Implemented flexible PP schedule (#129597)

Enabled some cases to work where num_microbatches % pp_size != 0. Using the flex_pp schedule, we will have

num_rounds = max(1, n_microbatches // pp_group_size) and it works as long as n_microbatches % num_rounds is 0. As a few examples, support

pp_group_size = 4, n_microbatches = 10. We will have num_rounds = 2 and n_microbatches % 2 is 0.
pp_group_size = 4, n_microbatches = 3. We will have num_rounds = 1 and n_microbatches % 1 is 0.

Moved over from PiPPy (https://github.com/pytorch/PiPPy/pull/1129)

Tested using the config in (1), schedule looks like the following graph:

```
=========== ALL_RANK_ACTIONS ===========
         Rank 0  Rank 1  Rank 2  Rank 3
Step 00: F0_s0   None    None    None
Step 01: F1_s0   F0_s1   None    None
Step 02: F2_s0   F1_s1   F0_s2   None
Step 03: F3_s0   F2_s1   F1_s2   F0_s3
Step 04: F4_s0   F3_s1   F2_s2   F1_s3
Step 05: F0_s4   F4_s1   F3_s2   F2_s3
Step 06: F1_s4   F0_s5   F4_s2   F3_s3
Step 07: F2_s4   F1_s5   F0_s6   F4_s3
Step 08: F3_s4   F2_s5   F1_s6   F0_s7
Step 09: F4_s4   F3_s5   None    B0_s7
Step 10: F5_s0   None    F2_s6   F1_s7
Step 11: None    None    B0_s6   B1_s7
Step 12: None    F4_s5   F3_s6   F2_s7
Step 13: None    B0_s5   B1_s6   B2_s7
Step 14: F6_s0   F5_s1   F4_s6   F3_s7
Step 15: B0_s4   B1_s5   B2_s6   B3_s7
Step 16: F7_s0   F6_s1   F5_s2   F4_s7
Step 17: B1_s4   B2_s5   B3_s6   B4_s7
Step 18: F8_s0   F7_s1   F6_s2   F5_s3
Step 19: B2_s4   B3_s5   B4_s6   B0_s3
Step 20: F9_s0   F8_s1   F7_s2   F6_s3
Step 21: B3_s4   B4_s5   B0_s2   B1_s3
Step 22: F5_s4   F9_s1   F8_s2   F7_s3
Step 23: B4_s4   B0_s1   B1_s2   B2_s3
Step 24: F6_s4   F5_s5   F9_s2   F8_s3
Step 25: B0_s0   B1_s1   B2_s2   B3_s3
Step 26: F7_s4   F6_s5   F5_s6   F9_s3
Step 27: B1_s0   B2_s1   B3_s2   B4_s3
Step 28: F8_s4   F7_s5   F6_s6   F5_s7
Step 29: B2_s0   B3_s1   B4_s2   B5_s7
Step 30: F9_s4   F8_s5   F7_s6   F6_s7
Step 31: B3_s0   B4_s1   B5_s6   B6_s7
Step 32: None    F9_s5   F8_s6   F7_s7
Step 33: B4_s0   B5_s5   B6_s6   B7_s7
Step 34: None    None    F9_s6   F8_s7
Step 35: B5_s4   B6_s5   B7_s6   B8_s7
Step 36: None    None    None    F9_s7
Step 37: B6_s4   B7_s5   B8_s6   B9_s7
Step 38: None    None    None    None
Step 39: B7_s4   B8_s5   B9_s6   B5_s3
Step 40: None    None    None    None
Step 41: B8_s4   B9_s5   B5_s2   B6_s3
Step 42: None    None    None    None
Step 43: B9_s4   B5_s1   B6_s2   B7_s3
Step 44: None    None    None    None
Step 45: B5_s0   B6_s1   B7_s2   B8_s3
Step 46: None    None    None    None
Step 47: B6_s0   B7_s1   B8_s2   B9_s3
Step 48: None    None    None
Step 49: B7_s0   B8_s1   B9_s2
Step 50: None    None
Step 51: B8_s0   B9_s1
Step 52: None
```

