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Previously: https://github.com/pytorch/pytorch/pull/138052 but the implementation is done from scratch, so I open a new PR. This implements the ability to save and load profiles of automatic dynamic decisions, so on subsequent runs we can directly make something automatically dynamic. Unlike the previous implementation, this cache is never enabled by default; instead, you have to specify a "job id" that says it's OK to share results. We will be able to automatically populate this id for internal MAST jobs but for generic OSS users you will have to explicitly opt into it. Signed-off-by: Edward Z. Yang <ezyang@meta.com> Pull Request resolved: https://github.com/pytorch/pytorch/pull/139001 Approved by: https://github.com/oulgen
121 lines
4.6 KiB
ReStructuredText
121 lines
4.6 KiB
ReStructuredText
.. _torch.compiler_overview:
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torch.compiler
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==============
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``torch.compiler`` is a namespace through which some of the internal compiler
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methods are surfaced for user consumption. The main function and the feature in
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this namespace is ``torch.compile``.
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``torch.compile`` is a PyTorch function introduced in PyTorch 2.x that aims to
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solve the problem of accurate graph capturing in PyTorch and ultimately enable
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software engineers to run their PyTorch programs faster. ``torch.compile`` is
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written in Python and it marks the transition of PyTorch from C++ to Python.
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``torch.compile`` leverages the following underlying technologies:
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* **TorchDynamo (torch._dynamo)** is an internal API that uses a CPython
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feature called the Frame Evaluation API to safely capture PyTorch graphs.
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Methods that are available externally for PyTorch users are surfaced
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through the ``torch.compiler`` namespace.
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* **TorchInductor** is the default ``torch.compile`` deep learning compiler
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that generates fast code for multiple accelerators and backends. You
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need to use a backend compiler to make speedups through ``torch.compile``
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possible. For NVIDIA, AMD and Intel GPUs, it leverages OpenAI Triton as the key
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building block.
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* **AOT Autograd** captures not only the user-level code, but also backpropagation,
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which results in capturing the backwards pass "ahead-of-time". This enables
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acceleration of both forwards and backwards pass using TorchInductor.
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.. note:: In some cases, the terms ``torch.compile``, TorchDynamo, ``torch.compiler``
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might be used interchangeably in this documentation.
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As mentioned above, to run your workflows faster, ``torch.compile`` through
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TorchDynamo requires a backend that converts the captured graphs into a fast
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machine code. Different backends can result in various optimization gains.
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The default backend is called TorchInductor, also known as *inductor*,
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TorchDynamo has a list of supported backends developed by our partners,
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which can be see by running ``torch.compiler.list_backends()`` each of which
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with its optional dependencies.
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Some of the most commonly used backends include:
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**Training & inference backends**
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.. list-table::
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:widths: 50 50
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:header-rows: 1
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* - Backend
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- Description
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* - ``torch.compile(m, backend="inductor")``
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- Uses the TorchInductor backend. `Read more <https://dev-discuss.pytorch.org/t/torchinductor-a-pytorch-native-compiler-with-define-by-run-ir-and-symbolic-shapes/747>`__
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* - ``torch.compile(m, backend="cudagraphs")``
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- CUDA graphs with AOT Autograd. `Read more <https://github.com/pytorch/torchdynamo/pull/757>`__
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* - ``torch.compile(m, backend="ipex")``
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- Uses IPEX on CPU. `Read more <https://github.com/intel/intel-extension-for-pytorch>`__
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* - ``torch.compile(m, backend="onnxrt")``
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- Uses ONNX Runtime for training on CPU/GPU. :doc:`Read more <onnx_dynamo_onnxruntime_backend>`
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**Inference-only backends**
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.. list-table::
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:widths: 50 50
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:header-rows: 1
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* - Backend
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- Description
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* - ``torch.compile(m, backend="tensorrt")``
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- Uses Torch-TensorRT for inference optimizations. Requires ``import torch_tensorrt`` in the calling script to register backend. `Read more <https://github.com/pytorch/TensorRT>`__
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* - ``torch.compile(m, backend="ipex")``
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- Uses IPEX for inference on CPU. `Read more <https://github.com/intel/intel-extension-for-pytorch>`__
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* - ``torch.compile(m, backend="tvm")``
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- Uses Apache TVM for inference optimizations. `Read more <https://tvm.apache.org/>`__
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* - ``torch.compile(m, backend="openvino")``
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- Uses OpenVINO for inference optimizations. `Read more <https://docs.openvino.ai/torchcompile>`__
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Read More
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~~~~~~~~~
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.. toctree::
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:caption: Getting Started for PyTorch Users
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:maxdepth: 1
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torch.compiler_get_started
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torch.compiler_api
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torch.compiler.config
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torch.compiler_fine_grain_apis
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torch.compiler_aot_inductor
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torch.compiler_inductor_profiling
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torch.compiler_profiling_torch_compile
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torch.compiler_faq
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torch.compiler_troubleshooting
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torch.compiler_performance_dashboard
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..
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_If you want to contribute a developer-level topic
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that provides in-depth overview of a torch._dynamo feature,
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add in the below toc.
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.. toctree::
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:caption: Deep Dive for PyTorch Developers
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:maxdepth: 1
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torch.compiler_dynamo_overview
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torch.compiler_dynamo_deepdive
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torch.compiler_dynamic_shapes
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torch.compiler_nn_module
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torch.compiler_best_practices_for_backends
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torch.compiler_cudagraph_trees
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torch.compiler_fake_tensor
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.. toctree::
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:caption: HowTo for PyTorch Backend Vendors
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:maxdepth: 1
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torch.compiler_custom_backends
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torch.compiler_transformations
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torch.compiler_ir
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