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#!/usr/bin/env python3 | |
# -*- coding:utf-8 -*- | |
# Copyright (c) 2014-2021 Megvii Inc. All rights reserved. | |
import torch | |
import torch.nn as nn | |
from thop import profile | |
from copy import deepcopy | |
__all__ = [ | |
"fuse_conv_and_bn", | |
"fuse_model", | |
"get_model_info", | |
"replace_module", | |
] | |
def get_model_info(model, tsize): | |
stride = 64 | |
img = torch.zeros((1, 3, stride, stride), device=next(model.parameters()).device) | |
flops, params = profile(deepcopy(model), inputs=(img,), verbose=False) | |
params /= 1e6 | |
flops /= 1e9 | |
flops *= tsize[0] * tsize[1] / stride / stride * 2 # Gflops | |
info = "Params: {:.2f}M, Gflops: {:.2f}".format(params, flops) | |
return info | |
def fuse_conv_and_bn(conv, bn): | |
# Fuse convolution and batchnorm layers https://tehnokv.com/posts/fusing-batchnorm-and-conv/ | |
fusedconv = ( | |
nn.Conv2d( | |
conv.in_channels, | |
conv.out_channels, | |
kernel_size=conv.kernel_size, | |
stride=conv.stride, | |
padding=conv.padding, | |
groups=conv.groups, | |
bias=True, | |
) | |
.requires_grad_(False) | |
.to(conv.weight.device) | |
) | |
# prepare filters | |
w_conv = conv.weight.clone().view(conv.out_channels, -1) | |
w_bn = torch.diag(bn.weight.div(torch.sqrt(bn.eps + bn.running_var))) | |
fusedconv.weight.copy_(torch.mm(w_bn, w_conv).view(fusedconv.weight.shape)) | |
# prepare spatial bias | |
b_conv = ( | |
torch.zeros(conv.weight.size(0), device=conv.weight.device) | |
if conv.bias is None | |
else conv.bias | |
) | |
b_bn = bn.bias - bn.weight.mul(bn.running_mean).div( | |
torch.sqrt(bn.running_var + bn.eps) | |
) | |
fusedconv.bias.copy_(torch.mm(w_bn, b_conv.reshape(-1, 1)).reshape(-1) + b_bn) | |
return fusedconv | |
def fuse_model(model): | |
from yolox.models.network_blocks import BaseConv | |
for m in model.modules(): | |
if type(m) is BaseConv and hasattr(m, "bn"): | |
m.conv = fuse_conv_and_bn(m.conv, m.bn) # update conv | |
delattr(m, "bn") # remove batchnorm | |
m.forward = m.fuseforward # update forward | |
return model | |
def replace_module(module, replaced_module_type, new_module_type, replace_func=None): | |
""" | |
Replace given type in module to a new type. mostly used in deploy. | |
Args: | |
module (nn.Module): model to apply replace operation. | |
replaced_module_type (Type): module type to be replaced. | |
new_module_type (Type) | |
replace_func (function): python function to describe replace logic. Defalut value None. | |
Returns: | |
model (nn.Module): module that already been replaced. | |
""" | |
def default_replace_func(replaced_module_type, new_module_type): | |
return new_module_type() | |
if replace_func is None: | |
replace_func = default_replace_func | |
model = module | |
if isinstance(module, replaced_module_type): | |
model = replace_func(replaced_module_type, new_module_type) | |
else: # recurrsively replace | |
for name, child in module.named_children(): | |
new_child = replace_module(child, replaced_module_type, new_module_type) | |
if new_child is not child: # child is already replaced | |
model.add_module(name, new_child) | |
return model | |