim);
+    }
+
+    if (delta_bias_.has_value()) {
+        auto delta_bias = delta_bias_.value();
+        TORCH_CHECK(delta_bias.scalar_type() == at::ScalarType::Float);
+        TORCH_CHECK(delta_bias.is_cuda());
+        TORCH_CHECK(delta_bias.stride(-1) == 1);
+        CHECK_SHAPE(delta_bias, dim);
+    }
+
+    at::Tensor z, out, dz, out_z;
+    const bool has_z = z_.has_value();
+    if (has_z) {
+        z = z_.value();
+        TORCH_CHECK(z.scalar_type() == input_type);
+        TORCH_CHECK(z.is_cuda());
+        TORCH_CHECK(z.stride(-1) == 1);
+        CHECK_SHAPE(z, batch_size, dim, seqlen);
+
+        TORCH_CHECK(out_.has_value());
+        out = out_.value();
+        TORCH_CHECK(out.scalar_type() == input_type);
+        TORCH_CHECK(out.is_cuda());
+        TORCH_CHECK(out.stride(-1) == 1);
+        CHECK_SHAPE(out, batch_size, dim, seqlen);
+
+        if (dz_.has_value()) {
+            dz = dz_.value();
+            TORCH_CHECK(dz.scalar_type() == input_type);
+            TORCH_CHECK(dz.is_cuda());
+            TORCH_CHECK(dz.stride(-1) == 1);
+            CHECK_SHAPE(dz, batch_size, dim, seqlen);
+        } else {
+            dz = torch::empty_like(z);
+        }
+        if (recompute_out_z) {
+            out_z = torch::empty_like(out);
+        }
+    }
+
+    const int n_chunks = (seqlen + 2048 - 1) / 2048;
+    // const int n_chunks = (seqlen + 1024 - 1) / 1024;
+    if (n_chunks > 1) { TORCH_CHECK(x_.has_value()); }
+    if (x_.has_value()) {
+        auto x = x_.value();
+        TORCH_CHECK(x.scalar_type() == weight_type);
+        TORCH_CHECK(x.is_cuda());
+        TORCH_CHECK(x.is_contiguous());
+        CHECK_SHAPE(x, batch_size, dim, n_chunks, 2 * dstate);
+    }
+
+    at::Tensor du = torch::empty_like(u);
+    at::Tensor ddelta = torch::empty_like(delta);
+    at::Tensor dA = torch::zeros_like(A);
+    at::Tensor dB = !is_variable_B ? torch::zeros_like(B) : torch::zeros_like(B, B.options().dtype(torch::kFloat32));
+    at::Tensor dC = !is_variable_C ? torch::zeros_like(C) : torch::zeros_like(C, C.options().dtype(torch::kFloat32));
+    at::Tensor dD;
+    if (D_.has_value()) { dD = torch::zeros_like(D_.value()); }
+    at::Tensor ddelta_bias;
+    if (delta_bias_.has_value()) { ddelta_bias = torch::zeros_like(delta_bias_.value()); }
+
+    SSMParamsBwd params;
+    set_ssm_params_bwd(params, batch_size, dim, seqlen, dstate, n_groups, n_chunks, is_variable_B, is_variable_C,
+                       u, delta, A, B, C, z, out, out_z,
+                       D_.has_value() ? D_.value().data_ptr() : nullptr,
+                       delta_bias_.has_value() ? delta_bias_.value().data_ptr() : nullptr,
+                       x_.has_value() ? x_.value().data_ptr() : nullptr,
+                       dout, du, ddelta, dA, dB, dC, dz,
+                       D_.has_value() ? dD.data_ptr() : nullptr,
+                       delta_bias_.has_value() ? ddelta_bias.data_ptr() : nullptr,
+                       has_z, delta_softplus, recompute_out_z);
+
+    // Otherwise the kernel will be launched from cuda:0 device
+    // Cast to char to avoid compiler warning about narrowing
+    at::cuda::CUDAGuard device_guard{(char)u.get_device()};
+    auto stream = at::cuda::getCurrentCUDAStream().stream();
+    DISPATCH_ITYPE_FLOAT_AND_HALF_AND_BF16(u.scalar_type(), "selective_scan_bwd", [&] {
+        DISPATCH_WTYPE_FLOAT_AND_COMPLEX(A.scalar_type(), "selective_scan_bwd", [&] {
+            selective_scan_bwd_cuda<input_t, weight_t>(params, stream);
+        });
+    });
+    std::vector<at::Tensor> result = {du, ddelta, dA, dB.to(B.dtype()), dC.to(C.dtype()), dD, ddelta_bias};
+    if (has_z) { result.push_back(dz); }
+    if (recompute_out_z) { result.push_back(out_z); }
+    return result;
+}
+
+PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
+    m.def("fwd", &selective_scan_fwd, "Selective scan forward");
+    m.def("bwd", &selective_scan_bwd, "Selective scan backward");
+}

mamba/csrc/selective_scan/selective_scan.h

@@ -0,0 +1,101 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct SSMScanParamsBase {
+    using index_t = uint32_t;
+
+    int batch, seqlen, n_chunks;
+    index_t a_batch_stride;
+    index_t b_batch_stride;
+    index_t out_batch_stride;
+
+    // Common data pointers.
+    void *__restrict__ a_ptr;
+    void *__restrict__ b_ptr;
+    void *__restrict__ out_ptr;
+    void *__restrict__ x_ptr;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct SSMParamsBase {
+    using index_t = uint32_t;
+
+    int batch, dim, seqlen, dstate, n_groups, n_chunks;
+    int dim_ngroups_ratio;
+    bool is_variable_B;
+    bool is_variable_C;
+
+    bool delta_softplus;
+
+    index_t A_d_stride;
+    index_t A_dstate_stride;
+    index_t B_batch_stride;
+    index_t B_d_stride;
+    index_t B_dstate_stride;
+    index_t B_group_stride;
+    index_t C_batch_stride;
+    index_t C_d_stride;
+    index_t C_dstate_stride;
+    index_t C_group_stride;
+    index_t u_batch_stride;
+    index_t u_d_stride;
+    index_t delta_batch_stride;
+    index_t delta_d_stride;
+    index_t z_batch_stride;
+    index_t z_d_stride;
+    index_t out_batch_stride;
+    index_t out_d_stride;
+    index_t out_z_batch_stride;
+    index_t out_z_d_stride;
+
+    // Common data pointers.
+    void *__restrict__ A_ptr;
+    void *__restrict__ B_ptr;
+    void *__restrict__ C_ptr;
+    void *__restrict__ D_ptr;
+    void *__restrict__ u_ptr;
+    void *__restrict__ delta_ptr;
+    void *__restrict__ delta_bias_ptr;
+    void *__restrict__ out_ptr;
+    void *__restrict__ x_ptr;
+    void *__restrict__ z_ptr;
+    void *__restrict__ out_z_ptr;
+};
+
+struct SSMParamsBwd: public SSMParamsBase {
+    index_t dout_batch_stride;
+    index_t dout_d_stride;
+    index_t dA_d_stride;
+    index_t dA_dstate_stride;
+    index_t dB_batch_stride;
+    index_t dB_group_stride;
+    index_t dB_d_stride;
+    index_t dB_dstate_stride;
+    index_t dC_batch_stride;
+    index_t dC_group_stride;
+    index_t dC_d_stride;
+    index_t dC_dstate_stride;
+    index_t du_batch_stride;
+    index_t du_d_stride;
+    index_t dz_batch_stride;
+    index_t dz_d_stride;
+    index_t ddelta_batch_stride;
+    index_t ddelta_d_stride;
+
+    // Common data pointers.
+    void *__restrict__ dout_ptr;
+    void *__restrict__ dA_ptr;
+    void *__restrict__ dB_ptr;
+    void *__restrict__ dC_ptr;
+    void *__restrict__ dD_ptr;
+    void *__restrict__ du_ptr;
+    void *__restrict__ dz_ptr;
+    void *__restrict__ ddelta_ptr;
+    void *__restrict__ ddelta_bias_ptr;
+};

mamba/csrc/selective_scan/selective_scan_bwd_bf16_complex.cu

@@ -0,0 +1,9 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_bwd_kernel.cuh"
+
+template void selective_scan_bwd_cuda<at::BFloat16, complex_t>(SSMParamsBwd &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_bwd_bf16_real.cu

@@ -0,0 +1,9 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_bwd_kernel.cuh"
+
+template void selective_scan_bwd_cuda<at::BFloat16, float>(SSMParamsBwd &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_bwd_fp16_complex.cu

@@ -0,0 +1,9 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_bwd_kernel.cuh"
+
+template void selective_scan_bwd_cuda<at::Half, complex_t>(SSMParamsBwd &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_bwd_fp16_real.cu

@@ -0,0 +1,9 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_bwd_kernel.cuh"
+
+template void selective_scan_bwd_cuda<at::Half, float>(SSMParamsBwd &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_bwd_fp32_complex.cu

@@ -0,0 +1,9 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_bwd_kernel.cuh"
+
+template void selective_scan_bwd_cuda<float, complex_t>(SSMParamsBwd &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_bwd_fp32_real.cu

@@ -0,0 +1,9 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_bwd_kernel.cuh"
+
+template void selective_scan_bwd_cuda<float, float>(SSMParamsBwd &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_bwd_kernel.cuh