Pull Request resolved: https://github.com/pytorch/pytorch/pull/129597
Approved by: https://github.com/H-Huang
4 files changed
tree: 73f823c7ec9fe24946bd19277a0e373f1f5e0d7a
  1. .ci/
  2. .circleci/
  3. .ctags.d/
  4. .devcontainer/
  5. .github/
  6. .vscode/
  7. android/
  8. aten/
  9. benchmarks/
  10. binaries/
  11. c10/
  12. caffe2/
  13. cmake/
  14. docs/
  15. functorch/
  16. ios/
  17. mypy_plugins/
  18. scripts/
  19. test/
  20. third_party/
  21. tools/
  22. torch/
  23. torchgen/
  24. .bazelignore
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  26. .bazelversion
  27. .buckconfig.oss
  28. .clang-format
  29. .clang-tidy
  30. .cmakelintrc
  31. .coveragerc
  32. .flake8
  33. .gdbinit
  34. .git-blame-ignore-revs
  35. .gitattributes
  36. .gitignore
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  38. .lintrunner.toml
  39. .lldbinit
  40. aten.bzl
  41. BUCK.oss
  42. buckbuild.bzl
  43. BUILD.bazel
  44. build.bzl
  45. build_variables.bzl
  46. CITATION.cff
  47. CMakeLists.txt
  48. CODE_OF_CONDUCT.md
  49. CODEOWNERS
  50. CONTRIBUTING.md
  51. defs.bzl
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  53. Dockerfile
  54. GLOSSARY.md
  55. LICENSE
  56. Makefile
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  60. NOTICE
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  62. pt_template_srcs.bzl
  63. pyproject.toml
  64. pytest.ini
  65. README.md
  66. RELEASE.md
  67. requirements.txt
  68. SECURITY.md
  69. setup.py
  70. ubsan.supp
  71. ufunc_defs.bzl
  72. version.txt
  73. WORKSPACE
README.md

PyTorch Logo


PyTorch is a Python package that provides two high-level features:

  • Tensor computation (like NumPy) with strong GPU acceleration
  • Deep neural networks built on a tape-based autograd system

You can reuse your favorite Python packages such as NumPy, SciPy, and Cython to extend PyTorch when needed.

Our trunk health (Continuous Integration signals) can be found at hud.pytorch.org.

More About PyTorch

Learn the basics of PyTorch

At a granular level, PyTorch is a library that consists of the following components:

ComponentDescription
torchA Tensor library like NumPy, with strong GPU support
torch.autogradA tape-based automatic differentiation library that supports all differentiable Tensor operations in torch
torch.jitA compilation stack (TorchScript) to create serializable and optimizable models from PyTorch code
torch.nnA neural networks library deeply integrated with autograd designed for maximum flexibility
torch.multiprocessingPython multiprocessing, but with magical memory sharing of torch Tensors across processes. Useful for data loading and Hogwild training
torch.utilsDataLoader and other utility functions for convenience

Usually, PyTorch is used either as:

  • A replacement for NumPy to use the power of GPUs.
  • A deep learning research platform that provides maximum flexibility and speed.

Elaborating Further:

A GPU-Ready Tensor Library

If you use NumPy, then you have used Tensors (a.k.a. ndarray).

Tensor illustration

PyTorch provides Tensors that can live either on the CPU or the GPU and accelerates the computation by a huge amount.

We provide a wide variety of tensor routines to accelerate and fit your scientific computation needs such as slicing, indexing, mathematical operations, linear algebra, reductions. And they are fast!

Dynamic Neural Networks: Tape-Based Autograd

PyTorch has a unique way of building neural networks: using and replaying a tape recorder.

Most frameworks such as TensorFlow, Theano, Caffe, and CNTK have a static view of the world. One has to build a neural network and reuse the same structure again and again. Changing the way the network behaves means that one has to start from scratch.

With PyTorch, we use a technique called reverse-mode auto-differentiation, which allows you to change the way your network behaves arbitrarily with zero lag or overhead. Our inspiration comes from several research papers on this topic, as well as current and past work such as torch-autograd, autograd, Chainer, etc.

While this technique is not unique to PyTorch, it's one of the fastest implementations of it to date. You get the best of speed and flexibility for your crazy research.

