480 lines
21 KiB
Python
480 lines
21 KiB
Python
import gc
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from typing import Optional
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import torch
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from torch.utils import _pytree
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from .._utils import _dummy_type
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if not hasattr(torch._C, "_CudaStreamBase"):
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# Define dummy base classes
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torch._C.__dict__["_CUDAGraph"] = _dummy_type("_CUDAGraph")
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torch._C.__dict__["_graph_pool_handle"] = _dummy_type("_graph_pool_handle")
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torch._C.__dict__["_cuda_isCurrentStreamCapturing"] = _dummy_type(
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"_cuda_isCurrentStreamCapturing"
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)
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from torch._C import ( # noqa: F401
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_cuda_isCurrentStreamCapturing,
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_CUDAGraph,
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_graph_pool_handle,
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)
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def is_current_stream_capturing():
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r"""Return True if CUDA graph capture is underway on the current CUDA stream, False otherwise.
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If a CUDA context does not exist on the current device, returns False without initializing the context.
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"""
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return _cuda_isCurrentStreamCapturing()
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# Python shim helps Sphinx process docstrings more reliably.
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def graph_pool_handle():
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r"""Return an opaque token representing the id of a graph memory pool.
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See :ref:`Graph memory management<graph-memory-management>`.
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.. warning::
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This API is in beta and may change in future releases.
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"""
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return _graph_pool_handle()
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# Python shim helps Sphinx process docstrings more reliably.
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class CUDAGraph(torch._C._CUDAGraph):
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r"""Wrapper around a CUDA graph.
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.. warning::
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This API is in beta and may change in future releases.
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"""
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def __new__(cls):
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return super().__new__(cls)
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def capture_begin(self, pool=None, capture_error_mode="global"):
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r"""Begin capturing CUDA work on the current stream.
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Typically, you shouldn't call ``capture_begin`` yourself.
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Use :class:`~torch.cuda.graph` or :func:`~torch.cuda.make_graphed_callables`,
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which call ``capture_begin`` internally.
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Arguments:
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pool (optional): Token (returned by :func:`~torch.cuda.graph_pool_handle` or
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:meth:`other_Graph_instance.pool()<torch.cuda.CUDAGraph.pool>`) that hints this graph may share memory
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with the indicated pool. See :ref:`Graph memory management<graph-memory-management>`.
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capture_error_mode (str, optional): specifies the cudaStreamCaptureMode for the graph capture stream.
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Can be "global", "thread_local" or "relaxed". During cuda graph capture, some actions, such as cudaMalloc,
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may be unsafe. "global" will error on actions in other threads, "thread_local" will only error for
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actions in the current thread, and "relaxed" will not error on these actions. Do NOT change this setting
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unless you're familiar with `cudaStreamCaptureMode <https://docs.nvidia.com/cuda/cuda-runtime-api/group__CUDART__STREAM.html#group__CUDART__STREAM_1g9d0535d93a214cbf126835257b16ba85>`_
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""" # noqa: B950
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super().capture_begin(pool=pool, capture_error_mode=capture_error_mode)
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def capture_end(self):
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r"""End CUDA graph capture on the current stream.
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After ``capture_end``, ``replay`` may be called on this instance.
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Typically, you shouldn't call ``capture_end`` yourself.
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Use :class:`~torch.cuda.graph` or :func:`~torch.cuda.make_graphed_callables`,
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which call ``capture_end`` internally.
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"""
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super().capture_end()
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def replay(self):
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r"""Replay the CUDA work captured by this graph."""
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super().replay()
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def reset(self):
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r"""Delete the graph currently held by this instance."""
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super().reset()
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def pool(self):
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r"""Return an opaque token representing the id of this graph's memory pool.
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This id can optionally be passed to another graph's ``capture_begin``,
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which hints the other graph may share the same memory pool.
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"""
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return super().pool()
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def enable_debug_mode(self):
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r"""Enable debugging mode for CUDAGraph.debug_dump."""
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return super().enable_debug_mode()
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def debug_dump(self, debug_path):
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r"""
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Arguments:
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debug_path (required): Path to dump the graph to.
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Calls a debugging function to dump the graph if the debugging is
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enabled via CUDAGraph.enable_debug_mode()
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"""
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return super().debug_dump(debug_path)
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class graph:
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r"""Context-manager that captures CUDA work into a :class:`torch.cuda.CUDAGraph` object for later replay.
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See :ref:`CUDA Graphs <cuda-graph-semantics>` for a general introduction,
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detailed use, and constraints.
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Arguments:
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cuda_graph (torch.cuda.CUDAGraph): Graph object used for capture.
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pool (optional): Opaque token (returned by a call to :func:`~torch.cuda.graph_pool_handle()` or
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:meth:`other_Graph_instance.pool()<torch.cuda.CUDAGraph.pool>`) hinting this graph's capture
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may share memory from the specified pool. See :ref:`Graph memory management<graph-memory-management>`.