@@ -0,0 +1,531 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+#include <c10/util/BFloat16.h>
+#include <c10/util/Half.h>
+#include <c10/cuda/CUDAException.h>  // For C10_CUDA_CHECK and C10_CUDA_KERNEL_LAUNCH_CHECK
+#include <ATen/cuda/Atomic.cuh>  // For atomicAdd on complex
+
+#include <cub/block/block_load.cuh>
+#include <cub/block/block_store.cuh>
+#include <cub/block/block_scan.cuh>
+#include <cub/block/block_reduce.cuh>
+
+#include "selective_scan.h"
+#include "selective_scan_common.h"
+#include "reverse_scan.cuh"
+#include "static_switch.h"
+
+template<typename scalar_t> __device__ __forceinline__ scalar_t conj(scalar_t x);
+template<> __device__ __forceinline__ float conj<float>(float x) { return x; }
+template<> __device__ __forceinline__ complex_t conj<complex_t>(complex_t x) { return std::conj(x); }
+
+template<int kNThreads_, int kNItems_, bool kIsEvenLen_, bool kIsVariableB_, bool kIsVariableC_,
+         bool kDeltaSoftplus_, bool kHasZ_, typename input_t_, typename weight_t_>
+struct Selective_Scan_bwd_kernel_traits {
+    static_assert(kNItems_ % 4 == 0);
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr int kNThreads = kNThreads_;
+    static constexpr int kNItems = kNItems_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+    static constexpr int kNElts = kNBytes == 4 ? 4 : std::min(8, kNItems);
+    static_assert(kNItems % kNElts == 0);
+    static constexpr int kNLoads = kNItems / kNElts;
+    static constexpr bool kIsComplex = std::is_same_v<weight_t, complex_t>;
+    static constexpr bool kIsEvenLen = kIsEvenLen_;
+    static constexpr bool kIsVariableB = kIsVariableB_;
+    static constexpr bool kIsVariableC = kIsVariableC_;
+    static constexpr bool kDeltaSoftplus = kDeltaSoftplus_;
+    static constexpr bool kHasZ = kHasZ_;
+    // Setting MinBlocksPerMP to be 3 (instead of 2) for 128 threads with float improves occupancy.
+    // For complex this would lead to massive register spilling, so we keep it at 2.
+    static constexpr int kMinBlocks = kNThreads == 128 && !kIsComplex ? 3 : 2;
+    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
+    using scan_t = std::conditional_t<!kIsComplex, float2, float4>;
+    using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNItems, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadVecT = cub::BlockLoad<vec_t, kNThreads, kNLoads, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadWeightT = cub::BlockLoad<input_t, kNThreads, !kIsComplex ? kNItems : kNItems * 2, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadWeightVecT = cub::BlockLoad<vec_t, kNThreads, !kIsComplex ? kNLoads : kNLoads * 2, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNItems, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    using BlockStoreVecT = cub::BlockStore<vec_t, kNThreads, kNLoads, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    // using BlockScanT = cub::BlockScan<scan_t, kNThreads, cub::BLOCK_SCAN_RAKING_MEMOIZE>;
+    using BlockScanT = cub::BlockScan<scan_t, kNThreads, cub::BLOCK_SCAN_RAKING>;
+    // using BlockScanT = cub::BlockScan<scan_t, kNThreads, cub::BLOCK_SCAN_WARP_SCANS>;
+    using BlockReverseScanT = BlockReverseScan<scan_t, kNThreads>;
+    using BlockReduceT = cub::BlockReduce<scan_t, kNThreads>;
+    using BlockReduceFloatT = cub::BlockReduce<float, kNThreads>;
+    using BlockReduceComplexT = cub::BlockReduce<complex_t, kNThreads>;
+    using BlockExchangeT = cub::BlockExchange<float, kNThreads, !kIsComplex ? kNItems : kNItems * 2>;
+    static constexpr int kSmemIOSize = std::max({sizeof(typename BlockLoadT::TempStorage),
+                                                 sizeof(typename BlockLoadVecT::TempStorage),
+                                                 (int(kIsVariableB) + int(kIsVariableC)) * sizeof(typename BlockLoadWeightT::TempStorage),
+                                                 (int(kIsVariableB) + int(kIsVariableC)) * sizeof(typename BlockLoadWeightVecT::TempStorage),
+                                                 sizeof(typename BlockStoreT::TempStorage),
+                                                 sizeof(typename BlockStoreVecT::TempStorage)});
+    static constexpr int kSmemExchangeSize = (int(kIsVariableB) + int(kIsVariableC)) * sizeof(typename BlockExchangeT::TempStorage);
+    static constexpr int kSmemReduceSize = sizeof(typename BlockReduceT::TempStorage);
+    static constexpr int kSmemSize = kSmemIOSize + kSmemExchangeSize + kSmemReduceSize + sizeof(typename BlockScanT::TempStorage) + sizeof(typename BlockReverseScanT::TempStorage);
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads, Ktraits::kMinBlocks)
+void selective_scan_bwd_kernel(SSMParamsBwd params) {
+    constexpr bool kIsComplex = Ktraits::kIsComplex;
+    constexpr bool kIsVariableB = Ktraits::kIsVariableB;
+    constexpr bool kIsVariableC = Ktraits::kIsVariableC;
+    constexpr bool kDeltaSoftplus = Ktraits::kDeltaSoftplus;
+    constexpr bool kHasZ = Ktraits::kHasZ;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    constexpr int kNItems = Ktraits::kNItems;
+    using input_t = typename Ktraits::input_t;
+    using weight_t = typename Ktraits::weight_t;
+    using scan_t = typename Ktraits::scan_t;
+
+    // Shared memory.
+    extern __shared__ char smem_[];
+    // cast to lvalue reference of expected type
+    // char *smem_loadstorescan = smem_ + 2 * MAX_DSTATE * sizeof(weight_t);
+    // auto& smem_load = reinterpret_cast<typename BlockLoadT::TempStorage&>(smem_ + 2 * MAX_DSTATE * sizeof(weight_t));
+    // auto& smem_load = reinterpret_cast<typename BlockLoadT::TempStorage&>(smem_loadstorescan);
+    auto& smem_load = reinterpret_cast<typename Ktraits::BlockLoadT::TempStorage&>(smem_);
+    auto& smem_load_weight = reinterpret_cast<typename Ktraits::BlockLoadWeightT::TempStorage&>(smem_);
+    auto& smem_load_weight1 = *reinterpret_cast<typename Ktraits::BlockLoadWeightT::TempStorage*>(smem_ + sizeof(typename Ktraits::BlockLoadWeightT::TempStorage));
+    auto& smem_store = reinterpret_cast<typename Ktraits::BlockStoreT::TempStorage&>(smem_);
+    auto& smem_exchange = *reinterpret_cast<typename Ktraits::BlockExchangeT::TempStorage*>(smem_ + Ktraits::kSmemIOSize);
+    auto& smem_exchange1 = *reinterpret_cast<typename Ktraits::BlockExchangeT::TempStorage*>(smem_ + Ktraits::kSmemIOSize + sizeof(typename Ktraits::BlockExchangeT::TempStorage));
+    auto& smem_reduce = *reinterpret_cast<typename Ktraits::BlockReduceT::TempStorage*>(reinterpret_cast<char *>(&smem_exchange) + Ktraits::kSmemExchangeSize);
+    auto& smem_reduce_float = *reinterpret_cast<typename Ktraits::BlockReduceFloatT::TempStorage*>(&smem_reduce);
+    auto& smem_reduce_complex = *reinterpret_cast<typename Ktraits::BlockReduceComplexT::TempStorage*>(&smem_reduce);
+    auto& smem_scan = *reinterpret_cast<typename Ktraits::BlockScanT::TempStorage*>(reinterpret_cast<char *>(&smem_reduce) + Ktraits::kSmemReduceSize);
+    auto& smem_reverse_scan = *reinterpret_cast<typename Ktraits::BlockReverseScanT::TempStorage*>(reinterpret_cast<char *>(&smem_scan) + sizeof(typename Ktraits::BlockScanT::TempStorage));
+    weight_t *smem_delta_a = reinterpret_cast<weight_t *>(smem_ + Ktraits::kSmemSize);
+    scan_t *smem_running_postfix = reinterpret_cast<scan_t *>(smem_delta_a + 2 * MAX_DSTATE + kNThreads);
+    weight_t *smem_da = reinterpret_cast<weight_t *>(smem_running_postfix + MAX_DSTATE);
+    weight_t *smem_dbc = reinterpret_cast<weight_t *>(smem_da + MAX_DSTATE);
+
+    const int batch_id = blockIdx.x;
+    const int dim_id = blockIdx.y;
+    const int group_id = dim_id / (params.dim_ngroups_ratio);
+    input_t *u = reinterpret_cast<input_t *>(params.u_ptr) + batch_id * params.u_batch_stride
+        + dim_id * params.u_d_stride;
+    input_t *delta = reinterpret_cast<input_t *>(params.delta_ptr) + batch_id * params.delta_batch_stride
+        + dim_id * params.delta_d_stride;
+    input_t *dout = reinterpret_cast<input_t *>(params.dout_ptr) + batch_id * params.dout_batch_stride
+        + dim_id * params.dout_d_stride;
+    weight_t *A = reinterpret_cast<weight_t *>(params.A_ptr) + dim_id * params.A_d_stride;
+    weight_t *B = reinterpret_cast<weight_t *>(params.B_ptr) + dim_id * params.B_d_stride;
+    input_t *Bvar = reinterpret_cast<input_t *>(params.B_ptr) + batch_id * params.B_batch_stride + group_id * params.B_group_stride;
+    weight_t *C = reinterpret_cast<weight_t *>(params.C_ptr) + dim_id * params.C_d_stride;
+    input_t *Cvar = reinterpret_cast<input_t *>(params.C_ptr) + batch_id * params.C_batch_stride + group_id * params.C_group_stride;
+    weight_t *dA = reinterpret_cast<weight_t *>(params.dA_ptr) + dim_id * params.dA_d_stride;
+    weight_t *dB = reinterpret_cast<weight_t *>(params.dB_ptr)
+        + (!kIsVariableB ? dim_id * params.dB_d_stride : batch_id * (!kIsComplex ? params.dB_batch_stride : params.dB_batch_stride / 2) + group_id * params.dB_group_stride);
+    weight_t *dC = reinterpret_cast<weight_t *>(params.dC_ptr)
+        + (!kIsVariableC ? dim_id * params.dC_d_stride : batch_id * (!kIsComplex ? params.dC_batch_stride : params.dC_batch_stride / 2) + group_id * params.dC_group_stride);
+    float *dD = params.dD_ptr == nullptr ? nullptr : reinterpret_cast<float *>(params.dD_ptr) + dim_id;
+    float D_val = params.D_ptr == nullptr ? 0 : reinterpret_cast<float *>(params.D_ptr)[dim_id];
+    float *ddelta_bias = params.ddelta_bias_ptr == nullptr ? nullptr : reinterpret_cast<float *>(params.ddelta_bias_ptr) + dim_id;
+    float delta_bias = params.delta_bias_ptr == nullptr ? 0 : reinterpret_cast<float *>(params.delta_bias_ptr)[dim_id];
+    scan_t *x = params.x_ptr == nullptr
+        ? nullptr
+        : reinterpret_cast<scan_t *>(params.x_ptr) + (batch_id * params.dim + dim_id) * (params.n_chunks) * params.dstate;
+    float dD_val = 0;
+    float ddelta_bias_val = 0;
+
+    constexpr int kChunkSize = kNThreads * kNItems;
+    u += (params.n_chunks - 1) * kChunkSize;
+    delta += (params.n_chunks - 1) * kChunkSize;
+    dout += (params.n_chunks - 1) * kChunkSize;
+    Bvar += (params.n_chunks - 1) * kChunkSize * (!kIsComplex ? 1 : 2);
+    Cvar += (params.n_chunks - 1) * kChunkSize * (!kIsComplex ? 1 : 2);
+    for (int chunk = params.n_chunks - 1; chunk >= 0; --chunk) {
+        input_t u_vals[kNItems];
+        input_t delta_vals_load[kNItems];
+        input_t dout_vals_load[kNItems];
+        __syncthreads();
+        load_input<Ktraits>(u, u_vals, smem_load, params.seqlen - chunk * kChunkSize);
+        u -= kChunkSize;
+        __syncthreads();
+        load_input<Ktraits>(delta, delta_vals_load, smem_load, params.seqlen - chunk * kChunkSize);
+        // Will reload delta at the same location if kDeltaSoftplus
+        if constexpr (!kDeltaSoftplus) { delta -= kChunkSize; }
+        __syncthreads();
+        load_input<Ktraits>(dout, dout_vals_load, smem_load, params.seqlen - chunk * kChunkSize);
+        dout -= kChunkSize;
+
+        float dout_vals[kNItems], delta_vals[kNItems];
+        #pragma unroll
+        for (int i = 0; i < kNItems; ++i) {
+            dout_vals[i] = float(dout_vals_load[i]);
+            delta_vals[i] = float(delta_vals_load[i]) + delta_bias;
+            if constexpr (kDeltaSoftplus) {
+                delta_vals[i] = delta_vals[i] <= 20.f ? log1pf(expf(delta_vals[i])) : delta_vals[i];
+            }
+        }
+
+        if constexpr (kHasZ) {
+            input_t *z = reinterpret_cast<input_t *>(params.z_ptr) + batch_id * params.z_batch_stride
+                + dim_id * params.z_d_stride + chunk * kChunkSize;
+            input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
+                + dim_id * params.out_d_stride + chunk * kChunkSize;
+            input_t *dz = reinterpret_cast<input_t *>(params.dz_ptr) + batch_id * params.dz_batch_stride
+                + dim_id * params.dz_d_stride + chunk * kChunkSize;
+            input_t z_vals[kNItems], out_vals[kNItems];
+            __syncthreads();
+            load_input<Ktraits>(z, z_vals, smem_load, params.seqlen - chunk * kChunkSize);
+            __syncthreads();
+            load_input<Ktraits>(out, out_vals, smem_load, params.seqlen - chunk * kChunkSize);
+            float dz_vals[kNItems], z_silu_vals[kNItems];
+            #pragma unroll
+            for (int i = 0; i < kNItems; ++i) {
+                float z_val = z_vals[i];
+                float z_sigmoid_val = 1.0f / (1.0f + expf(-z_val));
+                z_silu_vals[i] = z_val * z_sigmoid_val;
+                dz_vals[i] = dout_vals[i] * float(out_vals[i]) * z_sigmoid_val
+                             * (1.0f + z_val * (1.0f - z_sigmoid_val));
+                dout_vals[i] *= z_silu_vals[i];
+            }
+            __syncthreads();
+            store_output<Ktraits>(dz, dz_vals, smem_store, params.seqlen - chunk * kChunkSize);
+            if (params.out_z_ptr != nullptr) {  // Recompute and store out_z
+                float out_z_vals[kNItems];
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) { out_z_vals[i] = float(out_vals[i]) * z_silu_vals[i]; }
+                // if (blockIdx.x == 0 && blockIdx.y == 0 && threadIdx.x == 0) {
+                    // printf("out_val=%f, z_silu_val = %f, out_z_val = %f\n", float(out_vals[0]), z_silu_vals[0], out_z_vals[0]);
+                // }
+                input_t *out_z = reinterpret_cast<input_t *>(params.out_z_ptr) + batch_id * params.out_z_batch_stride
+                    + dim_id * params.out_z_d_stride + chunk * kChunkSize;
+                __syncthreads();
+                store_output<Ktraits>(out_z, out_z_vals, smem_store, params.seqlen - chunk * kChunkSize);
+            }
+        }
+
+        float du_vals[kNItems];
+        #pragma unroll
+        for (int i = 0; i < kNItems; ++i) { du_vals[i] = D_val * dout_vals[i]; }
+        #pragma unroll
+        for (int i = 0; i < kNItems; ++i) { dD_val += dout_vals[i] * float(u_vals[i]); }
+
+        float ddelta_vals[kNItems] = {0};
+        __syncthreads();
+        for (int state_idx = 0; state_idx < params.dstate; ++state_idx) {
+            const weight_t A_val = A[state_idx * params.A_dstate_stride];
+            // Multiply the real part of A with LOG2E so we can use exp2f instead of expf.
+            weight_t A_scaled;
+            constexpr float kLog2e = M_LOG2E;
+            if constexpr (!kIsComplex) {
+                A_scaled = A_val * kLog2e;
+            } else {
+                A_scaled = complex_t(A_val.real_ * kLog2e, A_val.imag_);
+            }
+            weight_t B_val, C_val;
+            weight_t B_vals[kNItems], C_vals[kNItems];
+            if constexpr (!kIsVariableB) {
+                B_val = B[state_idx * params.B_dstate_stride];
+            } else {
+                load_weight<Ktraits>(Bvar + state_idx * params.B_dstate_stride, B_vals,
+                    smem_load_weight, (params.seqlen - chunk * kChunkSize) * (!kIsComplex ? 1 : 2));
+            }
+            if constexpr (!kIsVariableC) {
+                C_val = C[state_idx * params.C_dstate_stride];
+            } else {
+                auto &smem_load_weight_C = !kIsVariableB ? smem_load_weight : smem_load_weight1;
+                load_weight<Ktraits>(Cvar + state_idx * params.C_dstate_stride, C_vals,
+                    smem_load_weight_C, (params.seqlen - chunk * kChunkSize) * (!kIsComplex ? 1 : 2));
+            }
+            // const weight_t A_val = smem_a[state_idx];
+            scan_t thread_data[kNItems], thread_reverse_data[kNItems];
+            if constexpr (!kIsComplex) {
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    const float delta_a_exp = exp2f(delta_vals[i] * A_scaled);
+                    thread_data[i] = make_float2(delta_a_exp, !kIsVariableB ? delta_vals[i] * float(u_vals[i]) : delta_vals[i] * float(u_vals[i]) * B_vals[i]);
+                    if (i == 0) {
+                        smem_delta_a[threadIdx.x == 0 ? state_idx + (chunk % 2) * MAX_DSTATE : threadIdx.x + 2 * MAX_DSTATE] = delta_a_exp;
+                    } else {
+                        thread_reverse_data[i - 1].x = delta_a_exp;
+                    }
+                    thread_reverse_data[i].y = dout_vals[i] *
+                        (!kIsVariableC
+                         ? (!kIsVariableB ? B_val * C_val : C_val)
+                         : (!kIsVariableB ? B_val * C_vals[i] : C_vals[i]));
+                }
+                __syncthreads();
+                thread_reverse_data[kNItems - 1].x = threadIdx.x == kNThreads - 1
+                    ? (chunk == params.n_chunks - 1 ? 1.f : smem_delta_a[state_idx + ((chunk + 1) % 2) * MAX_DSTATE])
+                    : smem_delta_a[threadIdx.x + 1 + 2 * MAX_DSTATE];
+                // Initialize running total
+                scan_t running_prefix = chunk > 0 && threadIdx.x % 32 == 0 ? x[(chunk - 1) * params.dstate + state_idx] : make_float2(1.f, 0.f);
+                SSMScanPrefixCallbackOp<weight_t> prefix_op(running_prefix);
+                Ktraits::BlockScanT(smem_scan).InclusiveScan(
+                    thread_data, thread_data, SSMScanOp<weight_t>(), prefix_op
+                );
+                scan_t running_postfix = chunk < params.n_chunks - 1 && threadIdx.x % 32 == 0 ? smem_running_postfix[state_idx] : make_float2(1.f, 0.f);
+                SSMScanPrefixCallbackOp<weight_t> postfix_op(running_postfix);
+                Ktraits::BlockReverseScanT(smem_reverse_scan).InclusiveReverseScan(
+                    thread_reverse_data, thread_reverse_data, SSMScanOp<weight_t>(), postfix_op
+                );
+                if (threadIdx.x == 0) { smem_running_postfix[state_idx] = postfix_op.running_prefix; }
+                weight_t dA_val = 0, dBC_val = 0;
+                weight_t dB_vals[kNItems], dC_vals[kNItems];
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    const float dx = thread_reverse_data[i].y;
+                    const float ddelta_u = !kIsVariableB ? dx : dx * B_vals[i];
+                    du_vals[i] += ddelta_u * delta_vals[i];
+                    const float a = thread_data[i].y - (!kIsVariableB ? delta_vals[i] * float(u_vals[i]) : delta_vals[i] * float(u_vals[i]) * B_vals[i]);
+                    ddelta_vals[i] += ddelta_u * float(u_vals[i]) + dx * A_val * a;
+                    dA_val += dx * delta_vals[i] * a;
+                    if constexpr (!kIsVariableB || !kIsVariableC) {
+                        if constexpr (!kIsVariableB) {  // dBC_val is dB_val
+                            dBC_val += dout_vals[i] * (!kIsVariableC ? thread_data[i].y : thread_data[i].y * C_vals[i]);
+                        } else {  // dBC_val is dC_val
+                            dBC_val += dout_vals[i] * thread_data[i].y;
+                        }
+                    }
+                    if constexpr (kIsVariableB) { dB_vals[i] = dx * delta_vals[i] * float(u_vals[i]); }
+                    if constexpr (kIsVariableC) {
+                        dC_vals[i] = dout_vals[i] * (!kIsVariableB ? thread_data[i].y * B_val : thread_data[i].y);
+                    }
+                }
+                // Block-exchange to make the atomicAdd's coalesced, otherwise they're much slower
+                if constexpr (kIsVariableB || kIsVariableC) {
+                    if constexpr (kIsVariableB) {
+                        Ktraits::BlockExchangeT(smem_exchange).BlockedToStriped(dB_vals, dB_vals);
+                    }
+                    if constexpr (kIsVariableC) {
+                        auto &smem_exchange_C = !kIsVariableB ? smem_exchange : smem_exchange1;
+                        Ktraits::BlockExchangeT(smem_exchange_C).BlockedToStriped(dC_vals, dC_vals);
+                    }
+                    const int seqlen_remaining = params.seqlen - chunk * kChunkSize - threadIdx.x;
+                    weight_t *dB_cur = dB + state_idx * params.dB_dstate_stride + chunk * kChunkSize + threadIdx.x;
+                    weight_t *dC_cur = dC + state_idx * params.dC_dstate_stride + chunk * kChunkSize + threadIdx.x;
+                    #pragma unroll
+                    for (int i = 0; i < kNItems; ++i) {
+                        if (i * kNThreads < seqlen_remaining) {
+                            if constexpr (kIsVariableB) { gpuAtomicAdd(dB_cur + i * kNThreads, dB_vals[i]); }
+                            if constexpr (kIsVariableC) { gpuAtomicAdd(dC_cur + i * kNThreads, dC_vals[i]); }
+                        }
+                    }
+                }
+                if constexpr (!kIsVariableB || !kIsVariableC) {
+                    float2 dA_dBC_val = make_float2(dA_val, dBC_val);
+                    dA_dBC_val = Ktraits::BlockReduceT(smem_reduce).Sum(dA_dBC_val);
+                    dA_val = dA_dBC_val.x;
+                    if (threadIdx.x == 0) {
+                        smem_dbc[state_idx] = chunk == params.n_chunks - 1 ? dA_dBC_val.y : dA_dBC_val.y + smem_dbc[state_idx];
+                    }
+                } else {
+                    dA_val = Ktraits::BlockReduceFloatT(smem_reduce_float).Sum(dA_val);
+                }
+                if (threadIdx.x == 0) {
+                    smem_da[state_idx] = chunk == params.n_chunks - 1 ? dA_val : dA_val + smem_da[state_idx];
+                }
+            } else {
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    // Pytorch's implementation of complex exp (which calls thrust) is very slow
+                    complex_t delta_a_exp = cexp2f(delta_vals[i] * A_scaled);
+                    weight_t B_delta_u_val = !kIsVariableB ? delta_vals[i] * float(u_vals[i]) : B_vals[i] * delta_vals[i] * float(u_vals[i]);
+                    thread_data[i] = make_float4(delta_a_exp.real_, delta_a_exp.imag_, B_delta_u_val.real_, B_delta_u_val.imag_);
+                    if (i == 0) {
+                        smem_delta_a[threadIdx.x == 0 ? state_idx + (chunk % 2) * MAX_DSTATE : threadIdx.x + 2 * MAX_DSTATE] = delta_a_exp;
+                    } else {
+                        thread_reverse_data[i - 1].x = delta_a_exp.real_;
+                        thread_reverse_data[i - 1].y = -delta_a_exp.imag_;
+                    }
+                    complex_t dout_BC = 2 * dout_vals[i]
+                        * conj(!kIsVariableC
+                                ? (!kIsVariableB ? B_val * C_val : C_val)
+                                : (!kIsVariableB ? B_val * C_vals[i] : C_vals[i]));
+                    thread_reverse_data[i].z = dout_BC.real_;
+                    thread_reverse_data[i].w = dout_BC.imag_;
+                }
+                __syncthreads();
+                complex_t delta_a_exp = threadIdx.x == kNThreads - 1
+                    ? (chunk == params.n_chunks - 1 ? 1.f : smem_delta_a[state_idx + ((chunk + 1) % 2) * MAX_DSTATE])
+                    : smem_delta_a[threadIdx.x + 1 + 2 * MAX_DSTATE];
+                thread_reverse_data[kNItems - 1].x = delta_a_exp.real_;
+                thread_reverse_data[kNItems - 1].y = -delta_a_exp.imag_;
+                // Initialize running total
+                scan_t running_prefix = chunk > 0 && threadIdx.x % 32 == 0 ? x[(chunk - 1) * params.dstate + state_idx] : make_float4(1.f, 0.f, 0.f, 0.f);
+                SSMScanPrefixCallbackOp<weight_t> prefix_op(running_prefix);
+                Ktraits::BlockScanT(smem_scan).InclusiveScan(
+                    thread_data, thread_data, SSMScanOp<weight_t>(), prefix_op
+                );
+                scan_t running_postfix = chunk < params.n_chunks - 1 && threadIdx.x % 32 == 0 ? smem_running_postfix[state_idx] : make_float4(1.f, 0.f, 0.f, 0.f);
+                SSMScanPrefixCallbackOp<weight_t> postfix_op(running_postfix);
+                Ktraits::BlockReverseScanT(smem_reverse_scan).InclusiveReverseScan(
+                    thread_reverse_data, thread_reverse_data, SSMScanOp<weight_t>(), postfix_op
+                );
+                if (threadIdx.x == 0) { smem_running_postfix[state_idx] = postfix_op.running_prefix; }
+                weight_t dA_val = 0, dBC_val = 0;
+                weight_t dB_vals[kNItems], dC_vals[kNItems];
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    complex_t x = complex_t(thread_data[i].z, thread_data[i].w);
+                    complex_t dx = complex_t(thread_reverse_data[i].z, thread_reverse_data[i].w);
+                    float ddelta_u = !kIsVariableB ? dx.real_ : (dx * conj(B_vals[i])).real_;
+                    if constexpr (!kIsVariableB || !kIsVariableC) {
+                        if constexpr (!kIsVariableB) {  // dBC_val is dB_val
+                            dBC_val += (2 * dout_vals[i]) * conj(!kIsVariableC ? x : x * C_vals[i]);
+                        } else {  // dBC_val is dC_val
+                            dBC_val += (2 * dout_vals[i]) * conj(x);
+                        }
+                    }
+                    const complex_t a_conj = conj(x - (!kIsVariableB ? delta_vals[i] * float(u_vals[i]) : delta_vals[i] * float(u_vals[i]) * B_vals[i]));
+                    du_vals[i] += ddelta_u * delta_vals[i];
+                    ddelta_vals[i] += ddelta_u * float(u_vals[i]) + (dx * conj(A_val) * a_conj).real_;
+                    dA_val += delta_vals[i] * dx * a_conj;
+                    if constexpr (kIsVariableB) { dB_vals[i] = dx * delta_vals[i] * float(u_vals[i]); }
+                    if constexpr (kIsVariableC) {
+                        dC_vals[i] = (2 * dout_vals[i]) * conj(!kIsVariableB ? x * B_val : x);
+                    }
+                }
+                // Block-exchange to make the atomicAdd's coalesced, otherwise they're much slower
+                if constexpr (kIsVariableB || kIsVariableC) {
+                    float dB_vals_f[kNItems * 2], dC_vals_f[kNItems * 2];
+                    if constexpr (kIsVariableB) {
+                        #pragma unroll
+                        for (int i = 0; i < kNItems; ++i) {
+                            dB_vals_f[i * 2] = dB_vals[i].real_;
+                            dB_vals_f[i * 2 + 1] = dB_vals[i].imag_;
+                        }
+                        Ktraits::BlockExchangeT(smem_exchange).BlockedToStriped(dB_vals_f, dB_vals_f);
+                    }
+                    if constexpr (kIsVariableC) {
+                        #pragma unroll
+                        for (int i = 0; i < kNItems; ++i) {
+                            dC_vals_f[i * 2] = dC_vals[i].real_;
+                            dC_vals_f[i * 2 + 1] = dC_vals[i].imag_;
+                        }
+                        auto &smem_exchange_C = !kIsVariableB ? smem_exchange : smem_exchange1;
+                        Ktraits::BlockExchangeT(smem_exchange_C).BlockedToStriped(dC_vals_f, dC_vals_f);
+                    }
+                    const int seqlen_remaining = (params.seqlen - chunk * kChunkSize) * 2 - threadIdx.x;
+                    float *dB_cur = reinterpret_cast<float *>(dB) + state_idx * params.dB_dstate_stride + chunk * kChunkSize * 2 + threadIdx.x;
+                    float *dC_cur = reinterpret_cast<float *>(dC) + state_idx * params.dC_dstate_stride + chunk * kChunkSize * 2 + threadIdx.x;
+                    #pragma unroll
+                    for (int i = 0; i < kNItems * 2; ++i) {
+                        if (i * kNThreads < seqlen_remaining) {
+                            if constexpr (kIsVariableB) { gpuAtomicAdd(dB_cur + i * kNThreads, dB_vals_f[i]); }
+                            if constexpr (kIsVariableC) { gpuAtomicAdd(dC_cur + i * kNThreads, dC_vals_f[i]); }
+                        }
+                    }
+                }
+                if constexpr (!kIsVariableB || !kIsVariableC) {
+                    float4 dA_dBC_val = make_float4(dA_val.real_, dA_val.imag_, dBC_val.real_, dBC_val.imag_);
+                    dA_dBC_val = Ktraits::BlockReduceT(smem_reduce).Sum(dA_dBC_val);
+                    dA_val = complex_t(dA_dBC_val.x, dA_dBC_val.y);
+                    dBC_val = complex_t(dA_dBC_val.z, dA_dBC_val.w);
+                    if (threadIdx.x == 0) {
+                        smem_dbc[state_idx] = chunk == params.n_chunks - 1 ? dBC_val : dBC_val + smem_dbc[state_idx];
+                    }
+                } else {
+                    dA_val = Ktraits::BlockReduceComplexT(smem_reduce_complex).Sum(dA_val);
+                }
+                if (threadIdx.x == 0) {
+                    smem_da[state_idx] = chunk == params.n_chunks - 1 ? dA_val : dA_val + smem_da[state_idx];
+                }
+            }
+        }
+
+        if constexpr (kDeltaSoftplus) {
+            __syncthreads();
+            input_t delta_vals_load[kNItems];
+            load_input<Ktraits>(delta, delta_vals_load, smem_load, params.seqlen - chunk * kChunkSize);
+            delta -= kChunkSize;
+            #pragma unroll
+            for (int i = 0; i < kNItems; ++i) {
+                float delta_val = float(delta_vals_load[i]) + delta_bias;
+                float delta_val_neg_exp = expf(-delta_val);
+                ddelta_vals[i] = delta_val <= 20.f
+                    ? ddelta_vals[i] / (1.f + delta_val_neg_exp)
+                    : ddelta_vals[i];
+            }
+        }
+        for (int i = 0; i < kNItems; ++i) { ddelta_bias_val += ddelta_vals[i]; }
+
+        input_t *du = reinterpret_cast<input_t *>(params.du_ptr) + batch_id * params.du_batch_stride
+            + dim_id * params.du_d_stride + chunk * kChunkSize;
+        input_t *ddelta = reinterpret_cast<input_t *>(params.ddelta_ptr) + batch_id * params.ddelta_batch_stride
+            + dim_id * params.ddelta_d_stride + chunk * kChunkSize;
+        __syncthreads();
+        store_output<Ktraits>(du, du_vals, smem_store, params.seqlen - chunk * kChunkSize);
+        __syncthreads();
+        store_output<Ktraits>(ddelta, ddelta_vals, smem_store, params.seqlen - chunk * kChunkSize);
+
+        Bvar -= kChunkSize * (!kIsComplex ? 1 : 2);
+        Cvar -= kChunkSize * (!kIsComplex ? 1 : 2);
+    }
+    if (params.dD_ptr != nullptr) {
+        dD_val = Ktraits::BlockReduceFloatT(smem_reduce_float).Sum(dD_val);
+        if (threadIdx.x == 0) { gpuAtomicAdd(dD, dD_val); }
+    }
+    if (params.ddelta_bias_ptr != nullptr) {
+        __syncthreads();
+        ddelta_bias_val = Ktraits::BlockReduceFloatT(smem_reduce_float).Sum(ddelta_bias_val);
+        if (threadIdx.x == 0) { gpuAtomicAdd(ddelta_bias, ddelta_bias_val); }
+    }
+    for (int state_idx = threadIdx.x; state_idx < params.dstate; state_idx += blockDim.x) {
+        gpuAtomicAdd(&(dA[state_idx * params.dA_dstate_stride]), smem_da[state_idx]);
+        weight_t dBC_val;
+        if (!kIsVariableB || !kIsVariableC) { dBC_val = smem_dbc[state_idx]; }
+        if constexpr (!kIsVariableB) {
+            gpuAtomicAdd(&(dB[state_idx * params.dB_dstate_stride]),
+                         !kIsVariableC ? dBC_val * conj(C[state_idx * params.C_dstate_stride]) : dBC_val);
+        }
+        if constexpr (!kIsVariableC) {
+            gpuAtomicAdd(&(dC[state_idx * params.dC_dstate_stride]),
+                        !kIsVariableB ? dBC_val * conj(B[state_idx * params.B_dstate_stride]) : dBC_val);
+        }
+    }
+}
+
+template<int kNThreads, int kNItems, typename input_t, typename weight_t>
+void selective_scan_bwd_launch(SSMParamsBwd &params, cudaStream_t stream) {
+    BOOL_SWITCH(params.seqlen % (kNThreads * kNItems) == 0, kIsEvenLen, [&] {
+        BOOL_SWITCH(params.is_variable_B, kIsVariableB, [&] {
+            BOOL_SWITCH(params.is_variable_C, kIsVariableC, [&] {
+                BOOL_SWITCH(params.delta_softplus, kDeltaSoftplus, [&] {
+                    BOOL_SWITCH(params.z_ptr != nullptr , kHasZ, [&] {
+                        using Ktraits = Selective_Scan_bwd_kernel_traits<kNThreads, kNItems, kIsEvenLen, kIsVariableB, kIsVariableC, kDeltaSoftplus, kHasZ, input_t, weight_t>;
+                        // using Ktraits = Selective_Scan_bwd_kernel_traits<kNThreads, kNItems, true, kIsVariableB, kIsVariableC, kDeltaSoftplus, kHasZ, input_t, weight_t>;
+                        // TODO: check this
+                        constexpr int kSmemSize = Ktraits::kSmemSize + MAX_DSTATE * sizeof(typename Ktraits::scan_t) + (kNThreads + 4 * MAX_DSTATE) * sizeof(typename Ktraits::weight_t);
+                        // printf("smem_size = %d\n", kSmemSize);
+                        dim3 grid(params.batch, params.dim);
+                        auto kernel = &selective_scan_bwd_kernel<Ktraits>;
+                        if (kSmemSize >= 48 * 1024) {
+                            C10_CUDA_CHECK(cudaFuncSetAttribute(
+                                kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
+                        }
+                        kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
+                        C10_CUDA_KERNEL_LAUNCH_CHECK();
+                    });
+                });
+            });
+        });
+    });
+}
+
+template<typename input_t, typename weight_t>
+void selective_scan_bwd_cuda(SSMParamsBwd &params, cudaStream_t stream) {
+    if (params.seqlen <= 128) {
+        selective_scan_bwd_launch<32, 4, input_t, weight_t>(params, stream);
+    } else if (params.seqlen <= 256) {
+        selective_scan_bwd_launch<32, 8, input_t, weight_t>(params, stream);
+    } else if (params.seqlen <= 512) {
+        selective_scan_bwd_launch<32, 16, input_t, weight_t>(params, stream);
+    } else if (params.seqlen <= 1024) {
+        selective_scan_bwd_launch<64, 16, input_t, weight_t>(params, stream);
+    } else {
+        selective_scan_bwd_launch<128, 16, input_t, weight_t>(params, stream);
+    }
+}

