sglang/sgl-kernel/python/sgl_kernel/moe.py

from typing import Optional

import torch


def moe_align_block_size(
    topk_ids,
    num_experts,
    block_size,
    sorted_token_ids,
    experts_ids,
    num_tokens_post_pad,
    cumsum_buffer,
    pad_sorted_token_ids=False,
):
    torch.ops.sgl_kernel.moe_align_block_size.default(
        topk_ids,
        num_experts,
        block_size,
        sorted_token_ids,
        experts_ids,
        num_tokens_post_pad,
        cumsum_buffer,
        pad_sorted_token_ids,
    )


def topk_softmax(
    topk_weights: torch.Tensor,
    topk_ids: torch.Tensor,
    gating_output: torch.Tensor,
    renormalize: bool = False,
    moe_softcapping: float = 0.0,
    correction_bias: Optional[torch.Tensor] = None,
) -> None:
    """
    Compute top-k softmax for MoE routing.

    Args:
        topk_weights: Output tensor for top-k weights [num_tokens, topk]
        topk_ids: Output tensor for top-k expert indices [num_tokens, topk]
        gating_output: Gating logits [num_tokens, num_experts]
        renormalize: Whether to renormalize the top-k weights
        moe_softcapping: Tanh softcapping value (0.0 to disable)
        correction_bias: Per-expert bias correction [num_experts], must be float32 if provided
    """
    torch.ops.sgl_kernel.topk_softmax.default(
        topk_weights,
        topk_ids,
        gating_output,
        renormalize,
        moe_softcapping,
        correction_bias,
    )


def topk_sigmoid(
    topk_weights: torch.Tensor,
    topk_ids: torch.Tensor,
    gating_output: torch.Tensor,
    renormalize: bool = False,
    correction_bias: Optional[torch.Tensor] = None,
) -> None:
    """
    Compute top-k sigmoid for MoE routing.

    Args:
        topk_weights: Output tensor for top-k weights [num_tokens, topk]
        topk_ids: Output tensor for top-k expert indices [num_tokens, topk]
        gating_output: Gating logits [num_tokens, num_experts]
        renormalize: Whether to renormalize the top-k weights
        correction_bias: Per-expert bias correction [num_experts], must be float32 if provided
    """
    torch.ops.sgl_kernel.topk_sigmoid.default(
        topk_weights,
        topk_ids,
        gating_output,
        renormalize,
        correction_bias,
    )


def moe_sum_reduce(
    input_tensor,
    output_tensor,
    routed_scaling_factor=0,
):
    torch.ops.sgl_kernel.moe_sum_reduce.default(
        input_tensor,
        output_tensor,
        routed_scaling_factor,
    )


def moe_sum(
    input_tensor: torch.Tensor,
    output_tensor: torch.Tensor,
):
    torch.ops.sgl_kernel.moe_sum.default(
        input_tensor,
        output_tensor,
    )


def moe_fused_gate(
    input_tensor,
    bias,
    num_expert_group,
    topk_group,
    topk,
    num_fused_shared_experts=0,
    routed_scaling_factor=0,
    apply_routed_scaling_factor_on_output=False,
):
    # This fused kernel function is used to select topk expert in a hierarchical 2-layer fashion
    # it split group of expert into num_expert_group, and use top2 expert weight sum in each group
    # as the group weight to select expert groups and then select topk experts within the selected groups
    # the #experts is decided by the input tensor shape and we currently only support power of 2 #experts
    # and #experts should be divisible by num_expert_group. #expert/num_expert_group <= 32 is limited for now.
    # for non-supported case, we suggest to use the biased_grouped_topk func in sglang.srt.layers.moe.topk
    # num_fused_shared_experts: if > 0, the last several experts will be
    #   replaced with shared experts. the shared experts will be divided by the
    #   routed_scaling_factor - this is intended to cancel out later when routed+shared
    #   output is scaled so that shared experts are not scaled.
    # routed_scaling_factor: if > 0, the experts will be scaled by this factor
    # apply_routed_scaling_factor_on_output: if true, output will be
    #   scaled by the routed_scaling_factor
    return torch.ops.sgl_kernel.moe_fused_gate.default(
        input_tensor,
        bias,
        num_expert_group,
        topk_group,
        topk,
        num_fused_shared_experts,
        routed_scaling_factor,
        apply_routed_scaling_factor_on_output,
    )