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stream (torch.cuda.Stream, optional): If supplied, will be set as the current stream in the context.
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If not supplied, ``graph`` sets its own internal side stream as the current stream in the context.
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capture_error_mode (str, optional): specifies the cudaStreamCaptureMode for the graph capture stream.
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Can be "global", "thread_local" or "relaxed". During cuda graph capture, some actions, such as cudaMalloc,
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may be unsafe. "global" will error on actions in other threads, "thread_local" will only error for
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actions in the current thread, and "relaxed" will not error on actions. Do NOT change this setting
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unless you're familiar with `cudaStreamCaptureMode <https://docs.nvidia.com/cuda/cuda-runtime-api/group__CUDART__STREAM.html#group__CUDART__STREAM_1g9d0535d93a214cbf126835257b16ba85>`_
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.. note::
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For effective memory sharing, if you pass a ``pool`` used by a previous capture and the previous capture
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used an explicit ``stream`` argument, you should pass the same ``stream`` argument to this capture.
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.. warning::
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This API is in beta and may change in future releases.
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.. _cudaStreamCaptureMode:
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https://docs.nvidia.com/cuda/cuda-runtime-api/group__CUDART__STREAM.html#group__CUDART__STREAM_1g9d0535d93a214cbf126835257b16ba85
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""" # noqa: B950
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default_capture_stream: Optional["torch.cuda.Stream"] = None
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def __init__(
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self,
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cuda_graph,
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pool=None,
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stream=None,
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capture_error_mode: str = "global",
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):
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# Lazy-init of default_capture_stream helps avoid circular-import errors.
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# Not thread safe, but graphs already have the general (explicitly documented)
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# restriction that only one capture may be underway at a time in the process.
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if self.__class__.default_capture_stream is None:
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self.__class__.default_capture_stream = torch.cuda.Stream()
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self.pool = () if pool is None else (pool,)
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self.capture_stream = (
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stream if stream is not None else self.__class__.default_capture_stream
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)
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assert self.capture_stream is not None
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self.stream_ctx = torch.cuda.stream(self.capture_stream)
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self.cuda_graph = cuda_graph
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self.capture_error_mode = capture_error_mode
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def __enter__(self):
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# Free as much memory as we can for the graph
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torch.cuda.synchronize()
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gc.collect()
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torch.cuda.empty_cache()
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# Stackoverflow seems comfortable with this pattern
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# https://stackoverflow.com/questions/26635684/calling-enter-and-exit-manually#39172487
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self.stream_ctx.__enter__()
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self.cuda_graph.capture_begin(
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*self.pool, capture_error_mode=self.capture_error_mode
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)
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def __exit__(self, exc_type, exc_value, traceback):
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self.cuda_graph.capture_end()
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self.stream_ctx.__exit__(exc_type, exc_value, traceback)
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# returning None should propagate exceptions from either capture_end or stream_ctx.__exit__()
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def make_graphed_callables(
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callables, sample_args, num_warmup_iters=3, allow_unused_input=False, pool=None
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):
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r"""Accept callables (functions or :class:`nn.Module<torch.nn.Module>`\ s) and returns graphed versions.
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Each graphed callable's forward pass runs its source callable's
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forward CUDA work as a CUDA graph inside a single autograd node.
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The graphed callable's forward pass also appends
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a backward node to the autograd graph. During backward, this node runs the
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callable's backward work as a CUDA graph.
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Therefore, each graphed callable should be a drop-in replacement for its source callable
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in an autograd-enabled training loop.
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See :ref:`Partial-network capture<partial-network-capture>` for detailed use and constraints.
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If you pass a tuple of several callables, their captures will use the same memory pool.
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See :ref:`Graph memory management<graph-memory-management>` for when this is appropriate.
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Arguments:
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callables (torch.nn.Module or Python function, or tuple of these): Callable or callables to graph.
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See :ref:`Graph memory management<graph-memory-management>` for when passing a tuple of callables
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is appropriate. If you pass a tuple of callables, their order in the tuple must be the same order
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they'll run in the live workload.
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sample_args (tuple of Tensors, or tuple of tuples of Tensors): Samples args for each callable.
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If a single callable was passed, ``sample_args`` must be a single tuple of argument Tensors.
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If a tuple of callables was passed, ``sample_args`` must be tuple of tuples of argument Tensors.
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num_warmup_iters (int): The number of warmup iterations. Currently, ``DataDistributedParallel`` needs
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11 iterations for warm up. Default: ``3``.
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allow_unused_input (bool): If False, specifying inputs that were not used when computing outputs
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(and therefore their grad is always zero) is an error. Defaults to False.
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pool (optional): Token (returned by :func:`~torch.cuda.graph_pool_handle` or
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:meth:`other_Graph_instance.pool()<torch.cuda.CUDAGraph.pool>`) that hints this graph may share memory
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with the indicated pool. See :ref:`Graph memory management<graph-memory-management>`.