mamba/csrc/selective_scan/selective_scan_common.h

@@ -0,0 +1,221 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+#include <cuda_bf16.h>
+#include <cuda_fp16.h>
+#include <c10/util/complex.h>  // For scalar_value_type
+
+#define MAX_DSTATE 256
+
+using complex_t = c10::complex<float>;
+
+inline __device__ float2 operator+(const float2 & a, const float2 & b){
+    return {a.x + b.x, a.y + b.y};
+}
+
+inline __device__ float3 operator+(const float3 &a, const float3 &b) {
+  return {a.x + b.x, a.y + b.y, a.z + b.z};
+}
+
+inline __device__ float4 operator+(const float4 & a, const float4 & b){
+    return {a.x + b.x, a.y + b.y, a.z + b.z, a.w + b.w};
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<int BYTES> struct BytesToType {};
+
+template<> struct BytesToType<16> {
+    using Type = uint4;
+    static_assert(sizeof(Type) == 16);
+};
+
+template<> struct BytesToType<8> {
+    using Type = uint64_t;
+    static_assert(sizeof(Type) == 8);
+};
+
+template<> struct BytesToType<4> {
+    using Type = uint32_t;
+    static_assert(sizeof(Type) == 4);
+};
+
+template<> struct BytesToType<2> {
+    using Type = uint16_t;
+    static_assert(sizeof(Type) == 2);
+};
+
+template<> struct BytesToType<1> {
+    using Type = uint8_t;
+    static_assert(sizeof(Type) == 1);
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<typename scalar_t, int N>
+struct Converter{
+    static inline __device__ void to_float(const scalar_t (&src)[N], float (&dst)[N]) {
+        #pragma unroll
+        for (int i = 0; i < N; ++i) { dst[i] = src[i]; }
+    }
+};
+
+template<int N>
+struct Converter<at::Half, N>{
+    static inline __device__ void to_float(const at::Half (&src)[N], float (&dst)[N]) {
+        static_assert(N % 2 == 0);
+        auto &src2 = reinterpret_cast<const half2 (&)[N / 2]>(src);
+        auto &dst2 = reinterpret_cast<float2 (&)[N / 2]>(dst);
+        #pragma unroll
+        for (int i = 0; i < N / 2; ++i) { dst2[i] = __half22float2(src2[i]); }
+    }
+};
+
+#if __CUDA_ARCH__ >= 800
+template<int N>
+struct Converter<at::BFloat16, N>{
+    static inline __device__ void to_float(const at::BFloat16 (&src)[N], float (&dst)[N]) {
+        static_assert(N % 2 == 0);
+        auto &src2 = reinterpret_cast<const nv_bfloat162 (&)[N / 2]>(src);
+        auto &dst2 = reinterpret_cast<float2 (&)[N / 2]>(dst);
+        #pragma unroll
+        for (int i = 0; i < N / 2; ++i) { dst2[i] = __bfloat1622float2(src2[i]); }
+    }
+};
+#endif
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+// From https://stackoverflow.com/questions/9860711/cucomplex-h-and-exp
+// and https://forums.developer.nvidia.com/t/complex-number-exponential-function/24696
+__device__ __forceinline__ complex_t cexp2f(complex_t z) {
+    float t = exp2f(z.real_);
+    float c, s;
+    sincosf(z.imag_, &s, &c);
+    return complex_t(c * t, s * t);
+}
+
+__device__ __forceinline__ complex_t cexpf(complex_t z) {
+    float t = expf(z.real_);
+    float c, s;
+    sincosf(z.imag_, &s, &c);
+    return complex_t(c * t, s * t);
+}
+
+template<typename scalar_t> struct SSMScanOp;
+
+template<>
+struct SSMScanOp<float> {
+    __device__ __forceinline__ float2 operator()(const float2 &ab0, const float2 &ab1) const {
+        return make_float2(ab1.x * ab0.x, ab1.x * ab0.y + ab1.y);
+    }
+};
+
+template<>
+struct SSMScanOp<complex_t> {
+    __device__ __forceinline__ float4 operator()(const float4 &ab0, const float4 &ab1) const {
+        complex_t a0 = complex_t(ab0.x, ab0.y);
+        complex_t b0 = complex_t(ab0.z, ab0.w);
+        complex_t a1 = complex_t(ab1.x, ab1.y);
+        complex_t b1 = complex_t(ab1.z, ab1.w);
+        complex_t out_a = a1 * a0;
+        complex_t out_b = a1 * b0 + b1;
+        return make_float4(out_a.real_, out_a.imag_, out_b.real_, out_b.imag_);
+    }
+};
+
+// A stateful callback functor that maintains a running prefix to be applied
+// during consecutive scan operations.
+template <typename scalar_t> struct SSMScanPrefixCallbackOp {
+    using scan_t = std::conditional_t<std::is_same_v<scalar_t, float>, float2, float4>;
+    scan_t running_prefix;
+    // Constructor
+    __device__ SSMScanPrefixCallbackOp(scan_t running_prefix_) : running_prefix(running_prefix_) {}
+    // Callback operator to be entered by the first warp of threads in the block.
+    // Thread-0 is responsible for returning a value for seeding the block-wide scan.
+    __device__ scan_t operator()(scan_t block_aggregate) {
+        scan_t old_prefix = running_prefix;
+        running_prefix = SSMScanOp<scalar_t>()(running_prefix, block_aggregate);
+        return old_prefix;
+    }
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<typename Ktraits>
+inline __device__ void load_input(typename Ktraits::input_t *u,
+                                  typename Ktraits::input_t (&u_vals)[Ktraits::kNItems],
+                                  typename Ktraits::BlockLoadT::TempStorage &smem_load,
+                                  int seqlen) {
+    if constexpr (Ktraits::kIsEvenLen) {
+        auto& smem_load_vec = reinterpret_cast<typename Ktraits::BlockLoadVecT::TempStorage&>(smem_load);
+        using vec_t = typename Ktraits::vec_t;
+        Ktraits::BlockLoadVecT(smem_load_vec).Load(
+            reinterpret_cast<vec_t*>(u),
+            reinterpret_cast<vec_t(&)[Ktraits::kNLoads]>(u_vals)
+       );
+    } else {
+        Ktraits::BlockLoadT(smem_load).Load(u, u_vals, seqlen, 0.f);
+    }
+}
+
+template<typename Ktraits>
+inline __device__ void load_weight(typename Ktraits::input_t *Bvar,
+                                   typename Ktraits::weight_t (&B_vals)[Ktraits::kNItems],
+                                   typename Ktraits::BlockLoadWeightT::TempStorage &smem_load_weight,
+                                   int seqlen) {
+    constexpr int kNItems = Ktraits::kNItems;
+    if constexpr (!Ktraits::kIsComplex) {
+        typename Ktraits::input_t B_vals_load[kNItems];
+        if constexpr (Ktraits::kIsEvenLen) {
+            auto& smem_load_weight_vec = reinterpret_cast<typename Ktraits::BlockLoadWeightVecT::TempStorage&>(smem_load_weight);
+            using vec_t = typename Ktraits::vec_t;
+            Ktraits::BlockLoadWeightVecT(smem_load_weight_vec).Load(
+                reinterpret_cast<vec_t*>(Bvar),
+                reinterpret_cast<vec_t(&)[Ktraits::kNLoads]>(B_vals_load)
+          );
+        } else {
+            Ktraits::BlockLoadWeightT(smem_load_weight).Load(Bvar, B_vals_load, seqlen, 0.f);
+        }
+        // #pragma unroll
+        // for (int i = 0; i < kNItems; ++i) { B_vals[i] = B_vals_load[i]; }
+        Converter<typename Ktraits::input_t, kNItems>::to_float(B_vals_load, B_vals);
+    } else {
+        typename Ktraits::input_t B_vals_load[kNItems * 2];
+        if constexpr (Ktraits::kIsEvenLen) {
+            auto& smem_load_weight_vec = reinterpret_cast<typename Ktraits::BlockLoadWeightVecT::TempStorage&>(smem_load_weight);
+            using vec_t = typename Ktraits::vec_t;
+            Ktraits::BlockLoadWeightVecT(smem_load_weight_vec).Load(
+                reinterpret_cast<vec_t*>(Bvar),
+                reinterpret_cast<vec_t(&)[Ktraits::kNLoads * 2]>(B_vals_load)
+          );
+        } else {
+            Ktraits::BlockLoadWeightT(smem_load_weight).Load(Bvar, B_vals_load, seqlen, 0.f);
+        }
+        #pragma unroll
+        for (int i = 0; i < kNItems; ++i) { B_vals[i] = complex_t(B_vals_load[i * 2], B_vals_load[i * 2 + 1]); }
+    }
+}
+
+template<typename Ktraits>
+inline __device__ void store_output(typename Ktraits::input_t *out,
+                                    const float (&out_vals)[Ktraits::kNItems],
+                                    typename Ktraits::BlockStoreT::TempStorage &smem_store,
+                                    int seqlen) {
+    typename Ktraits::input_t write_vals[Ktraits::kNItems];
+    #pragma unroll
+    for (int i = 0; i < Ktraits::kNItems; ++i) { write_vals[i] = out_vals[i]; }
+    if constexpr (Ktraits::kIsEvenLen) {
+        auto& smem_store_vec = reinterpret_cast<typename Ktraits::BlockStoreVecT::TempStorage&>(smem_store);
+        using vec_t = typename Ktraits::vec_t;
+        Ktraits::BlockStoreVecT(smem_store_vec).Store(
+            reinterpret_cast<vec_t*>(out),
+            reinterpret_cast<vec_t(&)[Ktraits::kNLoads]>(write_vals)
+       );
+    } else {
+        Ktraits::BlockStoreT(smem_store).Store(out, write_vals, seqlen);
+    }
+}

mamba/csrc/selective_scan/selective_scan_fwd_bf16.cu

@@ -0,0 +1,10 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_fwd_kernel.cuh"
+
+template void selective_scan_fwd_cuda<at::BFloat16, float>(SSMParamsBase &params, cudaStream_t stream);
+template void selective_scan_fwd_cuda<at::BFloat16, complex_t>(SSMParamsBase &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_fwd_fp16.cu

@@ -0,0 +1,10 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_fwd_kernel.cuh"
+
+template void selective_scan_fwd_cuda<at::Half, float>(SSMParamsBase &params, cudaStream_t stream);
+template void selective_scan_fwd_cuda<at::Half, complex_t>(SSMParamsBase &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_fwd_fp32.cu

@@ -0,0 +1,10 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+// Split into multiple files to compile in paralell
+
+#include "selective_scan_fwd_kernel.cuh"
+
+template void selective_scan_fwd_cuda<float, float>(SSMParamsBase &params, cudaStream_t stream);
+template void selective_scan_fwd_cuda<float, complex_t>(SSMParamsBase &params, cudaStream_t stream);