Dynamic graph

Python First

PyTorch is not a Python binding into a monolithic C++ framework. It is built to be deeply integrated into Python. You can use it naturally like you would use NumPy / SciPy / scikit-learn etc. You can write your new neural network layers in Python itself, using your favorite libraries and use packages such as Cython and Numba. Our goal is to not reinvent the wheel where appropriate.

Imperative Experiences

PyTorch is designed to be intuitive, linear in thought, and easy to use. When you execute a line of code, it gets executed. There isn't an asynchronous view of the world. When you drop into a debugger or receive error messages and stack traces, understanding them is straightforward. The stack trace points to exactly where your code was defined. We hope you never spend hours debugging your code because of bad stack traces or asynchronous and opaque execution engines.

Fast and Lean

PyTorch has minimal framework overhead. We integrate acceleration libraries such as Intel MKL and NVIDIA (cuDNN, NCCL) to maximize speed. At the core, its CPU and GPU Tensor and neural network backends are mature and have been tested for years.

Hence, PyTorch is quite fast — whether you run small or large neural networks.

The memory usage in PyTorch is extremely efficient compared to Torch or some of the alternatives. We've written custom memory allocators for the GPU to make sure that your deep learning models are maximally memory efficient. This enables you to train bigger deep learning models than before.

Extensions Without Pain

Writing new neural network modules, or interfacing with PyTorch's Tensor API was designed to be straightforward and with minimal abstractions.

You can write new neural network layers in Python using the torch API or your favorite NumPy-based libraries such as SciPy.

If you want to write your layers in C/C++, we provide a convenient extension API that is efficient and with minimal boilerplate. No wrapper code needs to be written. You can see a tutorial here and an example here.

Installation

Binaries

Commands to install binaries via Conda or pip wheels are on our website: https://pytorch.org/get-started/locally/

NVIDIA Jetson Platforms

Python wheels for NVIDIA's Jetson Nano, Jetson TX1/TX2, Jetson Xavier NX/AGX, and Jetson AGX Orin are provided here and the L4T container is published here

They require JetPack 4.2 and above, and @dusty-nv and @ptrblck are maintaining them.

From Source

Prerequisites

If you are installing from source, you will need:

  • Python 3.8 or later (for Linux, Python 3.8.1+ is needed)
  • A compiler that fully supports C++17, such as clang or gcc (gcc 9.4.0 or newer is required)

We highly recommend installing an Anaconda environment. You will get a high-quality BLAS library (MKL) and you get controlled dependency versions regardless of your Linux distro.

NVIDIA CUDA Support

If you want to compile with CUDA support, select a supported version of CUDA from our support matrix, then install the following:

Note: You could refer to the cuDNN Support Matrix for cuDNN versions with the various supported CUDA, CUDA driver and NVIDIA hardware

If you want to disable CUDA support, export the environment variable USE_CUDA=0. Other potentially useful environment variables may be found in setup.py.

If you are building for NVIDIA's Jetson platforms (Jetson Nano, TX1, TX2, AGX Xavier), Instructions to install PyTorch for Jetson Nano are available here

AMD ROCm Support

If you want to compile with ROCm support, install

  • AMD ROCm 4.0 and above installation
  • ROCm is currently supported only for Linux systems.

If you want to disable ROCm support, export the environment variable USE_ROCM=0. Other potentially useful environment variables may be found in setup.py.

Intel GPU Support

If you want to compile with Intel GPU support, follow these

If you want to disable Intel GPU support, export the environment variable USE_XPU=0. Other potentially useful environment variables may be found in setup.py.

Install Dependencies

Common

conda install cmake ninja
# Run this command from the PyTorch directory after cloning the source code using the “Get the PyTorch Source“ section below
pip install -r requirements.txt

On Linux

conda install intel::mkl-static intel::mkl-include
# CUDA only: Add LAPACK support for the GPU if needed
conda install -c pytorch magma-cuda121  # or the magma-cuda* that matches your CUDA version from https://anaconda.org/pytorch/repo

# (optional) If using torch.compile with inductor/triton, install the matching version of triton
# Run from the pytorch directory after cloning
# For Intel GPU support, please explicitly `export USE_XPU=1` before running command.
make triton

