PyTorch模型转TensorRT

import pycuda.autoinit

import pycuda.driver as cuda

import tensorrt as trt

import torch

import time

from PIL import Image

import cv2,os

import torchvision

import numpy as np

from scipy.special import softmax

### get_img_np_nchw h和postprocess_the_output函数根据需要进行修改

TRT_LOGGER = trt.Logger()

def get_img_np_nchw(img_path):

img = Image.open(img_path).convert('L')

img = np.asarray(img, dtype='float32')

img = cv2.resize(np.array(img),(224, 224), interpolation = cv2.INTER_CUBIC)

img = img / 255.

img = img[np.newaxis, np.newaxis]

return image

class HostDeviceMem(object):

    def __init__(self, host_mem, device_mem):

        """host_mom指代cpu内存，device_mem指代GPU内存

        """

        self.host = host_mem

        self.device = device_mem

    def __str__(self):

        return "Host:\n" + str(self.host) + "\nDevice:\n" + str(self.device)

    def __repr__(self):

        return self.__str__()

def allocate_buffers(engine):

    inputs = []

    outputs = []

    bindings = []

    stream = cuda.Stream()

    for binding in engine:

        size = trt.volume(engine.get_binding_shape(binding)) * engine.max_batch_size

        dtype = trt.nptype(engine.get_binding_dtype(binding))

        # Allocate host and device buffers

        host_mem = cuda.pagelocked_empty(size, dtype)

        device_mem = cuda.mem_alloc(host_mem.nbytes)

        # Append the device buffer to device bindings.

        bindings.append(int(device_mem))

        # Append to the appropriate list.

        if engine.binding_is_input(binding):

            inputs.append(HostDeviceMem(host_mem, device_mem))

        else:

            outputs.append(HostDeviceMem(host_mem, device_mem))

    return inputs, outputs, bindings, stream

def get_engine(max_batch_size=1, onnx_file_path="", engine_file_path="",fp16_mode=False, int8_mode=False,save_engine=False):

    """

    params max_batch_size:      预先指定大小好分配显存

    params onnx_file_path:      onnx文件路径

    params engine_file_path:    待保存的序列化的引擎文件路径

    params fp16_mode:           是否采用FP16

    params int8_mode:           是否采用INT8

    params save_engine:         是否保存引擎

    returns:                    ICudaEngine

    """

    # 如果已经存在序列化之后的引擎，则直接反序列化得到cudaEngine

    if os.path.exists(engine_file_path):

        print("Reading engine from file: {}".format(engine_file_path))

        with open(engine_file_path, 'rb') as f, \

            trt.Runtime(TRT_LOGGER) as runtime:

            return runtime.deserialize_cuda_engine(f.read())  # 反序列化

    else:  # 由onnx创建cudaEngine

        # 使用logger创建一个builder

        # builder创建一个计算图 INetworkDefinition

        explicit_batch = 1 << (int)(trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH)

        # In TensorRT 7.0, the ONNX parser only supports full-dimensions mode, meaning that your network definition must be created with the explicitBatch flag set. For more information, see Working With Dynamic Shapes.

        with trt.Builder(TRT_LOGGER) as builder, \

            builder.create_network(explicit_batch) as network,  \

            trt.OnnxParser(network, TRT_LOGGER) as parser, \

            builder.create_builder_config() as config: # 使用onnx的解析器绑定计算图，后续将通过解析填充计算图

            profile = builder.create_optimization_profile()

            profile.set_shape("inputs", (1, 1, 224, 224),(1,1,224,224),(1,1,224,224))

            config.add_optimization_profile(profile)

            config.max_workspace_size = 1<<30  # 预先分配的工作空间大小,即ICudaEngine执行时GPU最大需要的空间

            builder.max_batch_size = max_batch_size # 执行时最大可以使用的batchsize

            builder.fp16_mode = fp16_mode

            builder.int8_mode = int8_mode

            if int8_mode:

                # To be updated

                raise NotImplementedError

            # 解析onnx文件，填充计算图

            if not os.path.exists(onnx_file_path):

                quit("ONNX file {} not found!".format(onnx_file_path))

            print('loading onnx file from path {} ...'.format(onnx_file_path))

            # with open(onnx_file_path, 'rb') as model: # 二值化的网络结果和参数

            #     print("Begining onnx file parsing")

            #     parser.parse(model.read())  # 解析onnx文件

            parser.parse_from_file(onnx_file_path) # parser还有一个从文件解析onnx的方法

            print("Completed parsing of onnx file")

            # 填充计算图完成后，则使用builder从计算图中创建CudaEngine

            print("Building an engine from file{}' this may take a while...".format(onnx_file_path))

            #################

            # import pdb;pdb.set_trace()

            print(network.get_layer(network.num_layers-1).get_output(0).shape)

            # network.mark_output(network.get_layer(network.num_layers -1).get_output(0))

            engine = builder.build_engine(network,config)  # 注意，这里的network是INetworkDefinition类型，即填充后的计算图

            print("Completed creating Engine")

            if save_engine:  #保存engine供以后直接反序列化使用

                with open(engine_file_path, 'wb') as f:

                    f.write(engine.serialize())  # 序列化

            return engine

def do_inference(context, bindings, inputs, outputs, stream, batch_size=1):

    # Transfer data from CPU to the GPU.

    [cuda.memcpy_htod_async(inp.device, inp.host, stream) for inp in inputs]

    # Run inference.

    context.execute_async(batch_size=batch_size, bindings=bindings, stream_handle=stream.handle)

    # Transfer predictions back from the GPU.

    [cuda.memcpy_dtoh_async(out.host, out.device, stream) for out in outputs]

    # Synchronize the stream

    stream.synchronize()

    # Return only the host outputs.

    return [out.host for out in outputs]

def postprocess_the_outputs(outputs, shape_of_output):

    outputs = outputs.reshape(*shape_of_output)

    out = np.argmax(softmax(outputs,axis=1)[0,...],axis=0)

    # import pdb;pdb.set_trace()

    return out

# 验证TensorRT模型是否正确

onnx_model_path = './Net.onnx'

max_batch_size = 1

# These two modes are dependent on hardwares

fp16_mode = False

int8_mode = False

trt_engine_path = './model_fp16_{}_int8_{}.trt'.format(fp16_mode, int8_mode)

# Build an engine

engine = get_engine(max_batch_size, onnx_model_path, trt_engine_path, fp16_mode, int8_mode , save_engine=True)

# Create the context for this engine

context = engine.create_execution_context()

# Allocate buffers for input and output

inputs, outputs, bindings, stream = allocate_buffers(engine)  # input, output: host # bindings

# Do inference

img_np_nchw = get_img_np_nchw(img_path)

inputs[0].host = img_np_nchw.reshape(-1)

shape_of_output = (max_batch_size, 2, 224, 224)

# inputs[1].host = ... for multiple input

t1 = time.time()

trt_outputs = do_inference(context, bindings=bindings, inputs=inputs, outputs=outputs, stream=stream) # numpy data

t2 = time.time()

feat = postprocess_the_outputs(trt_outputs[0], shape_of_output)

print('TensorRT ok')

print("Inference time with the TensorRT engine: {}".format(t2-t1))