mamba/csrc/selective_scan/selective_scan_fwd_kernel.cuh

@@ -0,0 +1,345 @@
+/******************************************************************************
+ * Copyright (c) 2023, Tri Dao.
+ ******************************************************************************/
+
+#pragma once
+
+#include <c10/util/BFloat16.h>
+#include <c10/util/Half.h>
+#include <c10/cuda/CUDAException.h>  // For C10_CUDA_CHECK and C10_CUDA_KERNEL_LAUNCH_CHECK
+
+#include <cub/block/block_load.cuh>
+#include <cub/block/block_store.cuh>
+#include <cub/block/block_scan.cuh>
+
+#include "selective_scan.h"
+#include "selective_scan_common.h"
+#include "static_switch.h"
+
+template<int kNThreads_, int kNItems_, int kNRows_, bool kIsEvenLen_,
+         bool kIsVariableB_, bool kIsVariableC_,
+         bool kHasZ_, typename input_t_, typename weight_t_>
+struct Selective_Scan_fwd_kernel_traits {
+    static_assert(kNItems_ % 4 == 0);
+    using input_t = input_t_;
+    using weight_t = weight_t_;
+    static constexpr int kNThreads = kNThreads_;
+    // Setting MinBlocksPerMP to be 3 (instead of 2) for 128 threads improves occupancy.
+    static constexpr int kMinBlocks = kNThreads < 128 ? 5 : 3;
+    static constexpr int kNItems = kNItems_;
+    static constexpr int kNRows = kNRows_;
+    static constexpr int kNBytes = sizeof(input_t);
+    static_assert(kNBytes == 2 || kNBytes == 4);
+    static constexpr int kNElts = kNBytes == 4 ? 4 : std::min(8, kNItems);
+    static_assert(kNItems % kNElts == 0);
+    static constexpr int kNLoads = kNItems / kNElts;
+    static constexpr bool kIsComplex = std::is_same_v<weight_t, complex_t>;
+    static constexpr bool kIsEvenLen = kIsEvenLen_;
+    static constexpr bool kIsVariableB = kIsVariableB_;
+    static constexpr bool kIsVariableC = kIsVariableC_;
+    static constexpr bool kHasZ = kHasZ_;
+
+    static constexpr bool kDirectIO = kIsEvenLen && kNLoads == 1;
+
+    using vec_t = typename BytesToType<kNBytes * kNElts>::Type;
+    using scan_t = std::conditional_t<!kIsComplex, float2, float4>;
+    using BlockLoadT = cub::BlockLoad<input_t, kNThreads, kNItems, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadVecT = cub::BlockLoad<vec_t, kNThreads, kNLoads,
+        !kDirectIO ? cub::BLOCK_LOAD_WARP_TRANSPOSE : cub::BLOCK_LOAD_DIRECT>;
+    using BlockLoadWeightT = cub::BlockLoad<input_t, kNThreads, !kIsComplex ? kNItems : kNItems * 2, cub::BLOCK_LOAD_WARP_TRANSPOSE>;
+    using BlockLoadWeightVecT = cub::BlockLoad<vec_t, kNThreads, !kIsComplex ? kNLoads : kNLoads * 2,
+        !kDirectIO ? cub::BLOCK_LOAD_WARP_TRANSPOSE  : cub::BLOCK_LOAD_DIRECT>;
+    using BlockStoreT = cub::BlockStore<input_t, kNThreads, kNItems, cub::BLOCK_STORE_WARP_TRANSPOSE>;
+    using BlockStoreVecT = cub::BlockStore<vec_t, kNThreads, kNLoads,
+        !kDirectIO ? cub::BLOCK_STORE_WARP_TRANSPOSE : cub::BLOCK_STORE_DIRECT>;
+    // using BlockScanT = cub::BlockScan<scan_t, kNThreads, cub::BLOCK_SCAN_RAKING_MEMOIZE>;
+    // using BlockScanT = cub::BlockScan<scan_t, kNThreads, cub::BLOCK_SCAN_RAKING>;
+    using BlockScanT = cub::BlockScan<scan_t, kNThreads, cub::BLOCK_SCAN_WARP_SCANS>;
+    static constexpr int kSmemIOSize = std::max({sizeof(typename BlockLoadT::TempStorage),
+                                                 sizeof(typename BlockLoadVecT::TempStorage),
+                                                 (int(kIsVariableB) + int(kIsVariableC)) * sizeof(typename BlockLoadWeightT::TempStorage),
+                                                 (int(kIsVariableB) + int(kIsVariableC)) * sizeof(typename BlockLoadWeightVecT::TempStorage),
+                                                 sizeof(typename BlockStoreT::TempStorage),
+                                                 sizeof(typename BlockStoreVecT::TempStorage)});
+    static constexpr int kSmemSize = kSmemIOSize + sizeof(typename BlockScanT::TempStorage);
+};
+
+template<typename Ktraits>
+__global__ __launch_bounds__(Ktraits::kNThreads, Ktraits::kMinBlocks)
+void selective_scan_fwd_kernel(SSMParamsBase params) {
+    constexpr bool kIsComplex = Ktraits::kIsComplex;
+    constexpr bool kIsVariableB = Ktraits::kIsVariableB;
+    constexpr bool kIsVariableC = Ktraits::kIsVariableC;
+    constexpr bool kHasZ = Ktraits::kHasZ;
+    constexpr int kNThreads = Ktraits::kNThreads;
+    constexpr int kNItems = Ktraits::kNItems;
+    constexpr int kNRows = Ktraits::kNRows;
+    constexpr bool kDirectIO = Ktraits::kDirectIO;
+    using input_t = typename Ktraits::input_t;
+    using weight_t = typename Ktraits::weight_t;
+    using scan_t = typename Ktraits::scan_t;
+
+    // Shared memory.
+    extern __shared__ char smem_[];
+    // cast to lvalue reference of expected type
+    // char *smem_loadstorescan = smem_ + 2 * MAX_DSTATE * sizeof(weight_t);
+    // auto& smem_load = reinterpret_cast<typename BlockLoadT::TempStorage&>(smem_ + 2 * MAX_DSTATE * sizeof(weight_t));
+    // auto& smem_load = reinterpret_cast<typename BlockLoadT::TempStorage&>(smem_loadstorescan);
+    auto& smem_load = reinterpret_cast<typename Ktraits::BlockLoadT::TempStorage&>(smem_);
+    auto& smem_load_weight = reinterpret_cast<typename Ktraits::BlockLoadWeightT::TempStorage&>(smem_);
+    auto& smem_load_weight1 = *reinterpret_cast<typename Ktraits::BlockLoadWeightT::TempStorage*>(smem_ + sizeof(typename Ktraits::BlockLoadWeightT::TempStorage));
+    auto& smem_store = reinterpret_cast<typename Ktraits::BlockStoreT::TempStorage&>(smem_);
+    auto& smem_scan = *reinterpret_cast<typename Ktraits::BlockScanT::TempStorage*>(smem_ + Ktraits::kSmemIOSize);
+    // weight_t *smem_a = reinterpret_cast<weight_t *>(smem_ + smem_loadstorescan_size);
+    // weight_t *smem_bc = reinterpret_cast<weight_t *>(smem_a + MAX_DSTATE);
+    scan_t *smem_running_prefix = reinterpret_cast<scan_t *>(smem_ + Ktraits::kSmemSize);
+
+    const int batch_id = blockIdx.x;
+    const int dim_id = blockIdx.y;
+    const int group_id = dim_id / (params.dim_ngroups_ratio);
+    input_t *u = reinterpret_cast<input_t *>(params.u_ptr) + batch_id * params.u_batch_stride
+        + dim_id * kNRows * params.u_d_stride;
+    input_t *delta = reinterpret_cast<input_t *>(params.delta_ptr) + batch_id * params.delta_batch_stride
+        + dim_id * kNRows * params.delta_d_stride;
+    weight_t *A = reinterpret_cast<weight_t *>(params.A_ptr) + dim_id * kNRows * params.A_d_stride;
+    weight_t *B = reinterpret_cast<weight_t *>(params.B_ptr) + dim_id * kNRows * params.B_d_stride;
+    input_t *Bvar = reinterpret_cast<input_t *>(params.B_ptr) + batch_id * params.B_batch_stride + group_id * params.B_group_stride;
+    weight_t *C = reinterpret_cast<weight_t *>(params.C_ptr) + dim_id * kNRows * params.C_d_stride;
+    input_t *Cvar = reinterpret_cast<input_t *>(params.C_ptr) + batch_id * params.C_batch_stride + group_id * params.C_group_stride;
+    scan_t *x = reinterpret_cast<scan_t *>(params.x_ptr) + (batch_id * params.dim + dim_id * kNRows) * params.n_chunks * params.dstate;
+
+    float D_val[kNRows] = {0};
+    if (params.D_ptr != nullptr) {
+        #pragma unroll
+        for (int r = 0; r < kNRows; ++r) {
+            D_val[r] = reinterpret_cast<float *>(params.D_ptr)[dim_id * kNRows + r];
+        }
+    }
+    float delta_bias[kNRows] = {0};
+    if (params.delta_bias_ptr != nullptr) {
+        #pragma unroll
+        for (int r = 0; r < kNRows; ++r) {
+            delta_bias[r] = reinterpret_cast<float *>(params.delta_bias_ptr)[dim_id * kNRows + r];
+        }
+    }
+
+    // for (int state_idx = threadIdx.x; state_idx < params.dstate; state_idx += blockDim.x) {
+    //     smem_a[state_idx] = A[state_idx * params.A_dstate_stride];
+    //     smem_bc[state_idx] = B[state_idx * params.B_dstate_stride] * C[state_idx * params.C_dstate_stride];
+    // }
+
+    constexpr int kChunkSize = kNThreads * kNItems;
+    for (int chunk = 0; chunk < params.n_chunks; ++chunk) {
+        input_t u_vals[kNRows][kNItems], delta_vals_load[kNRows][kNItems];
+        __syncthreads();
+        #pragma unroll
+        for (int r = 0; r < kNRows; ++r) {
+            if constexpr (!kDirectIO) {
+                if (r > 0) { __syncthreads(); }
+            }
+            load_input<Ktraits>(u + r * params.u_d_stride, u_vals[r], smem_load, params.seqlen - chunk * kChunkSize);
+            if constexpr (!kDirectIO) { __syncthreads(); }
+            load_input<Ktraits>(delta + r * params.delta_d_stride, delta_vals_load[r], smem_load, params.seqlen - chunk * kChunkSize);
+        }
+        u += kChunkSize;
+        delta += kChunkSize;
+
+        float delta_vals[kNRows][kNItems], delta_u_vals[kNRows][kNItems], out_vals[kNRows][kNItems];
+        #pragma unroll
+        for (int r = 0; r < kNRows; ++r) {
+            #pragma unroll
+            for (int i = 0; i < kNItems; ++i) {
+                float u_val = float(u_vals[r][i]);
+                delta_vals[r][i] = float(delta_vals_load[r][i]) + delta_bias[r];
+                if (params.delta_softplus) {
+                    delta_vals[r][i] = delta_vals[r][i] <= 20.f ? log1pf(expf(delta_vals[r][i])) : delta_vals[r][i];
+                }
+                delta_u_vals[r][i] = delta_vals[r][i] * u_val;
+                out_vals[r][i] = D_val[r] * u_val;
+            }
+        }
+
+        __syncthreads();
+        for (int state_idx = 0; state_idx < params.dstate; ++state_idx) {
+            weight_t A_val[kNRows];
+            #pragma unroll
+            for (int r = 0; r < kNRows; ++r) {
+                A_val[r] = A[state_idx * params.A_dstate_stride + r * params.A_d_stride];
+                // Multiply the real part of A with LOG2E so we can use exp2f instead of expf.
+                constexpr float kLog2e = M_LOG2E;
+                if constexpr (!kIsComplex) {
+                    A_val[r] *= kLog2e;
+                } else {
+                    A_val[r].real_ *= kLog2e;
+                }
+            }
+            // This variable holds B * C if both B and C are constant across seqlen. If only B varies
+            // across seqlen, this holds C. If only C varies across seqlen, this holds B.
+            // If both B and C vary, this is unused.
+            weight_t BC_val[kNRows];
+            weight_t B_vals[kNItems], C_vals[kNItems];
+            if constexpr (kIsVariableB) {
+                load_weight<Ktraits>(Bvar + state_idx * params.B_dstate_stride, B_vals,
+                    smem_load_weight, (params.seqlen - chunk * kChunkSize) * (!kIsComplex ? 1 : 2));
+                if constexpr (!kIsVariableC) {
+                    #pragma unroll
+                    for (int r = 0; r < kNRows; ++r) {
+                        BC_val[r] = C[state_idx * params.C_dstate_stride + r * params.C_d_stride];
+                    }
+                }
+            }
+            if constexpr (kIsVariableC) {
+                auto &smem_load_weight_C = !kIsVariableB ? smem_load_weight : smem_load_weight1;
+                load_weight<Ktraits>(Cvar + state_idx * params.C_dstate_stride, C_vals,
+                    smem_load_weight_C, (params.seqlen - chunk * kChunkSize) * (!kIsComplex ? 1 : 2));
+                if constexpr (!kIsVariableB) {
+                    #pragma unroll
+                    for (int r = 0; r < kNRows; ++r) {
+                        BC_val[r] = B[state_idx * params.B_dstate_stride + r * params.B_d_stride];
+                    }
+                }
+            }
+            if constexpr (!kIsVariableB && !kIsVariableC) {
+                #pragma unroll
+                for (int r = 0; r < kNRows; ++r) {
+                    BC_val[r] = B[state_idx * params.B_dstate_stride + r * params.B_d_stride] * C[state_idx * params.C_dstate_stride + r * params.C_d_stride];
+                }
+            }
+
+            #pragma unroll
+            for (int r = 0; r < kNRows; ++r) {
+                if (r > 0) { __syncthreads(); }  // Scan could be using the same smem
+                scan_t thread_data[kNItems];
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    if constexpr (!kIsComplex) {
+                        thread_data[i] = make_float2(exp2f(delta_vals[r][i] * A_val[r]),
+                                                     !kIsVariableB ? delta_u_vals[r][i] : B_vals[i] * delta_u_vals[r][i]);
+                        if constexpr (!Ktraits::kIsEvenLen) {  // So that the last state is correct
+                            if (threadIdx.x * kNItems + i >= params.seqlen - chunk * kChunkSize) {
+                                thread_data[i] = make_float2(1.f, 0.f);
+                            }
+                        }
+                    } else {
+                        // Pytorch's implementation of complex exp (which calls thrust) is very slow
+                        complex_t delta_a_exp = cexp2f(delta_vals[r][i] * A_val[r]);
+                        weight_t B_delta_u_val = !kIsVariableB ? delta_u_vals[r][i] : B_vals[i] * delta_u_vals[r][i];
+                        thread_data[i] = make_float4(delta_a_exp.real_, delta_a_exp.imag_, B_delta_u_val.real_, B_delta_u_val.imag_);
+                        if constexpr (!Ktraits::kIsEvenLen) {  // So that the last state is correct
+                            if (threadIdx.x * kNItems + i >= params.seqlen - chunk * kChunkSize) {
+                                thread_data[i] = make_float4(1.f, 0.f, 0.f, 0.f);
+                            }
+                        }
+                    }
+                }
+                // Initialize running total
+                scan_t running_prefix;
+                if constexpr (!kIsComplex) {
+                    // If we use WARP_SCAN then all lane 0 of all warps (not just thread 0) needs to read
+                    running_prefix = chunk > 0 && threadIdx.x % 32 == 0 ? smem_running_prefix[state_idx + r * MAX_DSTATE] : make_float2(1.f, 0.f);
+                    // running_prefix = chunk > 0 && threadIdx.x == 0 ? smem_running_prefix[state_idx] : make_float2(1.f, 0.f);
+                } else {
+                    running_prefix = chunk > 0 && threadIdx.x % 32 == 0 ? smem_running_prefix[state_idx + r * MAX_DSTATE] : make_float4(1.f, 0.f, 0.f, 0.f);
+                    // running_prefix = chunk > 0 && threadIdx.x == 0 ? smem_running_prefix[state_idx] : make_float4(1.f, 0.f, 0.f, 0.f);
+                }
+                SSMScanPrefixCallbackOp<weight_t> prefix_op(running_prefix);
+                Ktraits::BlockScanT(smem_scan).InclusiveScan(
+                    thread_data, thread_data, SSMScanOp<weight_t>(), prefix_op
+                );
+                // There's a syncthreads in the scan op, so we don't need to sync here.
+                // Unless there's only 1 warp, but then it's the same thread (0) reading and writing.
+                if (threadIdx.x == 0) {
+                    smem_running_prefix[state_idx] = prefix_op.running_prefix;
+                    x[(r * params.n_chunks + chunk) * params.dstate + state_idx] = prefix_op.running_prefix;
+                }
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    const weight_t C_val = !kIsVariableC
+                        ? BC_val[r]
+                        : (!kIsVariableB ? BC_val[r] * C_vals[i] : C_vals[i]);
+                    if constexpr (!kIsComplex) {
+                        out_vals[r][i] += thread_data[i].y * C_val;
+                    } else {
+                        out_vals[r][i] += (complex_t(thread_data[i].z, thread_data[i].w) * C_val).real_ * 2;
+                    }
+                }
+            }
+        }
+
+        input_t *out = reinterpret_cast<input_t *>(params.out_ptr) + batch_id * params.out_batch_stride
+            + dim_id * kNRows * params.out_d_stride + chunk * kChunkSize;
+        __syncthreads();
+        #pragma unroll
+        for (int r = 0; r < kNRows; ++r) {
+            if constexpr (!kDirectIO) {
+                if (r > 0) { __syncthreads(); }
+            }
+            store_output<Ktraits>(out + r * params.out_d_stride, out_vals[r], smem_store, params.seqlen - chunk * kChunkSize);
+        }
+
+        if constexpr (kHasZ) {
+            input_t *z = reinterpret_cast<input_t *>(params.z_ptr) + batch_id * params.z_batch_stride
+                + dim_id * kNRows * params.z_d_stride + chunk * kChunkSize;
+            input_t *out_z = reinterpret_cast<input_t *>(params.out_z_ptr) + batch_id * params.out_z_batch_stride
+                + dim_id * kNRows * params.out_z_d_stride + chunk * kChunkSize;
+            #pragma unroll
+            for (int r = 0; r < kNRows; ++r) {
+                input_t z_vals[kNItems];
+                __syncthreads();
+                load_input<Ktraits>(z + r * params.z_d_stride, z_vals, smem_load, params.seqlen - chunk * kChunkSize);
+                #pragma unroll
+                for (int i = 0; i < kNItems; ++i) {
+                    float z_val = z_vals[i];
+                    out_vals[r][i] *= z_val / (1 + expf(-z_val));
+                }
+                __syncthreads();
+                store_output<Ktraits>(out_z + r * params.out_z_d_stride, out_vals[r], smem_store, params.seqlen - chunk * kChunkSize);
+            }
+        }
+
+        Bvar += kChunkSize * (!kIsComplex ? 1 : 2);
+        Cvar += kChunkSize * (!kIsComplex ? 1 : 2);
+    }
+}
+
+template<int kNThreads, int kNItems, typename input_t, typename weight_t>
+void selective_scan_fwd_launch(SSMParamsBase &params, cudaStream_t stream) {
+    // Only kNRows == 1 is tested for now, which ofc doesn't differ from previously when we had each block
+    // processing 1 row.
+    constexpr int kNRows = 1;
+    BOOL_SWITCH(params.seqlen % (kNThreads * kNItems) == 0, kIsEvenLen, [&] {
+        BOOL_SWITCH(params.is_variable_B, kIsVariableB, [&] {
+            BOOL_SWITCH(params.is_variable_C, kIsVariableC, [&] {
+                BOOL_SWITCH(params.z_ptr != nullptr , kHasZ, [&] {
+                    using Ktraits = Selective_Scan_fwd_kernel_traits<kNThreads, kNItems, kNRows, kIsEvenLen, kIsVariableB, kIsVariableC, kHasZ, input_t, weight_t>;
+                    // constexpr int kSmemSize = Ktraits::kSmemSize;
+                    constexpr int kSmemSize = Ktraits::kSmemSize + kNRows * MAX_DSTATE * sizeof(typename Ktraits::scan_t);
+                    // printf("smem_size = %d\n", kSmemSize);
+                    dim3 grid(params.batch, params.dim / kNRows);
+                    auto kernel = &selective_scan_fwd_kernel<Ktraits>;
+                    if (kSmemSize >= 48 * 1024) {
+                        C10_CUDA_CHECK(cudaFuncSetAttribute(
+                            kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, kSmemSize));
+                    }
+                    kernel<<<grid, Ktraits::kNThreads, kSmemSize, stream>>>(params);
+                    C10_CUDA_KERNEL_LAUNCH_CHECK();
+                });
+            });
+        });
+    });
+}
+
+template<typename input_t, typename weight_t>
+void selective_scan_fwd_cuda(SSMParamsBase &params, cudaStream_t stream) {
+    if (params.seqlen <= 128) {
+        selective_scan_fwd_launch<32, 4, input_t, weight_t>(params, stream);
+    } else if (params.seqlen <= 256) {
+        selective_scan_fwd_launch<32, 8, input_t, weight_t>(params, stream);
+    } else if (params.seqlen <= 512) {
+        selective_scan_fwd_launch<32, 16, input_t, weight_t>(params, stream);
+    } else if (params.seqlen <= 1024) {
+        selective_scan_fwd_launch<64, 16, input_t, weight_t>(params, stream);
+    } else {
+        selective_scan_fwd_launch<128, 16, input_t, weight_t>(params, stream);
+    }
+}

mamba/csrc/selective_scan/static_switch.h

@@ -0,0 +1,25 @@
+// Inspired by https://github.com/NVIDIA/DALI/blob/main/include/dali/core/static_switch.h
+// and https://github.com/pytorch/pytorch/blob/master/aten/src/ATen/Dispatch.h
+
+#pragma once
+
+/// @param COND       - a boolean expression to switch by
+/// @param CONST_NAME - a name given for the constexpr bool variable.
+/// @param ...       - code to execute for true and false
+///
+/// Usage:
+/// ```
+/// BOOL_SWITCH(flag, BoolConst, [&] {
+///     some_function<BoolConst>(...);
+/// });
+/// ```
+#define BOOL_SWITCH(COND, CONST_NAME, ...)                                           \
+    [&] {                                                                            \
+        if (COND) {                                                                  \
+            constexpr bool CONST_NAME = true;                                        \
+            return __VA_ARGS__();                                                    \
+        } else {                                                                     \
+            constexpr bool CONST_NAME = false;                                       \
+            return __VA_ARGS__();                                                    \
+        }                                                                            \
+    }()

mamba/csrc/selective_scan/uninitialized_copy.cuh

@@ -0,0 +1,69 @@
+/******************************************************************************
+ * Copyright (c) 2011-2022, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the NVIDIA CORPORATION nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ ******************************************************************************/
+
+#pragma once
+
+#include <cub/config.cuh>
+
+#include <cuda/std/type_traits>
+
+
+namespace detail
+{
+
+#if defined(_NVHPC_CUDA)
+template <typename T, typename U>
+__host__ __device__ void uninitialized_copy(T *ptr, U &&val)
+{
+  // NVBug 3384810
+  new (ptr) T(::cuda::std::forward<U>(val));
+}
+#else
+template <typename T,
+          typename U,
+          typename ::cuda::std::enable_if<
+            ::cuda::std::is_trivially_copyable<T>::value,
+            int
+          >::type = 0>
+__host__ __device__ void uninitialized_copy(T *ptr, U &&val)
+{
+  *ptr = ::cuda::std::forward<U>(val);
+}
+
+template <typename T,
+         typename U,
+         typename ::cuda::std::enable_if<
+           !::cuda::std::is_trivially_copyable<T>::value,
+           int
+         >::type = 0>
+__host__ __device__ void uninitialized_copy(T *ptr, U &&val)
+{
+  new (ptr) T(::cuda::std::forward<U>(val));
+}
+#endif
+
+} // namespace detail

mamba/evals/lm_harness_eval.py

@@ -0,0 +1,39 @@
+import torch
+
+import transformers
+from transformers import AutoTokenizer
+
+from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel
+
+from lm_eval.api.model import LM
+from lm_eval.models.huggingface import HFLM
+from lm_eval.api.registry import register_model
+from lm_eval.__main__ import cli_evaluate
+
+
+@register_model("mamba")
+class MambaEvalWrapper(HFLM):
+
+    AUTO_MODEL_CLASS = transformers.AutoModelForCausalLM
+
+    def __init__(self, pretrained="state-spaces/mamba-2.8b", max_length=2048, batch_size=None, device="cuda",
+                 dtype=torch.float16):
+        LM.__init__(self)
+        self._model = MambaLMHeadModel.from_pretrained(pretrained, device=device, dtype=dtype)
+        self.tokenizer = AutoTokenizer.from_pretrained("EleutherAI/gpt-neox-20b")
+        self.tokenizer.pad_token_id = self.tokenizer.eos_token_id
+        self.vocab_size = self.tokenizer.vocab_size
+        self._batch_size = batch_size if batch_size is None else 64
+        self._max_length = max_length
+        self._device = torch.device(device)
+
+    @property
+    def batch_size(self):
+        return self._batch_size
+
+    def _model_generate(self, context, max_length, stop, **generation_kwargs):
+        raise NotImplementedError()
+
+
+if __name__ == "__main__":
+    cli_evaluate()

mamba/mamba_ssm/__init__.py

@@ -0,0 +1,5 @@
+__version__ = "1.0.1"
+
+from mamba_ssm.ops.selective_scan_interface import selective_scan_fn, mamba_inner_fn, bimamba_inner_fn
+from mamba_ssm.modules.mamba_simple import Mamba
+from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel

