# Model computation time measurement when using Torchscript in C++ (reposted)

**URL:** <https://discuss.pytorch.org/t/model-computation-time-measurement-when-using-torchscript-in-c-reposted/93433>\
**Category:** jit\
**Created:** [August 20, 2020, 2:33am UTC](https://discuss.pytorch.org/t/model-computation-time-measurement-when-using-torchscript-in-c-reposted/93433 "2020-08-20T02:33:04Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Jungmo\_Ahn](https://discuss.pytorch.org/letter_avatar_proxy/v4/letter/j/41988e/32.png) [@Jungmo\_Ahn](https://discuss.pytorch.org/u/Jungmo_Ahn)\
**Post date:** [August 20, 2020, 2:33am UTC](https://discuss.pytorch.org/t/model-computation-time-measurement-when-using-torchscript-in-c-reposted/93433/1 "2020-08-20T02:33:04Z")

</div>

Hello

In order to measure the computation time of the deep learning model when using GPU, we have to keep in mind about GPU operations asynchronicity. Thus, we should use torch.cuda.Event or torch.autograd.profiler in Python.

I found torch::autograd::profiler in libtorch but there is no API documentation to know how to use functions in the library. This looks like C++ version of torch.autograd.profiler which to measure model computation time. However, there are many examples to measure computation time in Python but it is hard to find any example to measure computation time when using GPU in C++.

(This might be because the majority of users except me are familiar to use C++ and C++ library. 😅)

**Could someone provide a simple example to measure computation time of Torchscript model considering both CPU time and GPU time in C++?**

FYI, in order to correctly measure computation time in Python3, please refer this link:

> [@How to measure time in PyTorch](https://discuss.pytorch.org/t/how-to-measure-time-in-pytorch/26964):
>
> I have seen lots of ways to measure time in PyTorch. But what is the most proper way to do it now (both for cpu and cuda)? Should I clear the memory cache if I use timeit? And is it possible to get accurate results if I’m computing on a cluster? And is it a way to make this results reproducible? And what is better: timeit or profiler?

Many thanks!

- I copied this question [here](https://discuss.pytorch.org/t/model-computation-time-measurement-when-using-torchscript-in-c/93218)

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<div class="post-metadata">

**Author:** ![Jungmo\_Ahn](https://discuss.pytorch.org/letter_avatar_proxy/v4/letter/j/41988e/32.png) [@Jungmo\_Ahn](https://discuss.pytorch.org/u/Jungmo_Ahn)\
**Post date:** [August 20, 2020, 1:29pm UTC](https://discuss.pytorch.org/t/model-computation-time-measurement-when-using-torchscript-in-c-reposted/93433/2 "2020-08-20T13:29:28Z")

</div>

```auto
std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
model.forward(inputs).toTensor();
cudaDeviceSynchronize(); // declared in cuda.h
std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();

```

This is my solution to measure elapsed time for model computation when using GPU.  
If there is a better way, plz suggest me.

Thanks!