def kimi_k2_moe_fused_gate(
    input_tensor,
    bias,
    topk,
    renormalize=True,
    routed_scaling_factor=1.0,
    apply_routed_scaling_factor_on_output=False,
):
    """
    Simplified fused kernel for Kimi K2 model (num_expert_group=1).
    This kernel removes the grouped topk logic since all experts belong to a single group.

    Args:
        input_tensor: Gating output tensor [num_tokens, num_experts]
        bias: Correction bias tensor [num_experts]
        topk: Number of experts to select per token
        renormalize: Whether to renormalize the topk weights
        routed_scaling_factor: Scaling factor for expert weights
        apply_routed_scaling_factor_on_output: If true, apply scaling factor to output

    Returns:
        Tuple of (topk_weights, topk_ids)
        - topk_weights: [num_tokens, topk] float32 tensor
        - topk_ids: [num_tokens, topk] int32 tensor
    """
    return torch.ops.sgl_kernel.kimi_k2_moe_fused_gate.default(
        input_tensor,
        bias,
        topk,
        renormalize,
        routed_scaling_factor,
        apply_routed_scaling_factor_on_output,
    )


def fp8_blockwise_scaled_grouped_mm(
    output,
    a_ptrs,
    b_ptrs,
    out_ptrs,
    a_scales_ptrs,
    b_scales_ptrs,
    a,
    b,
    scales_a,
    scales_b,
    stride_a,
    stride_b,
    stride_c,
    layout_sfa,
    layout_sfb,
    problem_sizes,
    expert_offsets,
    workspace,
):
    torch.ops.sgl_kernel.fp8_blockwise_scaled_grouped_mm.default(
        output,
        a_ptrs,
        b_ptrs,
        out_ptrs,
        a_scales_ptrs,
        b_scales_ptrs,
        a,
        b,
        scales_a,
        scales_b,
        stride_a,
        stride_b,
        stride_c,
        layout_sfa,
        layout_sfb,
        problem_sizes,
        expert_offsets,
        workspace,
    )


def prepare_moe_input(
    topk_ids,
    expert_offsets,
    problem_sizes1,
    problem_sizes2,
    input_permutation,
    output_permutation,
    num_experts,
    n,
    k,
    blockscale_offsets: Optional[torch.Tensor] = None,
):
    torch.ops.sgl_kernel.prepare_moe_input.default(
        topk_ids,
        expert_offsets,
        blockscale_offsets,
        problem_sizes1,
        problem_sizes2,
        input_permutation,
        output_permutation,
        num_experts,
        n,
        k,
    )


def apply_shuffle_mul_sum(
    input,
    output,
    permutation,
    factors,
):
    torch.ops.sgl_kernel.apply_shuffle_mul_sum.default(
        input, output, permutation, factors
    )


def fused_qk_norm_rope(
    qkv: torch.Tensor,
    num_heads_q: int,
    num_heads_k: int,
    num_heads_v: int,
    head_dim: int,
    eps: float,
    q_weight: torch.Tensor,
    k_weight: torch.Tensor,
    base: float,
    is_neox: bool,
    position_ids: torch.Tensor,
    factor: float,
    low: float,
    high: float,
    attention_factor: float,
    rotary_dim: Optional[int] = None,
) -> None:
    torch.ops.sgl_kernel.fused_qk_norm_rope(
        qkv,
        num_heads_q,
        num_heads_k,
        num_heads_v,
        head_dim,
        eps,
        q_weight,
        k_weight,
        base,
        is_neox,
        position_ids,
        factor,
        low,
        high,
        attention_factor,
        rotary_dim if rotary_dim is not None else head_dim,
    )