mamba/mamba_ssm/models/mixer_seq_simple.py

@@ -0,0 +1,233 @@
+# Copyright (c) 2023, Albert Gu, Tri Dao.
+
+import math
+from functools import partial
+
+from collections import namedtuple
+
+import torch
+import torch.nn as nn
+
+from mamba_ssm.modules.mamba_simple import Mamba, Block
+from mamba_ssm.utils.generation import GenerationMixin
+from mamba_ssm.utils.hf import load_config_hf, load_state_dict_hf
+
+try:
+    from mamba_ssm.ops.triton.layernorm import RMSNorm, layer_norm_fn, rms_norm_fn
+except ImportError:
+    RMSNorm, layer_norm_fn, rms_norm_fn = None, None, None
+
+
+def create_block(
+    d_model,
+    ssm_cfg=None,
+    norm_epsilon=1e-5,
+    rms_norm=False,
+    residual_in_fp32=False,
+    fused_add_norm=False,
+    layer_idx=None,
+    device=None,
+    dtype=None,
+):
+    if ssm_cfg is None:
+        ssm_cfg = {}
+    factory_kwargs = {"device": device, "dtype": dtype}
+    mixer_cls = partial(Mamba, layer_idx=layer_idx, **ssm_cfg, **factory_kwargs)
+    norm_cls = partial(
+        nn.LayerNorm if not rms_norm else RMSNorm, eps=norm_epsilon, **factory_kwargs
+    )
+    block = Block(
+        d_model,
+        mixer_cls,
+        norm_cls=norm_cls,
+        fused_add_norm=fused_add_norm,
+        residual_in_fp32=residual_in_fp32,
+    )
+    block.layer_idx = layer_idx
+    return block
+
+
+# https://github.com/huggingface/transformers/blob/c28d04e9e252a1a099944e325685f14d242ecdcd/src/transformers/models/gpt2/modeling_gpt2.py#L454
+def _init_weights(
+    module,
+    n_layer,
+    initializer_range=0.02,  # Now only used for embedding layer.
+    rescale_prenorm_residual=True,
+    n_residuals_per_layer=1,  # Change to 2 if we have MLP
+):
+    if isinstance(module, nn.Linear):
+        if module.bias is not None:
+            if not getattr(module.bias, "_no_reinit", False):
+                nn.init.zeros_(module.bias)
+    elif isinstance(module, nn.Embedding):
+        nn.init.normal_(module.weight, std=initializer_range)
+
+    if rescale_prenorm_residual:
+        # Reinitialize selected weights subject to the OpenAI GPT-2 Paper Scheme:
+        #   > A modified initialization which accounts for the accumulation on the residual path with model depth. Scale
+        #   > the weights of residual layers at initialization by a factor of 1/√N where N is the # of residual layers.
+        #   >   -- GPT-2 :: https://openai.com/blog/better-language-models/
+        #
+        # Reference (Megatron-LM): https://github.com/NVIDIA/Megatron-LM/blob/main/megatron/model/gpt_model.py
+        for name, p in module.named_parameters():
+            if name in ["out_proj.weight", "fc2.weight"]:
+                # Special Scaled Initialization --> There are 2 Layer Norms per Transformer Block
+                # Following Pytorch init, except scale by 1/sqrt(2 * n_layer)
+                # We need to reinit p since this code could be called multiple times
+                # Having just p *= scale would repeatedly scale it down
+                nn.init.kaiming_uniform_(p, a=math.sqrt(5))
+                with torch.no_grad():
+                    p /= math.sqrt(n_residuals_per_layer * n_layer)
+
+
+class MixerModel(nn.Module):
+    def __init__(
+        self,
+        d_model: int,
+        n_layer: int,
+        vocab_size: int,
+        ssm_cfg=None,
+        norm_epsilon: float = 1e-5,
+        rms_norm: bool = False,
+        initializer_cfg=None,
+        fused_add_norm=False,
+        residual_in_fp32=False,
+        device=None,
+        dtype=None,
+    ) -> None:
+        factory_kwargs = {"device": device, "dtype": dtype}
+        super().__init__()
+        self.residual_in_fp32 = residual_in_fp32
+
+        self.embedding = nn.Embedding(vocab_size, d_model, **factory_kwargs)
+
+        # We change the order of residual and layer norm:
+        # Instead of LN -> Attn / MLP -> Add, we do:
+        # Add -> LN -> Attn / MLP / Mixer, returning both the residual branch (output of Add) and
+        # the main branch (output of MLP / Mixer). The model definition is unchanged.
+        # This is for performance reason: we can fuse add + layer_norm.
+        self.fused_add_norm = fused_add_norm
+        if self.fused_add_norm:
+            if layer_norm_fn is None or rms_norm_fn is None:
+                raise ImportError("Failed to import Triton LayerNorm / RMSNorm kernels")
+
+        self.layers = nn.ModuleList(
+            [
+                create_block(
+                    d_model,
+                    ssm_cfg=ssm_cfg,
+                    norm_epsilon=norm_epsilon,
+                    rms_norm=rms_norm,
+                    residual_in_fp32=residual_in_fp32,
+                    fused_add_norm=fused_add_norm,
+                    layer_idx=i,
+                    **factory_kwargs,
+                )
+                for i in range(n_layer)
+            ]
+        )
+
+        self.norm_f = (nn.LayerNorm if not rms_norm else RMSNorm)(
+            d_model, eps=norm_epsilon, **factory_kwargs
+        )
+
+        self.apply(
+            partial(
+                _init_weights,
+                n_layer=n_layer,
+                **(initializer_cfg if initializer_cfg is not None else {}),
+            )
+        )
+
+    def allocate_inference_cache(self, batch_size, max_seqlen, dtype=None, **kwargs):
+        return {
+            i: layer.allocate_inference_cache(batch_size, max_seqlen, dtype=dtype, **kwargs)
+            for i, layer in enumerate(self.layers)
+        }
+
+    def forward(self, input_ids, inference_params=None):
+        hidden_states = self.embedding(input_ids)
+        residual = None
+        for layer in self.layers:
+            hidden_states, residual = layer(
+                hidden_states, residual, inference_params=inference_params
+            )
+        if not self.fused_add_norm:
+            residual = (hidden_states + residual) if residual is not None else hidden_states
+            hidden_states = self.norm_f(residual.to(dtype=self.norm_f.weight.dtype))
+        else:
+            # Set prenorm=False here since we don't need the residual
+            fused_add_norm_fn = rms_norm_fn if isinstance(self.norm_f, RMSNorm) else layer_norm_fn
+            hidden_states = fused_add_norm_fn(
+                hidden_states,
+                self.norm_f.weight,
+                self.norm_f.bias,
+                eps=self.norm_f.eps,
+                residual=residual,
+                prenorm=False,
+                residual_in_fp32=self.residual_in_fp32,
+            )
+        return hidden_states
+
+
+class MambaLMHeadModel(nn.Module, GenerationMixin):
+
+    def __init__(
+        self,
+        d_model: int,
+        n_layer: int,
+        vocab_size: int,
+        initializer_cfg=None,
+        pad_vocab_size_multiple: int = 1,
+        device=None,
+        dtype=None,
+        **backbone_kwargs,
+    ) -> None:
+        factory_kwargs = {"device": device, "dtype": dtype}
+        super().__init__()
+        if vocab_size % pad_vocab_size_multiple != 0:
+            vocab_size += pad_vocab_size_multiple - (vocab_size % pad_vocab_size_multiple)
+        self.backbone = MixerModel(
+            d_model=d_model,
+            n_layer=n_layer,
+            vocab_size=vocab_size,
+            initializer_cfg=initializer_cfg,
+            **backbone_kwargs,
+            **factory_kwargs,
+        )
+        self.lm_head = nn.Linear(d_model, vocab_size, bias=False, **factory_kwargs)
+
+        # Initialize weights and apply final processing
+        self.apply(
+            partial(
+                _init_weights,
+                n_layer=n_layer,
+                **(initializer_cfg if initializer_cfg is not None else {}),
+            )
+        )
+        self.tie_weights()
+
+    def tie_weights(self):
+        self.lm_head.weight = self.backbone.embedding.weight
+
+    def allocate_inference_cache(self, batch_size, max_seqlen, dtype=None, **kwargs):
+        return self.backbone.allocate_inference_cache(batch_size, max_seqlen, dtype=dtype, **kwargs)
+
+    def forward(self, input_ids, position_ids=None, inference_params=None, num_last_tokens=0):
+        """
+        "position_ids" is just to be compatible with Transformer generation. We don't use it.
+        num_last_tokens: if > 0, only return the logits for the last n tokens
+        """
+        hidden_states = self.backbone(input_ids, inference_params=inference_params)
+        if num_last_tokens > 0:
+            hidden_states = hidden_states[:, -num_last_tokens:]
+        lm_logits = self.lm_head(hidden_states)
+        CausalLMOutput = namedtuple("CausalLMOutput", ["logits"])
+        return CausalLMOutput(logits=lm_logits)
+
+    @classmethod
+    def from_pretrained(cls, pretrained_model_name, device=None, dtype=None, **kwargs):
+        config = load_config_hf(pretrained_model_name)
+        model = cls(**config, device=device, dtype=dtype, **kwargs)
+        model.load_state_dict(load_state_dict_hf(pretrained_model_name, device=device, dtype=dtype))
+        return model

mamba/mamba_ssm/modules/mamba_simple.py

@@ -0,0 +1,418 @@
+# Copyright (c) 2023, Tri Dao, Albert Gu.
+
+import math
+from typing import Optional
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch import Tensor
+
+from einops import rearrange, repeat
+
+try:
+    from causal_conv1d import causal_conv1d_fn, causal_conv1d_update
+except ImportError:
+    causal_conv1d_fn, causal_conv1d_update = None
+
+try:
+    from mamba_ssm.ops.selective_scan_interface import selective_scan_fn, mamba_inner_fn, bimamba_inner_fn, mamba_inner_fn_no_out_proj
+except ImportError:
+    selective_scan_fn, mamba_inner_fn, bimamba_inner_fn, mamba_inner_fn_no_out_proj = None, None, None, None, None
+
+try:
+    from mamba_ssm.ops.triton.selective_state_update import selective_state_update
+except ImportError:
+    selective_state_update = None
+
+try:
+    from mamba_ssm.ops.triton.layernorm import RMSNorm, layer_norm_fn, rms_norm_fn
+except ImportError:
+    RMSNorm, layer_norm_fn, rms_norm_fn = None, None, None
+
+
+class Mamba(nn.Module):
+    def __init__(
+        self,
+        d_model,
+        d_state=16,
+        d_conv=4,
+        expand=2,
+        dt_rank="auto",
+        dt_min=0.001,
+        dt_max=0.1,
+        dt_init="random",
+        dt_scale=1.0,
+        dt_init_floor=1e-4,
+        conv_bias=True,
+        bias=False,
+        use_fast_path=True,  # Fused kernel options
+        layer_idx=None,
+        device=None,
+        dtype=None,
+        bimamba=True,
+    ):
+        factory_kwargs = {"device": device, "dtype": dtype}
+        super().__init__()
+        self.d_model = d_model
+        self.d_state = d_state
+        self.d_conv = d_conv
+        self.expand = expand
+        self.d_inner = int(self.expand * self.d_model)
+        self.dt_rank = math.ceil(self.d_model / 16) if dt_rank == "auto" else dt_rank
+        self.use_fast_path = use_fast_path
+        self.layer_idx = layer_idx
+        self.bimamba = bimamba
+
+        self.in_proj = nn.Linear(self.d_model, self.d_inner * 2, bias=bias, **factory_kwargs)
+
+        self.conv1d = nn.Conv1d(
+            in_channels=self.d_inner,
+            out_channels=self.d_inner,
+            bias=conv_bias,
+            kernel_size=d_conv,
+            groups=self.d_inner,
+            padding=d_conv - 1,
+            **factory_kwargs,
+        )
+
+        self.activation = "silu"
+        self.act = nn.SiLU()
+
+        self.x_proj = nn.Linear(
+            self.d_inner, self.dt_rank + self.d_state * 2, bias=False, **factory_kwargs
+        )
+        self.dt_proj = nn.Linear(self.dt_rank, self.d_inner, bias=True, **factory_kwargs)
+
+        # Initialize special dt projection to preserve variance at initialization
+        dt_init_std = self.dt_rank**-0.5 * dt_scale
+        if dt_init == "constant":
+            nn.init.constant_(self.dt_proj.weight, dt_init_std)
+        elif dt_init == "random":
+            nn.init.uniform_(self.dt_proj.weight, -dt_init_std, dt_init_std)
+        else:
+            raise NotImplementedError
+
+        # Initialize dt bias so that F.softplus(dt_bias) is between dt_min and dt_max
+        dt = torch.exp(
+            torch.rand(self.d_inner, **factory_kwargs) * (math.log(dt_max) - math.log(dt_min))
+            + math.log(dt_min)
+        ).clamp(min=dt_init_floor)
+        # Inverse of softplus: https://github.com/pytorch/pytorch/issues/72759
+        inv_dt = dt + torch.log(-torch.expm1(-dt))
+        with torch.no_grad():
+            self.dt_proj.bias.copy_(inv_dt)
+        # Our initialization would set all Linear.bias to zero, need to mark this one as _no_reinit
+        self.dt_proj.bias._no_reinit = True
+
+        # S4D real initialization
+        # NOTE: why plus 1?
+        A = repeat(
+            torch.arange(1, self.d_state + 1, dtype=torch.float32, device=device),
+            "n -> d n",
+            d=self.d_inner,
+        ).contiguous()
+        A_log = torch.log(A)  # Keep A_log in fp32
+        self.A_log = nn.Parameter(A_log)
+        self.A_log._no_weight_decay = True
+
+        # D "skip" parameter
+        self.D = nn.Parameter(torch.ones(self.d_inner, device=device))  # Keep in fp32
+        self.D._no_weight_decay = True
+
+        # bidirectional
+        # forked from https://github.com/hustvl/Vim
+        if self.bimamba:
+            A_b = repeat(
+                torch.arange(1, self.d_state + 1, dtype=torch.float32, device=device),
+                "n -> d n",
+                d=self.d_inner,
+            ).contiguous()
+            A_b_log = torch.log(A_b)  # Keep A_b_log in fp32
+            self.A_b_log = nn.Parameter(A_b_log)
+            self.A_b_log._no_weight_decay = True 
+
+            self.conv1d_b = nn.Conv1d(
+                in_channels=self.d_inner,
+                out_channels=self.d_inner,
+                bias=conv_bias,
+                kernel_size=d_conv,
+                groups=self.d_inner,
+                padding=d_conv - 1,
+                **factory_kwargs,
+            )
+
+            self.x_proj_b = nn.Linear(
+                self.d_inner, self.dt_rank + self.d_state * 2, bias=False, **factory_kwargs
+            )
+            self.dt_proj_b = nn.Linear(self.dt_rank, self.d_inner, bias=True, **factory_kwargs)
+
+            self.D_b = nn.Parameter(torch.ones(self.d_inner, device=device))  # Keep in fp32
+            self.D_b._no_weight_decay = True
+
+        self.out_proj = nn.Linear(self.d_inner, self.d_model, bias=bias, **factory_kwargs)
+
+    def forward(self, hidden_states, inference_params=None, T=1):
+        """
+        hidden_states: (B, L, D)
+        Returns: same shape as hidden_states
+        """
+        batch, seqlen, dim = hidden_states.shape
+
+        conv_state, ssm_state = None, None
+        if inference_params is not None:
+            conv_state, ssm_state = self._get_states_from_cache(inference_params, batch)
+            if inference_params.seqlen_offset > 0:
+                # The states are updated inplace
+                out, _, _ = self.step(hidden_states, conv_state, ssm_state)
+                return out
+
+        # We do matmul and transpose BLH -> HBL at the same time
+        # NOTE: same as in_proj(hidden_states) but memory-efficient with the following operations
+        xz = rearrange(
+            self.in_proj.weight @ rearrange(hidden_states, "b l d -> d (b l)"),
+            "d (b l) -> b d l",
+            l=seqlen,
+        )
+        if self.in_proj.bias is not None:
+            xz = xz + rearrange(self.in_proj.bias.to(dtype=xz.dtype), "d -> d 1")
+
+        A = -torch.exp(self.A_log.float())  # (d_inner, d_state)
+        # In the backward pass we write dx and dz next to each other to avoid torch.cat
+        if self.use_fast_path and inference_params is None:  # Doesn't support outputting the states
+            if self.bimamba:
+                A_b = -torch.exp(self.A_b_log.float())
+                out = mamba_inner_fn_no_out_proj(
+                    xz,
+                    self.conv1d.weight,
+                    self.conv1d.bias,
+                    self.x_proj.weight,
+                    self.dt_proj.weight,
+                    A,
+                    None,  # input-dependent B
+                    None,  # input-dependent C
+                    self.D.float(),
+                    delta_bias=self.dt_proj.bias.float(),
+                    delta_softplus=True,
+                )
+                out_b = mamba_inner_fn_no_out_proj(
+                    xz.flip([-1]),
+                    self.conv1d_b.weight,
+                    self.conv1d_b.bias,
+                    self.x_proj_b.weight,
+                    self.dt_proj_b.weight,
+                    A_b,
+                    None,
+                    None,
+                    self.D_b.float(),
+                    delta_bias=self.dt_proj_b.bias.float(),
+                    delta_softplus=True,
+                )
+                out = F.linear(rearrange(out + out_b.flip([-1]), "b d l -> b l d"), self.out_proj.weight, self.out_proj.bias)
+            else:
+                out = mamba_inner_fn(
+                    xz,
+                    self.conv1d.weight,
+                    self.conv1d.bias,
+                    self.x_proj.weight,
+                    self.dt_proj.weight,
+                    self.out_proj.weight,
+                    self.out_proj.bias,
+                    A,
+                    None,  # input-dependent B
+                    None,  # input-dependent C
+                    self.D.float(),
+                    delta_bias=self.dt_proj.bias.float(),
+                    delta_softplus=True,
+                )
+        else:
+            x, z = xz.chunk(2, dim=1)
+            # Compute short convolution
+            if conv_state is not None:
+                conv_state.copy_(x[:, :, -self.d_conv :])  # Update state (B D W)
+            if causal_conv1d_fn is None:
+                x = self.act(self.conv1d(x)[..., :seqlen])
+            else:
+                assert self.activation in ["silu", "swish"]
+                x = causal_conv1d_fn(
+                    x,
+                    rearrange(self.conv1d.weight, "d 1 w -> d w"),
+                    self.conv1d.bias,
+                    self.activation,
+                )
+
+            # We're careful here about the layout, to avoid extra transposes.
+            # We want dt to have d as the slowest moving dimension
+            # and L as the fastest moving dimension, since those are what the ssm_scan kernel expects.
+            x_dbl = self.x_proj(rearrange(x, "b d l -> (b l) d"))  # (bl d)
+            dt, B, C = torch.split(x_dbl, [self.dt_rank, self.d_state, self.d_state], dim=-1)
+            dt = self.dt_proj.weight @ dt.t()
+            dt = rearrange(dt, "d (b l) -> b d l", l=seqlen)
+            B = rearrange(B, "(b l) dstate -> b dstate l", l=seqlen).contiguous()
+            C = rearrange(C, "(b l) dstate -> b dstate l", l=seqlen).contiguous()
+            assert self.activation in ["silu", "swish"]
+            y = selective_scan_fn(
+                x,
+                dt,
+                A,
+                B,
+                C,
+                self.D.float(),
+                z=z,
+                delta_bias=self.dt_proj.bias.float(),
+                delta_softplus=True,
+                return_last_state=ssm_state is not None,
+            )
+            if ssm_state is not None:
+                y, last_state = y
+                ssm_state.copy_(last_state)
+            y = rearrange(y, "b d l -> b l d")
+            out = self.out_proj(y)
+        return out
+
+    def step(self, hidden_states, conv_state, ssm_state):
+        dtype = hidden_states.dtype
+        assert hidden_states.shape[1] == 1, "Only support decoding with 1 token at a time for now"
+        xz = self.in_proj(hidden_states.squeeze(1))  # (B 2D)
+        x, z = xz.chunk(2, dim=-1)  # (B D)
+
+        # Conv step
+        if causal_conv1d_update is None:
+            conv_state.copy_(torch.roll(conv_state, shifts=-1, dims=-1))  # Update state (B D W)
+            conv_state[:, :, -1] = x
+            x = torch.sum(conv_state * rearrange(self.conv1d.weight, "d 1 w -> d w"), dim=-1)  # (B D)
+            if self.conv1d.bias is not None:
+                x = x + self.conv1d.bias
+            x = self.act(x).to(dtype=dtype)
+        else:
+            x = causal_conv1d_update(
+                x,
+                conv_state,
+                rearrange(self.conv1d.weight, "d 1 w -> d w"),
+                self.conv1d.bias,
+                self.activation,
+            )
+
+        x_db = self.x_proj(x)  # (B dt_rank+2*d_state)
+        dt, B, C = torch.split(x_db, [self.dt_rank, self.d_state, self.d_state], dim=-1)
+        # Don't add dt_bias here
+        dt = F.linear(dt, self.dt_proj.weight)  # (B d_inner)
+        A = -torch.exp(self.A_log.float())  # (d_inner, d_state)
+
+        # SSM step
+        if selective_state_update is None:
+            # Discretize A and B
+            dt = F.softplus(dt + self.dt_proj.bias.to(dtype=dt.dtype))
+            dA = torch.exp(torch.einsum("bd,dn->bdn", dt, A))
+            dB = torch.einsum("bd,bn->bdn", dt, B)
+            ssm_state.copy_(ssm_state * dA + rearrange(x, "b d -> b d 1") * dB)
+            y = torch.einsum("bdn,bn->bd", ssm_state.to(dtype), C)
+            y = y + self.D.to(dtype) * x
+            y = y * self.act(z)  # (B D)
+        else:
+            y = selective_state_update(
+                ssm_state, x, dt, A, B, C, self.D, z=z, dt_bias=self.dt_proj.bias, dt_softplus=True
+            )
+
+        out = self.out_proj(y)
+        return out.unsqueeze(1), conv_state, ssm_state
+
+    def allocate_inference_cache(self, batch_size, max_seqlen, dtype=None, **kwargs):
+        device = self.out_proj.weight.device
+        conv_dtype = self.conv1d.weight.dtype if dtype is None else dtype
+        conv_state = torch.zeros(
+            batch_size, self.d_model * self.expand, self.d_conv, device=device, dtype=conv_dtype
+        )
+        ssm_dtype = self.dt_proj.weight.dtype if dtype is None else dtype
+        # ssm_dtype = torch.float32
+        ssm_state = torch.zeros(
+            batch_size, self.d_model * self.expand, self.d_state, device=device, dtype=ssm_dtype
+        )
+        return conv_state, ssm_state
+
+    def _get_states_from_cache(self, inference_params, batch_size, initialize_states=False):
+        assert self.layer_idx is not None
+        if self.layer_idx not in inference_params.key_value_memory_dict:
+            batch_shape = (batch_size,)
+            conv_state = torch.zeros(
+                batch_size,
+                self.d_model * self.expand,
+                self.d_conv,
+                device=self.conv1d.weight.device,
+                dtype=self.conv1d.weight.dtype,
+            )
+            ssm_state = torch.zeros(
+                batch_size,
+                self.d_model * self.expand,
+                self.d_state,
+                device=self.dt_proj.weight.device,
+                dtype=self.dt_proj.weight.dtype,
+                # dtype=torch.float32,
+            )
+            inference_params.key_value_memory_dict[self.layer_idx] = (conv_state, ssm_state)
+        else:
+            conv_state, ssm_state = inference_params.key_value_memory_dict[self.layer_idx]
+            # TODO: What if batch size changes between generation, and we reuse the same states?
+            if initialize_states:
+                conv_state.zero_()
+                ssm_state.zero_()
+        return conv_state, ssm_state
+
+
+class Block(nn.Module):
+    def __init__(
+        self, dim, mixer_cls, norm_cls=nn.LayerNorm, fused_add_norm=False, residual_in_fp32=False
+    ):
+        """
+        Simple block wrapping a mixer class with LayerNorm/RMSNorm and residual connection"
+
+        This Block has a slightly different structure compared to a regular
+        prenorm Transformer block.
+        The standard block is: LN -> MHA/MLP -> Add.
+        [Ref: https://arxiv.org/abs/2002.04745]
+        Here we have: Add -> LN -> Mixer, returning both
+        the hidden_states (output of the mixer) and the residual.
+        This is purely for performance reasons, as we can fuse add and LayerNorm.
+        The residual needs to be provided (except for the very first block).
+        """
+        super().__init__()
+        self.residual_in_fp32 = residual_in_fp32
+        self.fused_add_norm = fused_add_norm
+        self.mixer = mixer_cls(dim)
+        self.norm = norm_cls(dim)
+        if self.fused_add_norm:
+            assert RMSNorm is not None, "RMSNorm import fails"
+            assert isinstance(
+                self.norm, (nn.LayerNorm, RMSNorm)
+            ), "Only LayerNorm and RMSNorm are supported for fused_add_norm"
+
+    def forward(
+        self, hidden_states: Tensor, residual: Optional[Tensor] = None, inference_params=None
+    ):
+        r"""Pass the input through the encoder layer.
+
+        Args:
+            hidden_states: the sequence to the encoder layer (required).
+            residual: hidden_states = Mixer(LN(residual))
+        """
+        if not self.fused_add_norm:
+            residual = (hidden_states + residual) if residual is not None else hidden_states
+            hidden_states = self.norm(residual.to(dtype=self.norm.weight.dtype))
+            if self.residual_in_fp32:
+                residual = residual.to(torch.float32)
+        else:
+            fused_add_norm_fn = rms_norm_fn if isinstance(self.norm, RMSNorm) else layer_norm_fn
+            hidden_states, residual = fused_add_norm_fn(
+                hidden_states,
+                self.norm.weight,
+                self.norm.bias,
+                residual=residual,
+                prenorm=True,
+                residual_in_fp32=self.residual_in_fp32,
+                eps=self.norm.eps,
+            )
+        hidden_states = self.mixer(hidden_states, inference_params=inference_params)
+        return hidden_states, residual
+
+    def allocate_inference_cache(self, batch_size, max_seqlen, dtype=None, **kwargs):
+        return self.mixer.allocate_inference_cache(batch_size, max_seqlen, dtype=dtype, **kwargs)