On MacOS

# Add this package on intel x86 processor machines only
conda install intel::mkl-static intel::mkl-include
# Add these packages if torch.distributed is needed
conda install pkg-config libuv

On Windows

conda install intel::mkl-static intel::mkl-include
# Add these packages if torch.distributed is needed.
# Distributed package support on Windows is a prototype feature and is subject to changes.
conda install -c conda-forge libuv=1.39

Get the PyTorch Source

git clone --recursive https://github.com/pytorch/pytorch
cd pytorch
# if you are updating an existing checkout
git submodule sync
git submodule update --init --recursive

Install PyTorch

On Linux

If you would like to compile PyTorch with new C++ ABI enabled, then first run this command:

export _GLIBCXX_USE_CXX11_ABI=1

If you're compiling for AMD ROCm then first run this command:

# Only run this if you're compiling for ROCm
python tools/amd_build/build_amd.py

Install PyTorch

export CMAKE_PREFIX_PATH=${CONDA_PREFIX:-"$(dirname $(which conda))/../"}
python setup.py develop

Aside: If you are using Anaconda, you may experience an error caused by the linker:

build/temp.linux-x86_64-3.7/torch/csrc/stub.o: file not recognized: file format not recognized
collect2: error: ld returned 1 exit status
error: command 'g++' failed with exit status 1

This is caused by ld from the Conda environment shadowing the system ld. You should use a newer version of Python that fixes this issue. The recommended Python version is 3.8.1+.

On macOS

python3 setup.py develop

On Windows

Choose Correct Visual Studio Version.

PyTorch CI uses Visual C++ BuildTools, which come with Visual Studio Enterprise, Professional, or Community Editions. You can also install the build tools from https://visualstudio.microsoft.com/visual-cpp-build-tools/. The build tools do not come with Visual Studio Code by default.

If you want to build legacy python code, please refer to Building on legacy code and CUDA

CPU-only builds

In this mode PyTorch computations will run on your CPU, not your GPU

conda activate
python setup.py develop

Note on OpenMP: The desired OpenMP implementation is Intel OpenMP (iomp). In order to link against iomp, you'll need to manually download the library and set up the building environment by tweaking CMAKE_INCLUDE_PATH and LIB. The instruction here is an example for setting up both MKL and Intel OpenMP. Without these configurations for CMake, Microsoft Visual C OpenMP runtime (vcomp) will be used.

CUDA based build

In this mode PyTorch computations will leverage your GPU via CUDA for faster number crunching

NVTX is needed to build Pytorch with CUDA. NVTX is a part of CUDA distributive, where it is called “Nsight Compute”. To install it onto an already installed CUDA run CUDA installation once again and check the corresponding checkbox. Make sure that CUDA with Nsight Compute is installed after Visual Studio.

Currently, VS 2017 / 2019, and Ninja are supported as the generator of CMake. If ninja.exe is detected in PATH, then Ninja will be used as the default generator, otherwise, it will use VS 2017 / 2019.
If Ninja is selected as the generator, the latest MSVC will get selected as the underlying toolchain.

Additional libraries such as Magma, oneDNN, a.k.a. MKLDNN or DNNL, and Sccache are often needed. Please refer to the installation-helper to install them.

You can refer to the build_pytorch.bat script for some other environment variables configurations

cmd

:: Set the environment variables after you have downloaded and unzipped the mkl package,
:: else CMake would throw an error as `Could NOT find OpenMP`.
set CMAKE_INCLUDE_PATH={Your directory}\mkl\include
set LIB={Your directory}\mkl\lib;%LIB%

:: Read the content in the previous section carefully before you proceed.
:: [Optional] If you want to override the underlying toolset used by Ninja and Visual Studio with CUDA, please run the following script block.
:: "Visual Studio 2019 Developer Command Prompt" will be run automatically.
:: Make sure you have CMake >= 3.12 before you do this when you use the Visual Studio generator.
set CMAKE_GENERATOR_TOOLSET_VERSION=14.27
set DISTUTILS_USE_SDK=1
for /f "usebackq tokens=*" %i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -version [15^,17^) -products * -latest -property installationPath`) do call "%i\VC\Auxiliary\Build\vcvarsall.bat" x64 -vcvars_ver=%CMAKE_GENERATOR_TOOLSET_VERSION%

:: [Optional] If you want to override the CUDA host compiler
set CUDAHOSTCXX=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\bin\HostX64\x64\cl.exe

python setup.py develop

Adjust Build Options (Optional)

You can adjust the configuration of cmake variables optionally (without building first), by doing the following. For example, adjusting the pre-detected directories for CuDNN or BLAS can be done with such a step.