mamba/mamba_ssm/ops/selective_scan_interface.py

@@ -0,0 +1,709 @@
+# Copyright (c) 2023, Tri Dao, Albert Gu.
+
+import torch
+import torch.nn.functional as F
+from torch.cuda.amp import custom_bwd, custom_fwd
+
+from einops import rearrange, repeat
+
+from causal_conv1d import causal_conv1d_fn
+import causal_conv1d_cuda
+import selective_scan_cuda
+
+
+class SelectiveScanFn(torch.autograd.Function):
+
+    @staticmethod
+    def forward(ctx, u, delta, A, B, C, D=None, z=None, delta_bias=None, delta_softplus=False,
+                return_last_state=False):
+        if u.stride(-1) != 1:
+            u = u.contiguous()
+        if delta.stride(-1) != 1:
+            delta = delta.contiguous()
+        if D is not None:
+            D = D.contiguous()
+        if B.stride(-1) != 1:
+            B = B.contiguous()
+        if C.stride(-1) != 1:
+            C = C.contiguous()
+        if z is not None and z.stride(-1) != 1:
+            z = z.contiguous()
+        if B.dim() == 3:
+            B = rearrange(B, "b dstate l -> b 1 dstate l")
+            ctx.squeeze_B = True
+        if C.dim() == 3:
+            C = rearrange(C, "b dstate l -> b 1 dstate l")
+            ctx.squeeze_C = True
+        out, x, *rest = selective_scan_cuda.fwd(u, delta, A, B, C, D, z, delta_bias, delta_softplus)
+        ctx.delta_softplus = delta_softplus
+        ctx.has_z = z is not None
+        last_state = x[:, :, -1, 1::2]  # (batch, dim, dstate)
+        if not ctx.has_z:
+            ctx.save_for_backward(u, delta, A, B, C, D, delta_bias, x)
+            return out if not return_last_state else (out, last_state)
+        else:
+            ctx.save_for_backward(u, delta, A, B, C, D, z, delta_bias, x, out)
+            out_z = rest[0]
+            return out_z if not return_last_state else (out_z, last_state)
+
+    @staticmethod
+    def backward(ctx, dout, *args):
+        if not ctx.has_z:
+            u, delta, A, B, C, D, delta_bias, x = ctx.saved_tensors
+            z = None
+            out = None
+        else:
+            u, delta, A, B, C, D, z, delta_bias, x, out = ctx.saved_tensors
+        if dout.stride(-1) != 1:
+            dout = dout.contiguous()
+        # The kernel supports passing in a pre-allocated dz (e.g., in case we want to fuse the
+        # backward of selective_scan_cuda with the backward of chunk).
+        # Here we just pass in None and dz will be allocated in the C++ code.
+        du, ddelta, dA, dB, dC, dD, ddelta_bias, *rest = selective_scan_cuda.bwd(
+            u, delta, A, B, C, D, z, delta_bias, dout, x, out, None, ctx.delta_softplus,
+            False  # option to recompute out_z, not used here
+        )
+        dz = rest[0] if ctx.has_z else None
+        dB = dB.squeeze(1) if getattr(ctx, "squeeze_B", False) else dB
+        dC = dC.squeeze(1) if getattr(ctx, "squeeze_C", False) else dC
+        return (du, ddelta, dA, dB, dC,
+                dD if D is not None else None,
+                dz,
+                ddelta_bias if delta_bias is not None else None,
+                None,
+                None)
+
+
+def selective_scan_fn(u, delta, A, B, C, D=None, z=None, delta_bias=None, delta_softplus=False,
+                     return_last_state=False):
+    """if return_last_state is True, returns (out, last_state)
+    last_state has shape (batch, dim, dstate). Note that the gradient of the last state is
+    not considered in the backward pass.
+    """
+    return SelectiveScanFn.apply(u, delta, A, B, C, D, z, delta_bias, delta_softplus, return_last_state)
+
+
+def selective_scan_ref(u, delta, A, B, C, D=None, z=None, delta_bias=None, delta_softplus=False,
+                      return_last_state=False):
+    """
+    u: r(B D L)
+    delta: r(B D L)
+    A: c(D N) or r(D N)
+    B: c(D N) or r(B N L) or r(B N 2L) or r(B G N L) or (B G N L)
+    C: c(D N) or r(B N L) or r(B N 2L) or r(B G N L) or (B G N L)
+    D: r(D)
+    z: r(B D L)
+    delta_bias: r(D), fp32
+
+    out: r(B D L)
+    last_state (optional): r(B D dstate) or c(B D dstate)
+    """
+    dtype_in = u.dtype
+    u = u.float()
+    delta = delta.float()
+    if delta_bias is not None:
+        delta = delta + delta_bias[..., None].float()
+    if delta_softplus:
+        delta = F.softplus(delta)
+    batch, dim, dstate = u.shape[0], A.shape[0], A.shape[1]
+    is_variable_B = B.dim() >= 3
+    is_variable_C = C.dim() >= 3
+    if A.is_complex():
+        if is_variable_B:
+            B = torch.view_as_complex(rearrange(B.float(), "... (L two) -> ... L two", two=2))
+        if is_variable_C:
+            C = torch.view_as_complex(rearrange(C.float(), "... (L two) -> ... L two", two=2))
+    else:
+        B = B.float()
+        C = C.float()
+    x = A.new_zeros((batch, dim, dstate))
+    ys = []
+    deltaA = torch.exp(torch.einsum('bdl,dn->bdln', delta, A))
+    if not is_variable_B:
+        deltaB_u = torch.einsum('bdl,dn,bdl->bdln', delta, B, u)
+    else:
+        if B.dim() == 3:
+            deltaB_u = torch.einsum('bdl,bnl,bdl->bdln', delta, B, u)
+        else:
+            B = repeat(B, "B G N L -> B (G H) N L", H=dim // B.shape[1])
+            deltaB_u = torch.einsum('bdl,bdnl,bdl->bdln', delta, B, u)
+    if is_variable_C and C.dim() == 4:
+        C = repeat(C, "B G N L -> B (G H) N L", H=dim // C.shape[1])
+    last_state = None
+    for i in range(u.shape[2]):
+        x = deltaA[:, :, i] * x + deltaB_u[:, :, i]
+        if not is_variable_C:
+            y = torch.einsum('bdn,dn->bd', x, C)
+        else:
+            if C.dim() == 3:
+                y = torch.einsum('bdn,bn->bd', x, C[:, :, i])
+            else:
+                y = torch.einsum('bdn,bdn->bd', x, C[:, :, :, i])
+        if i == u.shape[2] - 1:
+            last_state = x
+        if y.is_complex():
+            y = y.real * 2
+        ys.append(y)
+    y = torch.stack(ys, dim=2) # (batch dim L)
+    out = y if D is None else y + u * rearrange(D, "d -> d 1")
+    if z is not None:
+        out = out * F.silu(z)
+    out = out.to(dtype=dtype_in)
+    return out if not return_last_state else (out, last_state)
+
+
+class MambaInnerFnNoOutProj(torch.autograd.Function):
+
+    @staticmethod
+    @custom_fwd
+    def forward(ctx, xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+                A, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+                C_proj_bias=None, delta_softplus=True, checkpoint_lvl=1):
+        """
+             xz: (batch, dim, seqlen)
+        """
+        assert checkpoint_lvl in [0, 1]
+        L = xz.shape[-1]
+        delta_rank = delta_proj_weight.shape[1]
+        d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+        if torch.is_autocast_enabled():
+            x_proj_weight = x_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            delta_proj_weight = delta_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+        if xz.stride(-1) != 1:
+            xz = xz.contiguous()
+        conv1d_weight = rearrange(conv1d_weight, "d 1 w -> d w")
+        x, z = xz.chunk(2, dim=1)
+        conv1d_bias = conv1d_bias.contiguous() if conv1d_bias is not None else None
+        conv1d_out = causal_conv1d_cuda.causal_conv1d_fwd(x, conv1d_weight, conv1d_bias, True)
+        # We're being very careful here about the layout, to avoid extra transposes.
+        # We want delta to have d as the slowest moving dimension
+        # and L as the fastest moving dimension, since those are what the ssm_scan kernel expects.
+        x_dbl = F.linear(rearrange(conv1d_out, 'b d l -> (b l) d'), x_proj_weight)  # (bl d)
+        delta = rearrange(delta_proj_weight @ x_dbl[:, :delta_rank].t(), "d (b l) -> b d l", l = L)
+        ctx.is_variable_B = B is None
+        ctx.is_variable_C = C is None
+        ctx.B_proj_bias_is_None = B_proj_bias is None
+        ctx.C_proj_bias_is_None = C_proj_bias is None
+        if B is None:  # variable B
+            B = x_dbl[:, delta_rank:delta_rank + d_state]  # (bl dstate)
+            if B_proj_bias is not None:
+                B = B + B_proj_bias.to(dtype=B.dtype)
+            if not A.is_complex():
+                # B = rearrange(B, "(b l) dstate -> b dstate l", l=L).contiguous()
+                B = rearrange(B, "(b l) dstate -> b 1 dstate l", l=L).contiguous()
+            else:
+                B = rearrange(B, "(b l) (dstate two) -> b 1 dstate (l two)", l=L, two=2).contiguous()
+        else:
+            if B.stride(-1) != 1:
+                B = B.contiguous()
+        if C is None:  # variable C
+            C = x_dbl[:, -d_state:]  # (bl dstate)
+            if C_proj_bias is not None:
+                C = C + C_proj_bias.to(dtype=C.dtype)
+            if not A.is_complex():
+                # C = rearrange(C, "(b l) dstate -> b dstate l", l=L).contiguous()
+                C = rearrange(C, "(b l) dstate -> b 1 dstate l", l=L).contiguous()
+            else:
+                C = rearrange(C, "(b l) (dstate two) -> b 1 dstate (l two)", l=L, two=2).contiguous()
+        else:
+            if C.stride(-1) != 1:
+                C = C.contiguous()
+        if D is not None:
+            D = D.contiguous()
+        out, scan_intermediates, out_z = selective_scan_cuda.fwd(
+            conv1d_out, delta, A, B, C, D, z, delta_bias, delta_softplus
+        )
+        ctx.delta_softplus = delta_softplus
+        ctx.checkpoint_lvl = checkpoint_lvl
+        if checkpoint_lvl >= 1:  # Will recompute conv1d_out and delta in the backward pass
+            conv1d_out, delta = None, None
+        ctx.save_for_backward(xz, conv1d_weight, conv1d_bias, x_dbl, x_proj_weight,
+                              delta_proj_weight, conv1d_out, delta,
+                              A, B, C, D, delta_bias, scan_intermediates, out)
+        # return rearrange(out_z, "b d l -> b l d")
+        return out_z
+
+    @staticmethod
+    @custom_bwd
+    def backward(ctx, dout):
+        # dout: (batch, seqlen, dim)
+        (xz, conv1d_weight, conv1d_bias, x_dbl, x_proj_weight, delta_proj_weight, 
+         conv1d_out, delta, A, B, C, D, delta_bias, scan_intermediates, out) = ctx.saved_tensors
+        L = xz.shape[-1]
+        delta_rank = delta_proj_weight.shape[1]
+        d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+        x, z = xz.chunk(2, dim=1)
+        if dout.stride(-1) != 1:
+            dout = dout.contiguous()
+        if ctx.checkpoint_lvl == 1:
+            conv1d_out = causal_conv1d_cuda.causal_conv1d_fwd(x, conv1d_weight, conv1d_bias, True)
+            delta = rearrange(delta_proj_weight @ x_dbl[:, :delta_rank].t(),
+                              "d (b l) -> b d l", l = L)
+        # The kernel supports passing in a pre-allocated dz (e.g., in case we want to fuse the
+        # backward of selective_scan_cuda with the backward of chunk).
+        dxz = torch.empty_like(xz)  # (batch, dim, seqlen)
+        dx, dz = dxz.chunk(2, dim=1)
+        # dout_y = rearrange(dout, "b l d -> b d l") # because no arrange at end of forward, so dout shape is b d l
+        dconv1d_out, ddelta, dA, dB, dC, dD, ddelta_bias, dz, out_z = selective_scan_cuda.bwd(
+            conv1d_out, delta, A, B, C, D, z, delta_bias, dout, scan_intermediates, out, dz,
+            ctx.delta_softplus,
+            True  # option to recompute out_z
+        )
+        dD = dD if D is not None else None
+        dx_dbl = torch.empty_like(x_dbl)
+        dB_proj_bias = None
+        if ctx.is_variable_B:
+            if not A.is_complex():
+                dB = rearrange(dB, "b 1 dstate l -> (b l) dstate").contiguous()
+            else:
+                dB = rearrange(dB, "b 1 dstate (l two) -> (b l) (dstate two)", two=2).contiguous()
+            dB_proj_bias = dB.sum(0) if not ctx.B_proj_bias_is_None else None
+            dx_dbl[:, delta_rank:delta_rank + d_state] = dB  # (bl d)
+            dB = None
+        dC_proj_bias = None
+        if ctx.is_variable_C:
+            if not A.is_complex():
+                dC = rearrange(dC, "b 1 dstate l -> (b l) dstate").contiguous()
+            else:
+                dC = rearrange(dC, "b 1 dstate (l two) -> (b l) (dstate two)", two=2).contiguous()
+            dC_proj_bias = dC.sum(0) if not ctx.C_proj_bias_is_None else None
+            dx_dbl[:, -d_state:] = dC  # (bl d)
+            dC = None
+        ddelta = rearrange(ddelta, "b d l -> d (b l)")
+        ddelta_proj_weight = torch.einsum("dB,Br->dr", ddelta, x_dbl[:, :delta_rank])
+        dx_dbl[:, :delta_rank] = torch.einsum("dB,dr->Br", ddelta, delta_proj_weight)
+        dconv1d_out = rearrange(dconv1d_out, "b d l -> d (b l)")
+        dx_proj_weight = torch.einsum("Br,Bd->rd", dx_dbl, rearrange(conv1d_out, "b d l -> (b l) d"))
+        dconv1d_out = torch.addmm(dconv1d_out, x_proj_weight.t(), dx_dbl.t(), out=dconv1d_out)
+        dconv1d_out = rearrange(dconv1d_out, "d (b l) -> b d l", b=x.shape[0], l=x.shape[-1])
+        # The kernel supports passing in a pre-allocated dx (e.g., in case we want to fuse the
+        # backward of conv1d with the backward of chunk).
+        dx, dconv1d_weight, dconv1d_bias = causal_conv1d_cuda.causal_conv1d_bwd(
+            x, conv1d_weight, conv1d_bias, dconv1d_out, dx, True
+        )
+        dconv1d_bias = dconv1d_bias if conv1d_bias is not None else None
+        dconv1d_weight = rearrange(dconv1d_weight, "d w -> d 1 w")
+        return (dxz, dconv1d_weight, dconv1d_bias, dx_proj_weight, ddelta_proj_weight,
+                dA, dB, dC, dD,
+                ddelta_bias if delta_bias is not None else None,
+                dB_proj_bias, dC_proj_bias, None)
+    
+
+class MambaInnerFn(torch.autograd.Function):
+
+    @staticmethod
+    @custom_fwd
+    def forward(ctx, xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+                out_proj_weight, out_proj_bias,
+                A, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+                C_proj_bias=None, delta_softplus=True, checkpoint_lvl=1):
+        """
+             xz: (batch, dim, seqlen)
+        """
+        assert checkpoint_lvl in [0, 1]
+        L = xz.shape[-1]
+        delta_rank = delta_proj_weight.shape[1]
+        d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+        if torch.is_autocast_enabled():
+            x_proj_weight = x_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            delta_proj_weight = delta_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            out_proj_weight = out_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            out_proj_bias = (out_proj_bias.to(dtype=torch.get_autocast_gpu_dtype())
+                             if out_proj_bias is not None else None)
+        if xz.stride(-1) != 1:
+            xz = xz.contiguous()
+        conv1d_weight = rearrange(conv1d_weight, "d 1 w -> d w")
+        x, z = xz.chunk(2, dim=1)
+        conv1d_bias = conv1d_bias.contiguous() if conv1d_bias is not None else None
+        conv1d_out = causal_conv1d_cuda.causal_conv1d_fwd(x, conv1d_weight, conv1d_bias, True)
+        # We're being very careful here about the layout, to avoid extra transposes.
+        # We want delta to have d as the slowest moving dimension
+        # and L as the fastest moving dimension, since those are what the ssm_scan kernel expects.
+        x_dbl = F.linear(rearrange(conv1d_out, 'b d l -> (b l) d'), x_proj_weight)  # (bl d)
+        delta = rearrange(delta_proj_weight @ x_dbl[:, :delta_rank].t(), "d (b l) -> b d l", l = L)
+        ctx.is_variable_B = B is None
+        ctx.is_variable_C = C is None
+        ctx.B_proj_bias_is_None = B_proj_bias is None
+        ctx.C_proj_bias_is_None = C_proj_bias is None
+        if B is None:  # variable B
+            B = x_dbl[:, delta_rank:delta_rank + d_state]  # (bl dstate)
+            if B_proj_bias is not None:
+                B = B + B_proj_bias.to(dtype=B.dtype)
+            if not A.is_complex():
+                # B = rearrange(B, "(b l) dstate -> b dstate l", l=L).contiguous()
+                B = rearrange(B, "(b l) dstate -> b 1 dstate l", l=L).contiguous()
+            else:
+                B = rearrange(B, "(b l) (dstate two) -> b 1 dstate (l two)", l=L, two=2).contiguous()
+        else:
+            if B.stride(-1) != 1:
+                B = B.contiguous()
+        if C is None:  # variable C
+            C = x_dbl[:, -d_state:]  # (bl dstate)
+            if C_proj_bias is not None:
+                C = C + C_proj_bias.to(dtype=C.dtype)
+            if not A.is_complex():
+                # C = rearrange(C, "(b l) dstate -> b dstate l", l=L).contiguous()
+                C = rearrange(C, "(b l) dstate -> b 1 dstate l", l=L).contiguous()
+            else:
+                C = rearrange(C, "(b l) (dstate two) -> b 1 dstate (l two)", l=L, two=2).contiguous()
+        else:
+            if C.stride(-1) != 1:
+                C = C.contiguous()
+        if D is not None:
+            D = D.contiguous()
+        out, scan_intermediates, out_z = selective_scan_cuda.fwd(
+            conv1d_out, delta, A, B, C, D, z, delta_bias, delta_softplus
+        )
+        ctx.delta_softplus = delta_softplus
+        ctx.out_proj_bias_is_None = out_proj_bias is None
+        ctx.checkpoint_lvl = checkpoint_lvl
+        if checkpoint_lvl >= 1:  # Will recompute conv1d_out and delta in the backward pass
+            conv1d_out, delta = None, None
+        ctx.save_for_backward(xz, conv1d_weight, conv1d_bias, x_dbl, x_proj_weight,
+                              delta_proj_weight, out_proj_weight, conv1d_out, delta,
+                              A, B, C, D, delta_bias, scan_intermediates, out)
+        return F.linear(rearrange(out_z, "b d l -> b l d"), out_proj_weight, out_proj_bias)
+
+    @staticmethod
+    @custom_bwd
+    def backward(ctx, dout):
+        # dout: (batch, seqlen, dim)
+        (xz, conv1d_weight, conv1d_bias, x_dbl, x_proj_weight, delta_proj_weight, out_proj_weight,
+         conv1d_out, delta, A, B, C, D, delta_bias, scan_intermediates, out) = ctx.saved_tensors
+        L = xz.shape[-1]
+        delta_rank = delta_proj_weight.shape[1]
+        d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+        x, z = xz.chunk(2, dim=1)
+        if dout.stride(-1) != 1:
+            dout = dout.contiguous()
+        if ctx.checkpoint_lvl == 1:
+            conv1d_out = causal_conv1d_cuda.causal_conv1d_fwd(x, conv1d_weight, conv1d_bias, True)
+            delta = rearrange(delta_proj_weight @ x_dbl[:, :delta_rank].t(),
+                              "d (b l) -> b d l", l = L)
+        # The kernel supports passing in a pre-allocated dz (e.g., in case we want to fuse the
+        # backward of selective_scan_cuda with the backward of chunk).
+        dxz = torch.empty_like(xz)  # (batch, dim, seqlen)
+        dx, dz = dxz.chunk(2, dim=1)
+        dout = rearrange(dout, "b l e -> e (b l)")
+        dout_y = rearrange(out_proj_weight.t() @ dout, "d (b l) -> b d l", l=L)
+        dconv1d_out, ddelta, dA, dB, dC, dD, ddelta_bias, dz, out_z = selective_scan_cuda.bwd(
+            conv1d_out, delta, A, B, C, D, z, delta_bias, dout_y, scan_intermediates, out, dz,
+            ctx.delta_softplus,
+            True  # option to recompute out_z
+        )
+        dout_proj_weight = torch.einsum("eB,dB->ed", dout, rearrange(out_z, "b d l -> d (b l)"))
+        dout_proj_bias = dout.sum(dim=(0, 1)) if not ctx.out_proj_bias_is_None else None
+        dD = dD if D is not None else None
+        dx_dbl = torch.empty_like(x_dbl)
+        dB_proj_bias = None
+        if ctx.is_variable_B:
+            if not A.is_complex():
+                dB = rearrange(dB, "b 1 dstate l -> (b l) dstate").contiguous()
+            else:
+                dB = rearrange(dB, "b 1 dstate (l two) -> (b l) (dstate two)", two=2).contiguous()
+            dB_proj_bias = dB.sum(0) if not ctx.B_proj_bias_is_None else None
+            dx_dbl[:, delta_rank:delta_rank + d_state] = dB  # (bl d)
+            dB = None
+        dC_proj_bias = None
+        if ctx.is_variable_C:
+            if not A.is_complex():
+                dC = rearrange(dC, "b 1 dstate l -> (b l) dstate").contiguous()
+            else:
+                dC = rearrange(dC, "b 1 dstate (l two) -> (b l) (dstate two)", two=2).contiguous()
+            dC_proj_bias = dC.sum(0) if not ctx.C_proj_bias_is_None else None
+            dx_dbl[:, -d_state:] = dC  # (bl d)
+            dC = None
+        ddelta = rearrange(ddelta, "b d l -> d (b l)")
+        ddelta_proj_weight = torch.einsum("dB,Br->dr", ddelta, x_dbl[:, :delta_rank])
+        dx_dbl[:, :delta_rank] = torch.einsum("dB,dr->Br", ddelta, delta_proj_weight)
+        dconv1d_out = rearrange(dconv1d_out, "b d l -> d (b l)")
+        dx_proj_weight = torch.einsum("Br,Bd->rd", dx_dbl, rearrange(conv1d_out, "b d l -> (b l) d"))
+        dconv1d_out = torch.addmm(dconv1d_out, x_proj_weight.t(), dx_dbl.t(), out=dconv1d_out)
+        dconv1d_out = rearrange(dconv1d_out, "d (b l) -> b d l", b=x.shape[0], l=x.shape[-1])
+        # The kernel supports passing in a pre-allocated dx (e.g., in case we want to fuse the
+        # backward of conv1d with the backward of chunk).
+        dx, dconv1d_weight, dconv1d_bias = causal_conv1d_cuda.causal_conv1d_bwd(
+            x, conv1d_weight, conv1d_bias, dconv1d_out, dx, True
+        )
+        dconv1d_bias = dconv1d_bias if conv1d_bias is not None else None
+        dconv1d_weight = rearrange(dconv1d_weight, "d w -> d 1 w")
+        return (dxz, dconv1d_weight, dconv1d_bias, dx_proj_weight, ddelta_proj_weight,
+                dout_proj_weight, dout_proj_bias,
+                dA, dB, dC, dD,
+                ddelta_bias if delta_bias is not None else None,
+                dB_proj_bias, dC_proj_bias, None)
+
+
+class BiMambaInnerFn(torch.autograd.Function):
+
+    @staticmethod
+    @custom_fwd
+    def forward(ctx, xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+                out_proj_weight, out_proj_bias,
+                A, A_b, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+                C_proj_bias=None, delta_softplus=True, checkpoint_lvl=1):
+        """
+             xz: (batch, dim, seqlen)
+        """
+        assert checkpoint_lvl in [0, 1]
+        L = xz.shape[-1]
+        delta_rank = delta_proj_weight.shape[1]
+        d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+        if torch.is_autocast_enabled():
+            x_proj_weight = x_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            delta_proj_weight = delta_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            out_proj_weight = out_proj_weight.to(dtype=torch.get_autocast_gpu_dtype())
+            out_proj_bias = (out_proj_bias.to(dtype=torch.get_autocast_gpu_dtype())
+                             if out_proj_bias is not None else None)
+        if xz.stride(-1) != 1:
+            xz = xz.contiguous()
+        conv1d_weight = rearrange(conv1d_weight, "d 1 w -> d w")
+        x, z = xz.chunk(2, dim=1)
+        conv1d_bias = conv1d_bias.contiguous() if conv1d_bias is not None else None
+        conv1d_out = causal_conv1d_cuda.causal_conv1d_fwd(x, conv1d_weight, conv1d_bias, True)
+        # We're being very careful here about the layout, to avoid extra transposes.
+        # We want delta to have d as the slowest moving dimension
+        # and L as the fastest moving dimension, since those are what the ssm_scan kernel expects.
+        x_dbl = F.linear(rearrange(conv1d_out, 'b d l -> (b l) d'), x_proj_weight)  # (bl d)
+        delta = rearrange(delta_proj_weight @ x_dbl[:, :delta_rank].t(), "d (b l) -> b d l", l = L)
+        ctx.is_variable_B = B is None
+        ctx.is_variable_C = C is None
+        ctx.B_proj_bias_is_None = B_proj_bias is None
+        ctx.C_proj_bias_is_None = C_proj_bias is None
+        if B is None:  # variable B
+            B = x_dbl[:, delta_rank:delta_rank + d_state]  # (bl dstate)
+            if B_proj_bias is not None:
+                B = B + B_proj_bias.to(dtype=B.dtype)
+            if not A.is_complex():
+                # B = rearrange(B, "(b l) dstate -> b dstate l", l=L).contiguous()
+                B = rearrange(B, "(b l) dstate -> b 1 dstate l", l=L).contiguous()
+            else:
+                B = rearrange(B, "(b l) (dstate two) -> b 1 dstate (l two)", l=L, two=2).contiguous()
+        else:
+            if B.stride(-1) != 1:
+                B = B.contiguous()
+        if C is None:  # variable C
+            C = x_dbl[:, -d_state:]  # (bl dstate)
+            if C_proj_bias is not None:
+                C = C + C_proj_bias.to(dtype=C.dtype)
+            if not A.is_complex():
+                # C = rearrange(C, "(b l) dstate -> b dstate l", l=L).contiguous()
+                C = rearrange(C, "(b l) dstate -> b 1 dstate l", l=L).contiguous()
+            else:
+                C = rearrange(C, "(b l) (dstate two) -> b 1 dstate (l two)", l=L, two=2).contiguous()
+        else:
+            if C.stride(-1) != 1:
+                C = C.contiguous()
+        if D is not None:
+            D = D.contiguous()
+        out_f, scan_intermediates_f, out_z_f = selective_scan_cuda.fwd(
+            conv1d_out, delta, A, B, C, D, z, delta_bias, delta_softplus
+        )
+        assert not A_b.is_complex(), "A should not be complex!!"
+        out_b, scan_intermediates_b, out_z_b = selective_scan_cuda.fwd(
+            conv1d_out.flip([-1]), delta.flip([-1]), A_b, B.flip([-1]), C.flip([-1]), D, z.flip([-1]), delta_bias, delta_softplus,
+        )
+
+        out_z = out_z_f + out_z_b.flip([-1])
+
+        ctx.delta_softplus = delta_softplus
+        ctx.out_proj_bias_is_None = out_proj_bias is None
+        ctx.checkpoint_lvl = checkpoint_lvl
+        if checkpoint_lvl >= 1:  # Will recompute conv1d_out and delta in the backward pass
+            conv1d_out, delta = None, None
+        ctx.save_for_backward(xz, conv1d_weight, conv1d_bias, x_dbl, x_proj_weight,
+                              delta_proj_weight, out_proj_weight, conv1d_out, delta,
+                              A, A_b, B, C, D, delta_bias, scan_intermediates_f, scan_intermediates_b, out_f, out_b)
+        return F.linear(rearrange(out_z, "b d l -> b l d"), out_proj_weight, out_proj_bias)
+
+    @staticmethod
+    @custom_bwd
+    def backward(ctx, dout):
+        # dout: (batch, seqlen, dim)
+        (xz, conv1d_weight, conv1d_bias, x_dbl, x_proj_weight, delta_proj_weight, out_proj_weight,
+         conv1d_out, delta, A, A_b, B, C, D, delta_bias, scan_intermediates_f, scan_intermediates_b, out_f, out_b) = ctx.saved_tensors
+        L = xz.shape[-1]
+        delta_rank = delta_proj_weight.shape[1]
+        d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+        x, z = xz.chunk(2, dim=1)
+        if dout.stride(-1) != 1:
+            dout = dout.contiguous()
+        if ctx.checkpoint_lvl == 1:
+            conv1d_out = causal_conv1d_cuda.causal_conv1d_fwd(x, conv1d_weight, conv1d_bias, True)
+            delta = rearrange(delta_proj_weight @ x_dbl[:, :delta_rank].t(),
+                              "d (b l) -> b d l", l = L)
+        # The kernel supports passing in a pre-allocated dz (e.g., in case we want to fuse the
+        # backward of selective_scan_cuda with the backward of chunk).
+        dxz = torch.empty_like(xz)  # (batch, dim, seqlen)
+        dx, dz = dxz.chunk(2, dim=1)
+        dout = rearrange(dout, "b l e -> e (b l)")
+        dout_y = rearrange(out_proj_weight.t() @ dout, "d (b l) -> b d l", l=L)
+        dconv1d_out, ddelta, dA, dB, dC, dD, ddelta_bias, dz, out_z_f = selective_scan_cuda.bwd(
+            conv1d_out, delta, A, B, C, D, z, delta_bias, dout_y, scan_intermediates_f, out_f, dz,
+            ctx.delta_softplus,
+            True  # option to recompute out_z
+        )
+        # flip one
+        dz_b = torch.empty_like(dz)
+        dconv1d_out_f_b, ddelta_f_b, dA_b, dB_f_b, dC_f_b, dD_b, ddelta_bias_b, dz_b, out_z_b = selective_scan_cuda.bwd(
+            conv1d_out.flip([-1]), delta.flip([-1]), A_b, B.flip([-1]), C.flip([-1]), D, z.flip([-1]), delta_bias, dout_y.flip([-1]), scan_intermediates_b, out_b, dz_b,
+            ctx.delta_softplus,
+            True  # option to recompute out_z
+        )
+
+        dconv1d_out = dconv1d_out + dconv1d_out_f_b.flip([-1])
+        ddelta = ddelta + ddelta_f_b.flip([-1])
+        dB = dB + dB_f_b.flip([-1])
+        dC = dC + dC_f_b.flip([-1])
+        dD = dD + dD_b
+        ddelta_bias = ddelta_bias + ddelta_bias_b
+        dz = dz + dz_b.flip([-1])
+        out_z = out_z_f + out_z_b.flip([-1])
+        
+        dout_proj_weight = torch.einsum("eB,dB->ed", dout, rearrange(out_z, "b d l -> d (b l)"))
+        dout_proj_bias = dout.sum(dim=(0, 1)) if not ctx.out_proj_bias_is_None else None
+        dD = dD if D is not None else None
+        dx_dbl = torch.empty_like(x_dbl)
+        dB_proj_bias = None
+        if ctx.is_variable_B:
+            if not A.is_complex():
+                dB = rearrange(dB, "b 1 dstate l -> (b l) dstate").contiguous()
+            else:
+                dB = rearrange(dB, "b 1 dstate (l two) -> (b l) (dstate two)", two=2).contiguous()
+            dB_proj_bias = dB.sum(0) if not ctx.B_proj_bias_is_None else None
+            dx_dbl[:, delta_rank:delta_rank + d_state] = dB  # (bl d)
+            dB = None
+        dC_proj_bias = None
+        if ctx.is_variable_C:
+            if not A.is_complex():
+                dC = rearrange(dC, "b 1 dstate l -> (b l) dstate").contiguous()
+            else:
+                dC = rearrange(dC, "b 1 dstate (l two) -> (b l) (dstate two)", two=2).contiguous()
+            dC_proj_bias = dC.sum(0) if not ctx.C_proj_bias_is_None else None
+            dx_dbl[:, -d_state:] = dC  # (bl d)
+            dC = None
+        ddelta = rearrange(ddelta, "b d l -> d (b l)")
+        ddelta_proj_weight = torch.einsum("dB,Br->dr", ddelta, x_dbl[:, :delta_rank])
+        dx_dbl[:, :delta_rank] = torch.einsum("dB,dr->Br", ddelta, delta_proj_weight)
+        dconv1d_out = rearrange(dconv1d_out, "b d l -> d (b l)")
+        dx_proj_weight = torch.einsum("Br,Bd->rd", dx_dbl, rearrange(conv1d_out, "b d l -> (b l) d"))
+        dconv1d_out = torch.addmm(dconv1d_out, x_proj_weight.t(), dx_dbl.t(), out=dconv1d_out)
+        dconv1d_out = rearrange(dconv1d_out, "d (b l) -> b d l", b=x.shape[0], l=x.shape[-1])
+        # The kernel supports passing in a pre-allocated dx (e.g., in case we want to fuse the
+        # backward of conv1d with the backward of chunk).
+        dx, dconv1d_weight, dconv1d_bias = causal_conv1d_cuda.causal_conv1d_bwd(
+            x, conv1d_weight, conv1d_bias, dconv1d_out, dx, True
+        )
+        dconv1d_bias = dconv1d_bias if conv1d_bias is not None else None
+        dconv1d_weight = rearrange(dconv1d_weight, "d w -> d 1 w")
+        return (dxz, dconv1d_weight, dconv1d_bias, dx_proj_weight, ddelta_proj_weight,
+                dout_proj_weight, dout_proj_bias,
+                dA, dA_b, dB, dC, dD,
+                ddelta_bias if delta_bias is not None else None,
+                dB_proj_bias, dC_proj_bias, None)
+    
+
+def mamba_inner_fn(
+    xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+    out_proj_weight, out_proj_bias,
+    A, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+    C_proj_bias=None, delta_softplus=True
+):
+    return MambaInnerFn.apply(xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+                              out_proj_weight, out_proj_bias,
+                              A, B, C, D, delta_bias, B_proj_bias, C_proj_bias, delta_softplus)
+
+def bimamba_inner_fn(
+    xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+    out_proj_weight, out_proj_bias,
+    A, A_b, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+    C_proj_bias=None, delta_softplus=True
+):
+    return BiMambaInnerFn.apply(xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+                              out_proj_weight, out_proj_bias,
+                              A, A_b, B, C, D, delta_bias, B_proj_bias, C_proj_bias, delta_softplus)
+
+
+def mamba_inner_fn_no_out_proj(
+    xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+    A, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+    C_proj_bias=None, delta_softplus=True
+):
+    return MambaInnerFnNoOutProj.apply(xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+                              A, B, C, D, delta_bias, B_proj_bias, C_proj_bias, delta_softplus)
+
+
+def mamba_inner_ref(
+    xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+    out_proj_weight, out_proj_bias,
+    A, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+    C_proj_bias=None, delta_softplus=True
+):
+    L = xz.shape[-1]
+    delta_rank = delta_proj_weight.shape[1]
+    d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+    x, z = xz.chunk(2, dim=1)
+    x = causal_conv1d_fn(x, rearrange(conv1d_weight, "d 1 w -> d w"), conv1d_bias, "silu")
+    # We're being very careful here about the layout, to avoid extra transposes.
+    # We want delta to have d as the slowest moving dimension
+    # and L as the fastest moving dimension, since those are what the ssm_scan kernel expects.
+    x_dbl = F.linear(rearrange(x, 'b d l -> (b l) d'), x_proj_weight)  # (bl d)
+    delta = delta_proj_weight @ x_dbl[:, :delta_rank].t()
+    delta = rearrange(delta, "d (b l) -> b d l", l=L)
+    if B is None:  # variable B
+        B = x_dbl[:, delta_rank:delta_rank + d_state]  # (bl d)
+        if B_proj_bias is not None:
+            B = B + B_proj_bias.to(dtype=B.dtype)
+        if not A.is_complex():
+            B = rearrange(B, "(b l) dstate -> b dstate l", l=L).contiguous()
+        else:
+            B = rearrange(B, "(b l) (dstate two) -> b dstate (l two)", l=L, two=2).contiguous()
+    if C is None:  # variable B
+        C = x_dbl[:, -d_state:]  # (bl d)
+        if C_proj_bias is not None:
+            C = C + C_proj_bias.to(dtype=C.dtype)
+        if not A.is_complex():
+            C = rearrange(C, "(b l) dstate -> b dstate l", l=L).contiguous()
+        else:
+            C = rearrange(C, "(b l) (dstate two) -> b dstate (l two)", l=L, two=2).contiguous()
+    y = selective_scan_fn(x, delta, A, B, C, D, z=z, delta_bias=delta_bias, delta_softplus=True)
+    return F.linear(rearrange(y, "b d l -> b l d"), out_proj_weight, out_proj_bias)
+
+
+def bimamba_inner_ref(
+    xz, conv1d_weight, conv1d_bias, x_proj_weight, delta_proj_weight,
+    out_proj_weight, out_proj_bias,
+    A, A_b, B=None, C=None, D=None, delta_bias=None, B_proj_bias=None,
+    C_proj_bias=None, delta_softplus=True
+):
+    L = xz.shape[-1]
+    delta_rank = delta_proj_weight.shape[1]
+    d_state = A.shape[-1] * (1 if not A.is_complex() else 2)
+    x, z = xz.chunk(2, dim=1)
+    x = causal_conv1d_fn(x, rearrange(conv1d_weight, "d 1 w -> d w"), conv1d_bias, "silu")
+    # We're being very careful here about the layout, to avoid extra transposes.
+    # We want delta to have d as the slowest moving dimension
+    # and L as the fastest moving dimension, since those are what the ssm_scan kernel expects.
+    x_dbl = F.linear(rearrange(x, 'b d l -> (b l) d'), x_proj_weight)  # (bl d)
+    delta = delta_proj_weight @ x_dbl[:, :delta_rank].t()
+    delta = rearrange(delta, "d (b l) -> b d l", l=L)
+    if B is None:  # variable B
+        B = x_dbl[:, delta_rank:delta_rank + d_state]  # (bl d)
+        if B_proj_bias is not None:
+            B = B + B_proj_bias.to(dtype=B.dtype)
+        if not A.is_complex():
+            B = rearrange(B, "(b l) dstate -> b dstate l", l=L).contiguous()
+        else:
+            B = rearrange(B, "(b l) (dstate two) -> b dstate (l two)", l=L, two=2).contiguous()
+    if C is None:  # variable B
+        C = x_dbl[:, -d_state:]  # (bl d)
+        if C_proj_bias is not None:
+            C = C + C_proj_bias.to(dtype=C.dtype)
+        if not A.is_complex():
+            C = rearrange(C, "(b l) dstate -> b dstate l", l=L).contiguous()
+        else:
+            C = rearrange(C, "(b l) (dstate two) -> b dstate (l two)", l=L, two=2).contiguous()
+    y = selective_scan_fn(x, delta, A, B, C, D, z=z, delta_bias=delta_bias, delta_softplus=True)
+    y_b = selective_scan_fn(x.flip([-1]), delta.flip([-1]), A_b, B.flip([-1]), C.flip([-1]), D, z.flip([-1]), delta_bias, delta_softplus=True)
+    y = y + y_b.flip([-1])
+    return F.linear(rearrange(y, "b d l -> b l d"), out_proj_weight, out_proj_bias)