On Linux

export CMAKE_PREFIX_PATH=${CONDA_PREFIX:-"$(dirname $(which conda))/../"}
python setup.py build --cmake-only
ccmake build  # or cmake-gui build

On macOS

export CMAKE_PREFIX_PATH=${CONDA_PREFIX:-"$(dirname $(which conda))/../"}
MACOSX_DEPLOYMENT_TARGET=10.9 CC=clang CXX=clang++ python setup.py build --cmake-only
ccmake build  # or cmake-gui build

Docker Image

Using pre-built images

You can also pull a pre-built docker image from Docker Hub and run with docker v19.03+

docker run --gpus all --rm -ti --ipc=host pytorch/pytorch:latest

Please note that PyTorch uses shared memory to share data between processes, so if torch multiprocessing is used (e.g. for multithreaded data loaders) the default shared memory segment size that container runs with is not enough, and you should increase shared memory size either with --ipc=host or --shm-size command line options to nvidia-docker run.

Building the image yourself

NOTE: Must be built with a docker version > 18.06

The Dockerfile is supplied to build images with CUDA 11.1 support and cuDNN v8. You can pass PYTHON_VERSION=x.y make variable to specify which Python version is to be used by Miniconda, or leave it unset to use the default.

make -f docker.Makefile
# images are tagged as docker.io/${your_docker_username}/pytorch

You can also pass the CMAKE_VARS="..." environment variable to specify additional CMake variables to be passed to CMake during the build. See setup.py for the list of available variables.

make -f docker.Makefile

Building the Documentation

To build documentation in various formats, you will need Sphinx and the readthedocs theme.

cd docs/
pip install -r requirements.txt

You can then build the documentation by running make <format> from the docs/ folder. Run make to get a list of all available output formats.

If you get a katex error run npm install katex. If it persists, try npm install -g katex

Note: if you installed nodejs with a different package manager (e.g., conda) then npm will probably install a version of katex that is not compatible with your version of nodejs and doc builds will fail. A combination of versions that is known to work is node@6.13.1 and katex@0.13.18. To install the latter with npm you can run npm install -g katex@0.13.18

Previous Versions

Installation instructions and binaries for previous PyTorch versions may be found on our website.

Getting Started

Three-pointers to get you started:

Resources

Communication

Releases and Contributing

Typically, PyTorch has three minor releases a year. Please let us know if you encounter a bug by filing an issue.

We appreciate all contributions. If you are planning to contribute back bug-fixes, please do so without any further discussion.

If you plan to contribute new features, utility functions, or extensions to the core, please first open an issue and discuss the feature with us. Sending a PR without discussion might end up resulting in a rejected PR because we might be taking the core in a different direction than you might be aware of.

To learn more about making a contribution to Pytorch, please see our Contribution page. For more information about PyTorch releases, see Release page.

The Team

PyTorch is a community-driven project with several skillful engineers and researchers contributing to it.

PyTorch is currently maintained by Soumith Chintala, Gregory Chanan, Dmytro Dzhulgakov, Edward Yang, and Nikita Shulga with major contributions coming from hundreds of talented individuals in various forms and means. A non-exhaustive but growing list needs to mention: Trevor Killeen, Sasank Chilamkurthy, Sergey Zagoruyko, Adam Lerer, Francisco Massa, Alykhan Tejani, Luca Antiga, Alban Desmaison, Andreas Koepf, James Bradbury, Zeming Lin, Yuandong Tian, Guillaume Lample, Marat Dukhan, Natalia Gimelshein, Christian Sarofeen, Martin Raison, Edward Yang, Zachary Devito.

Note: This project is unrelated to hughperkins/pytorch with the same name. Hugh is a valuable contributor to the Torch community and has helped with many things Torch and PyTorch.

License

PyTorch has a BSD-style license, as found in the LICENSE file.