mamba/mamba_ssm/ops/triton/layernorm.py

@@ -0,0 +1,636 @@
+# Copyright (c) 2023, Tri Dao.
+# Implement residual + layer_norm / rms_norm.
+
+# Based on the Triton LayerNorm tutorial: https://triton-lang.org/main/getting-started/tutorials/05-layer-norm.html
+# For the backward pass, we keep weight_grad and bias_grad in registers and accumulate.
+# This is faster for dimensions up to 8k, but after that it's much slower due to register spilling.
+# The models we train have hidden dim up to 8k anyway (e.g. Llama 70B), so this is fine.
+
+import math
+
+import torch
+import torch.nn.functional as F
+from torch.cuda.amp import custom_fwd, custom_bwd
+
+import triton
+import triton.language as tl
+
+
+def layer_norm_ref(x, weight, bias, residual=None, eps=1e-6, prenorm=False, upcast=False):
+    dtype = x.dtype
+    if upcast:
+        weight = weight.float()
+        bias = bias.float() if bias is not None else None
+    if upcast:
+        x = x.float()
+        residual = residual.float() if residual is not None else residual
+    if residual is not None:
+        x = (x + residual).to(x.dtype)
+    out = F.layer_norm(x.to(weight.dtype), x.shape[-1:], weight=weight, bias=bias, eps=eps).to(
+        dtype
+    )
+    return out if not prenorm else (out, x)
+
+
+def rms_norm_ref(x, weight, bias, residual=None, eps=1e-6, prenorm=False, upcast=False):
+    dtype = x.dtype
+    if upcast:
+        weight = weight.float()
+        bias = bias.float() if bias is not None else None
+    if upcast:
+        x = x.float()
+        residual = residual.float() if residual is not None else residual
+    if residual is not None:
+        x = (x + residual).to(x.dtype)
+    rstd = 1 / torch.sqrt((x.square()).mean(dim=-1, keepdim=True) + eps)
+    out = (x * rstd * weight) + bias if bias is not None else (x * rstd * weight)
+    out = out.to(dtype)
+    return out if not prenorm else (out, x)
+
+
+@triton.autotune(
+    configs=[
+        triton.Config({}, num_warps=1),
+        triton.Config({}, num_warps=2),
+        triton.Config({}, num_warps=4),
+        triton.Config({}, num_warps=8),
+        triton.Config({}, num_warps=16),
+        triton.Config({}, num_warps=32),
+    ],
+    key=["N", "HAS_RESIDUAL", "STORE_RESIDUAL_OUT", "IS_RMS_NORM", "HAS_BIAS"],
+)
+# @triton.heuristics({"HAS_BIAS": lambda args: args["B"] is not None})
+# @triton.heuristics({"HAS_RESIDUAL": lambda args: args["RESIDUAL"] is not None})
+@triton.jit
+def _layer_norm_fwd_1pass_kernel(
+    X,  # pointer to the input
+    Y,  # pointer to the output
+    W,  # pointer to the weights
+    B,  # pointer to the biases
+    RESIDUAL,  # pointer to the residual
+    RESIDUAL_OUT,  # pointer to the residual
+    Mean,  # pointer to the mean
+    Rstd,  # pointer to the 1/std
+    stride_x_row,  # how much to increase the pointer when moving by 1 row
+    stride_y_row,
+    stride_res_row,
+    stride_res_out_row,
+    N,  # number of columns in X
+    eps,  # epsilon to avoid division by zero
+    IS_RMS_NORM: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    HAS_RESIDUAL: tl.constexpr,
+    STORE_RESIDUAL_OUT: tl.constexpr,
+    HAS_BIAS: tl.constexpr,
+):
+    # Map the program id to the row of X and Y it should compute.
+    row = tl.program_id(0)
+    X += row * stride_x_row
+    Y += row * stride_y_row
+    if HAS_RESIDUAL:
+        RESIDUAL += row * stride_res_row
+    if STORE_RESIDUAL_OUT:
+        RESIDUAL_OUT += row * stride_res_out_row
+    # Compute mean and variance
+    cols = tl.arange(0, BLOCK_N)
+    x = tl.load(X + cols, mask=cols < N, other=0.0).to(tl.float32)
+    if HAS_RESIDUAL:
+        residual = tl.load(RESIDUAL + cols, mask=cols < N, other=0.0).to(tl.float32)
+        x += residual
+    if STORE_RESIDUAL_OUT:
+        tl.store(RESIDUAL_OUT + cols, x, mask=cols < N)
+    if not IS_RMS_NORM:
+        mean = tl.sum(x, axis=0) / N
+        tl.store(Mean + row, mean)
+        xbar = tl.where(cols < N, x - mean, 0.0)
+        var = tl.sum(xbar * xbar, axis=0) / N
+    else:
+        xbar = tl.where(cols < N, x, 0.0)
+        var = tl.sum(xbar * xbar, axis=0) / N
+    rstd = 1 / tl.sqrt(var + eps)
+    tl.store(Rstd + row, rstd)
+    # Normalize and apply linear transformation
+    mask = cols < N
+    w = tl.load(W + cols, mask=mask).to(tl.float32)
+    if HAS_BIAS:
+        b = tl.load(B + cols, mask=mask).to(tl.float32)
+    x_hat = (x - mean) * rstd if not IS_RMS_NORM else x * rstd
+    y = x_hat * w + b if HAS_BIAS else x_hat * w
+    # Write output
+    tl.store(Y + cols, y, mask=mask)
+
+
+def _layer_norm_fwd(
+    x, weight, bias, eps, residual=None, out_dtype=None, residual_dtype=None, is_rms_norm=False
+):
+    if residual is not None:
+        residual_dtype = residual.dtype
+    M, N = x.shape
+    assert x.stride(-1) == 1
+    if residual is not None:
+        assert residual.stride(-1) == 1
+        assert residual.shape == (M, N)
+    assert weight.shape == (N,)
+    assert weight.stride(-1) == 1
+    if bias is not None:
+        assert bias.stride(-1) == 1
+        assert bias.shape == (N,)
+    # allocate output
+    y = torch.empty_like(x, dtype=x.dtype if out_dtype is None else out_dtype)
+    assert y.stride(-1) == 1
+    if residual is not None or (residual_dtype is not None and residual_dtype != x.dtype):
+        residual_out = torch.empty(M, N, device=x.device, dtype=residual_dtype)
+        assert residual_out.stride(-1) == 1
+    else:
+        residual_out = None
+    mean = torch.empty((M,), dtype=torch.float32, device="cuda") if not is_rms_norm else None
+    rstd = torch.empty((M,), dtype=torch.float32, device="cuda")
+    # Less than 64KB per feature: enqueue fused kernel
+    MAX_FUSED_SIZE = 65536 // x.element_size()
+    BLOCK_N = min(MAX_FUSED_SIZE, triton.next_power_of_2(N))
+    if N > BLOCK_N:
+        raise RuntimeError("This layer norm doesn't support feature dim >= 64KB.")
+    # heuristics for number of warps
+    with torch.cuda.device(x.device.index):
+        _layer_norm_fwd_1pass_kernel[(M,)](
+            x,
+            y,
+            weight,
+            bias,
+            residual,
+            residual_out,
+            mean,
+            rstd,
+            x.stride(0),
+            y.stride(0),
+            residual.stride(0) if residual is not None else 0,
+            residual_out.stride(0) if residual_out is not None else 0,
+            N,
+            eps,
+            is_rms_norm,
+            BLOCK_N,
+            residual is not None,
+            residual_out is not None,
+            bias is not None,
+        )
+    # residual_out is None if residual is None and residual_dtype == input_dtype
+    return y, mean, rstd, residual_out if residual_out is not None else x
+
+
+@triton.autotune(
+    configs=[
+        triton.Config({}, num_warps=1),
+        triton.Config({}, num_warps=2),
+        triton.Config({}, num_warps=4),
+        triton.Config({}, num_warps=8),
+        triton.Config({}, num_warps=16),
+        triton.Config({}, num_warps=32),
+    ],
+    key=["N", "HAS_DRESIDUAL", "STORE_DRESIDUAL", "IS_RMS_NORM", "HAS_BIAS"],
+)
+# @triton.heuristics({"HAS_BIAS": lambda args: args["B"] is not None})
+# @triton.heuristics({"HAS_DRESIDUAL": lambda args: args["DRESIDUAL"] is not None})
+# @triton.heuristics({"STORE_DRESIDUAL": lambda args: args["DRESIDUAL_IN"] is not None})
+@triton.heuristics({"RECOMPUTE_OUTPUT": lambda args: args["Y"] is not None})
+@triton.jit
+def _layer_norm_bwd_kernel(
+    X,  # pointer to the input
+    W,  # pointer to the weights
+    B,  # pointer to the biases
+    Y,  # pointer to the output to be recomputed
+    DY,  # pointer to the output gradient
+    DX,  # pointer to the input gradient
+    DW,  # pointer to the partial sum of weights gradient
+    DB,  # pointer to the partial sum of biases gradient
+    DRESIDUAL,
+    DRESIDUAL_IN,
+    Mean,  # pointer to the mean
+    Rstd,  # pointer to the 1/std
+    stride_x_row,  # how much to increase the pointer when moving by 1 row
+    stride_y_row,
+    stride_dy_row,
+    stride_dx_row,
+    stride_dres_row,
+    stride_dres_in_row,
+    M,  # number of rows in X
+    N,  # number of columns in X
+    eps,  # epsilon to avoid division by zero
+    rows_per_program,
+    IS_RMS_NORM: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    HAS_DRESIDUAL: tl.constexpr,
+    STORE_DRESIDUAL: tl.constexpr,
+    HAS_BIAS: tl.constexpr,
+    RECOMPUTE_OUTPUT: tl.constexpr,
+):
+    # Map the program id to the elements of X, DX, and DY it should compute.
+    row_block_id = tl.program_id(0)
+    row_start = row_block_id * rows_per_program
+    cols = tl.arange(0, BLOCK_N)
+    mask = cols < N
+    X += row_start * stride_x_row
+    if HAS_DRESIDUAL:
+        DRESIDUAL += row_start * stride_dres_row
+    if STORE_DRESIDUAL:
+        DRESIDUAL_IN += row_start * stride_dres_in_row
+    DY += row_start * stride_dy_row
+    DX += row_start * stride_dx_row
+    if RECOMPUTE_OUTPUT:
+        Y += row_start * stride_y_row
+    w = tl.load(W + cols, mask=mask).to(tl.float32)
+    if RECOMPUTE_OUTPUT and HAS_BIAS:
+        b = tl.load(B + cols, mask=mask, other=0.0).to(tl.float32)
+    dw = tl.zeros((BLOCK_N,), dtype=tl.float32)
+    if HAS_BIAS:
+        db = tl.zeros((BLOCK_N,), dtype=tl.float32)
+    row_end = min((row_block_id + 1) * rows_per_program, M)
+    for row in range(row_start, row_end):
+        # Load data to SRAM
+        x = tl.load(X + cols, mask=mask, other=0).to(tl.float32)
+        dy = tl.load(DY + cols, mask=mask, other=0).to(tl.float32)
+        if not IS_RMS_NORM:
+            mean = tl.load(Mean + row)
+        rstd = tl.load(Rstd + row)
+        # Compute dx
+        xhat = (x - mean) * rstd if not IS_RMS_NORM else x * rstd
+        xhat = tl.where(mask, xhat, 0.0)
+        if RECOMPUTE_OUTPUT:
+            y = xhat * w + b if HAS_BIAS else xhat * w
+            tl.store(Y + cols, y, mask=mask)
+        wdy = w * dy
+        dw += dy * xhat
+        if HAS_BIAS:
+            db += dy
+        if not IS_RMS_NORM:
+            c1 = tl.sum(xhat * wdy, axis=0) / N
+            c2 = tl.sum(wdy, axis=0) / N
+            dx = (wdy - (xhat * c1 + c2)) * rstd
+        else:
+            c1 = tl.sum(xhat * wdy, axis=0) / N
+            dx = (wdy - xhat * c1) * rstd
+        if HAS_DRESIDUAL:
+            dres = tl.load(DRESIDUAL + cols, mask=mask, other=0).to(tl.float32)
+            dx += dres
+        # Write dx
+        if STORE_DRESIDUAL:
+            tl.store(DRESIDUAL_IN + cols, dx, mask=mask)
+        tl.store(DX + cols, dx, mask=mask)
+
+        X += stride_x_row
+        if HAS_DRESIDUAL:
+            DRESIDUAL += stride_dres_row
+        if STORE_DRESIDUAL:
+            DRESIDUAL_IN += stride_dres_in_row
+        if RECOMPUTE_OUTPUT:
+            Y += stride_y_row
+        DY += stride_dy_row
+        DX += stride_dx_row
+    tl.store(DW + row_block_id * N + cols, dw, mask=mask)
+    if HAS_BIAS:
+        tl.store(DB + row_block_id * N + cols, db, mask=mask)
+
+
+def _layer_norm_bwd(
+    dy,
+    x,
+    weight,
+    bias,
+    eps,
+    mean,
+    rstd,
+    dresidual=None,
+    has_residual=False,
+    is_rms_norm=False,
+    x_dtype=None,
+    recompute_output=False,
+):
+    M, N = x.shape
+    assert x.stride(-1) == 1
+    assert dy.stride(-1) == 1
+    assert dy.shape == (M, N)
+    if dresidual is not None:
+        assert dresidual.stride(-1) == 1
+        assert dresidual.shape == (M, N)
+    assert weight.shape == (N,)
+    assert weight.stride(-1) == 1
+    if bias is not None:
+        assert bias.stride(-1) == 1
+        assert bias.shape == (N,)
+    # allocate output
+    dx = (
+        torch.empty_like(x)
+        if x_dtype is None
+        else torch.empty(M, N, dtype=x_dtype, device=x.device)
+    )
+    dresidual_in = torch.empty_like(x) if has_residual and dx.dtype != x.dtype else None
+    y = torch.empty(M, N, dtype=dy.dtype, device=dy.device) if recompute_output else None
+
+    # Less than 64KB per feature: enqueue fused kernel
+    MAX_FUSED_SIZE = 65536 // x.element_size()
+    BLOCK_N = min(MAX_FUSED_SIZE, triton.next_power_of_2(N))
+    if N > BLOCK_N:
+        raise RuntimeError("This layer norm doesn't support feature dim >= 64KB.")
+    sm_count = torch.cuda.get_device_properties(x.device).multi_processor_count
+    _dw = torch.empty((sm_count, N), dtype=torch.float32, device=weight.device)
+    _db = (
+        torch.empty((sm_count, N), dtype=torch.float32, device=bias.device)
+        if bias is not None
+        else None
+    )
+    rows_per_program = math.ceil(M / sm_count)
+    grid = (sm_count,)
+    with torch.cuda.device(x.device.index):
+        _layer_norm_bwd_kernel[grid](
+            x,
+            weight,
+            bias,
+            y,
+            dy,
+            dx,
+            _dw,
+            _db,
+            dresidual,
+            dresidual_in,
+            mean,
+            rstd,
+            x.stride(0),
+            0 if not recompute_output else y.stride(0),
+            dy.stride(0),
+            dx.stride(0),
+            dresidual.stride(0) if dresidual is not None else 0,
+            dresidual_in.stride(0) if dresidual_in is not None else 0,
+            M,
+            N,
+            eps,
+            rows_per_program,
+            is_rms_norm,
+            BLOCK_N,
+            dresidual is not None,
+            dresidual_in is not None,
+            bias is not None,
+        )
+    dw = _dw.sum(0).to(weight.dtype)
+    db = _db.sum(0).to(bias.dtype) if bias is not None else None
+    # Don't need to compute dresidual_in separately in this case
+    if has_residual and dx.dtype == x.dtype:
+        dresidual_in = dx
+    return (dx, dw, db, dresidual_in) if not recompute_output else (dx, dw, db, dresidual_in, y)
+
+
+class LayerNormFn(torch.autograd.Function):
+    @staticmethod
+    def forward(
+        ctx,
+        x,
+        weight,
+        bias,
+        residual=None,
+        eps=1e-6,
+        prenorm=False,
+        residual_in_fp32=False,
+        is_rms_norm=False,
+    ):
+        x_shape_og = x.shape
+        # reshape input data into 2D tensor
+        x = x.reshape(-1, x.shape[-1])
+        if x.stride(-1) != 1:
+            x = x.contiguous()
+        if residual is not None:
+            assert residual.shape == x_shape_og
+            residual = residual.reshape(-1, residual.shape[-1])
+            if residual.stride(-1) != 1:
+                residual = residual.contiguous()
+        weight = weight.contiguous()
+        if bias is not None:
+            bias = bias.contiguous()
+        residual_dtype = (
+            residual.dtype
+            if residual is not None
+            else (torch.float32 if residual_in_fp32 else None)
+        )
+        y, mean, rstd, residual_out = _layer_norm_fwd(
+            x, weight, bias, eps, residual, residual_dtype=residual_dtype, is_rms_norm=is_rms_norm
+        )
+        ctx.save_for_backward(residual_out, weight, bias, mean, rstd)
+        ctx.x_shape_og = x_shape_og
+        ctx.eps = eps
+        ctx.is_rms_norm = is_rms_norm
+        ctx.has_residual = residual is not None
+        ctx.prenorm = prenorm
+        ctx.x_dtype = x.dtype
+        y = y.reshape(x_shape_og)
+        return y if not prenorm else (y, residual_out.reshape(x_shape_og))
+
+    @staticmethod
+    def backward(ctx, dy, *args):
+        x, weight, bias, mean, rstd = ctx.saved_tensors
+        dy = dy.reshape(-1, dy.shape[-1])
+        if dy.stride(-1) != 1:
+            dy = dy.contiguous()
+        assert dy.shape == x.shape
+        if ctx.prenorm:
+            dresidual = args[0]
+            dresidual = dresidual.reshape(-1, dresidual.shape[-1])
+            if dresidual.stride(-1) != 1:
+                dresidual = dresidual.contiguous()
+            assert dresidual.shape == x.shape
+        else:
+            dresidual = None
+        dx, dw, db, dresidual_in = _layer_norm_bwd(
+            dy,
+            x,
+            weight,
+            bias,
+            ctx.eps,
+            mean,
+            rstd,
+            dresidual,
+            ctx.has_residual,
+            ctx.is_rms_norm,
+            x_dtype=ctx.x_dtype,
+        )
+        return (
+            dx.reshape(ctx.x_shape_og),
+            dw,
+            db,
+            dresidual_in.reshape(ctx.x_shape_og) if ctx.has_residual else None,
+            None,
+            None,
+            None,
+            None,
+        )
+
+
+def layer_norm_fn(
+    x,
+    weight,
+    bias,
+    residual=None,
+    eps=1e-6,
+    prenorm=False,
+    residual_in_fp32=False,
+    is_rms_norm=False,
+):
+    return LayerNormFn.apply(x, weight, bias, residual, eps, prenorm, residual_in_fp32, is_rms_norm)
+
+
+def rms_norm_fn(x, weight, bias, residual=None, prenorm=False, residual_in_fp32=False, eps=1e-6):
+    return LayerNormFn.apply(x, weight, bias, residual, eps, prenorm, residual_in_fp32, True)
+
+
+class RMSNorm(torch.nn.Module):
+    def __init__(self, hidden_size, eps=1e-5, device=None, dtype=None):
+        factory_kwargs = {"device": device, "dtype": dtype}
+        super().__init__()
+        self.eps = eps
+        self.weight = torch.nn.Parameter(torch.empty(hidden_size, **factory_kwargs))
+        self.register_parameter("bias", None)
+        self.reset_parameters()
+
+    def reset_parameters(self):
+        torch.nn.init.ones_(self.weight)
+
+    def forward(self, x, residual=None, prenorm=False, residual_in_fp32=False):
+        return rms_norm_fn(
+            x,
+            self.weight,
+            self.bias,
+            residual=residual,
+            eps=self.eps,
+            prenorm=prenorm,
+            residual_in_fp32=residual_in_fp32,
+            # is_rms_norm=True,
+        )
+
+
+class LayerNormLinearFn(torch.autograd.Function):
+    @staticmethod
+    @custom_fwd
+    def forward(
+        ctx,
+        x,
+        norm_weight,
+        norm_bias,
+        linear_weight,
+        linear_bias,
+        residual=None,
+        eps=1e-6,
+        prenorm=False,
+        residual_in_fp32=False,
+        is_rms_norm=False,
+    ):
+        x_shape_og = x.shape
+        # reshape input data into 2D tensor
+        x = x.reshape(-1, x.shape[-1])
+        if x.stride(-1) != 1:
+            x = x.contiguous()
+        if residual is not None:
+            assert residual.shape == x_shape_og
+            residual = residual.reshape(-1, residual.shape[-1])
+            if residual.stride(-1) != 1:
+                residual = residual.contiguous()
+        norm_weight = norm_weight.contiguous()
+        if norm_bias is not None:
+            norm_bias = norm_bias.contiguous()
+        residual_dtype = (
+            residual.dtype
+            if residual is not None
+            else (torch.float32 if residual_in_fp32 else None)
+        )
+        y, mean, rstd, residual_out = _layer_norm_fwd(
+            x,
+            norm_weight,
+            norm_bias,
+            eps,
+            residual,
+            out_dtype=None if not torch.is_autocast_enabled() else torch.get_autocast_gpu_dtype(),
+            residual_dtype=residual_dtype,
+            is_rms_norm=is_rms_norm,
+        )
+        y = y.reshape(x_shape_og)
+        dtype = torch.get_autocast_gpu_dtype() if torch.is_autocast_enabled() else y.dtype
+        linear_weight = linear_weight.to(dtype)
+        linear_bias = linear_bias.to(dtype) if linear_bias is not None else None
+        out = F.linear(y.to(linear_weight.dtype), linear_weight, linear_bias)
+        # We don't store y, will be recomputed in the backward pass to save memory
+        ctx.save_for_backward(residual_out, norm_weight, norm_bias, linear_weight, mean, rstd)
+        ctx.x_shape_og = x_shape_og
+        ctx.eps = eps
+        ctx.is_rms_norm = is_rms_norm
+        ctx.has_residual = residual is not None
+        ctx.prenorm = prenorm
+        ctx.x_dtype = x.dtype
+        ctx.linear_bias_is_none = linear_bias is None
+        return out if not prenorm else (out, residual_out.reshape(x_shape_og))
+
+    @staticmethod
+    @custom_bwd
+    def backward(ctx, dout, *args):
+        x, norm_weight, norm_bias, linear_weight, mean, rstd = ctx.saved_tensors
+        dout = dout.reshape(-1, dout.shape[-1])
+        dy = F.linear(dout, linear_weight.t())
+        dlinear_bias = None if ctx.linear_bias_is_none else dout.sum(0)
+        if dy.stride(-1) != 1:
+            dy = dy.contiguous()
+        assert dy.shape == x.shape
+        if ctx.prenorm:
+            dresidual = args[0]
+            dresidual = dresidual.reshape(-1, dresidual.shape[-1])
+            if dresidual.stride(-1) != 1:
+                dresidual = dresidual.contiguous()
+            assert dresidual.shape == x.shape
+        else:
+            dresidual = None
+        dx, dnorm_weight, dnorm_bias, dresidual_in, y = _layer_norm_bwd(
+            dy,
+            x,
+            norm_weight,
+            norm_bias,
+            ctx.eps,
+            mean,
+            rstd,
+            dresidual,
+            ctx.has_residual,
+            ctx.is_rms_norm,
+            x_dtype=ctx.x_dtype,
+            recompute_output=True,
+        )
+        dlinear_weight = torch.einsum("bo,bi->oi", dout, y)
+        return (
+            dx.reshape(ctx.x_shape_og),
+            dnorm_weight,
+            dnorm_bias,
+            dlinear_weight,
+            dlinear_bias,
+            dresidual_in.reshape(ctx.x_shape_og) if ctx.has_residual else None,
+            None,
+            None,
+            None,
+            None,
+        )
+
+
+def layer_norm_linear_fn(
+    x,
+    norm_weight,
+    norm_bias,
+    linear_weight,
+    linear_bias,
+    residual=None,
+    eps=1e-6,
+    prenorm=False,
+    residual_in_fp32=False,
+    is_rms_norm=False,
+):
+    return LayerNormLinearFn.apply(
+        x,
+        norm_weight,
+        norm_bias,
+        linear_weight,
+        linear_bias,
+        residual,
+        eps,
+        prenorm,
+        residual_in_fp32,
+        is_rms_norm,
+    )