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.. note::
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The ``requires_grad`` state of each Tensor in ``sample_args`` must match the state
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that's expected for the corresponding real input in the training loop.
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.. warning::
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This API is in beta and may change in future releases.
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.. warning::
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``sample_args`` for each callable must contain only Tensors. Other types are not allowed.
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.. warning::
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Returned callables do not support higher order differentiation (e.g., double backward).
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.. warning::
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In any :class:`~torch.nn.Module` passed to :func:`~make_graphed_callables`, only parameters
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may be trainable. Buffers must have ``requires_grad=False``.
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.. warning::
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After you pass a :class:`torch.nn.Module` through :func:`~make_graphed_callables`,
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you may not add or remove any of that Module's parameters or buffers.
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.. warning::
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:class:`torch.nn.Module`\s passed to :func:`~torch.cuda.make_graphed_callables` must not have module hooks
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registered on them at the time they are passed. However, registering hooks on modules *after* passing them
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through :func:`~torch.cuda.make_graphed_callables` is allowed.
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.. warning::
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When running a graphed callable, you must pass its arguments in the same order and format
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they appeared in that callable's ``sample_args``.
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.. warning::
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The automatic mixed precision is supported in :func:`~torch.cuda.make_graphed_callables` only with disabled
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caching. The context manager `torch.cuda.amp.autocast()` must have `cache_enabled=False`.
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"""
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if torch.is_autocast_enabled() and torch.is_autocast_cache_enabled():
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raise RuntimeError(
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"make_graphed_callables does not support the autocast caching. Please set `cache_enabled=False`."
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)
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just_one_callable = False
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if not isinstance(callables, tuple):
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just_one_callable = True
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callables = (callables,)
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sample_args = (sample_args,)
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flatten_sample_args = []
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for c, args in zip(callables, sample_args):
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if isinstance(c, torch.nn.Module):
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assert (
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len(c._backward_hooks) == 0
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and len(c._forward_hooks) == 0
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and len(c._forward_pre_hooks) == 0
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), (
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"Modules must not have hooks registered at the time they are passed. However, registering hooks "
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+ "on modules after passing them through make_graphed_callables is allowed."
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)
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assert all(b.requires_grad is False for b in c.buffers()), (
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"In any :class:`~torch.nn.Module` passed to "
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+ ":func:`~make_graphed_callables`, only parameters may be trainable. All buffers must have "
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+ "``requires_grad=False``."
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)
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flatten_arg = _pytree.arg_tree_leaves(*args)
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flatten_sample_args.append(tuple(flatten_arg))
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assert all(isinstance(arg, torch.Tensor) for arg in flatten_arg), (
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"In the beta API, sample_args "
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+ "for each callable must contain only Tensors. Other types are not allowed."
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)
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# If a callable is an nn.Module, its graph's full input surface is the args the user explicitly
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# passes to forward (ie, its sample_args) AND the module's parameter attributes.
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per_callable_len_user_args = [len(args) for args in flatten_sample_args]
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per_callable_module_params = [
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tuple(c.parameters()) if isinstance(c, torch.nn.Module) else ()
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for c in callables
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]
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per_callable_static_input_surfaces = [
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flatten_sample_args[i] + per_callable_module_params[i]
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for i in range(len(callables))
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]
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fwd_graphs = [torch.cuda.CUDAGraph() for _ in range(len(callables))]
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bwd_graphs = [torch.cuda.CUDAGraph() for _ in range(len(callables))]
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mempool = graph_pool_handle() if pool is None else pool
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# Warmup
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# Hopefully prevents cudnn benchmarking and other lazy-initialization cuda work
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# from ending up in any captures.
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torch.cuda.synchronize()
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with torch.cuda.stream(torch.cuda.Stream()):
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for func, args, static_input_surface in zip(
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callables, sample_args, per_callable_static_input_surfaces
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):
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for _ in range(num_warmup_iters):
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outputs = _pytree.tree_leaves(func(*args))
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grad_inputs = torch.autograd.grad(
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outputs=tuple(o for o in outputs if o.requires_grad),
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inputs=tuple(i for i in static_input_surface if i.requires_grad),
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grad_outputs=tuple(
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torch.empty_like(o) for o in outputs if o.requires_grad
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),
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only_inputs=True,
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allow_unused=allow_unused_input,
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)
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del outputs, grad_inputs # type: ignore[possibly-undefined]
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torch.cuda.synchronize()
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# All captures here share a mempool. To avoid replays corrupting each other's memory,
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# the safest approach is to capture all passes in the same order they'll run:
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# fwd 1, fwd 2, ... fwd N, then bwd N, bwd N-1, ... bwd 1.
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# Capture forward graphs
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per_callable_static_outputs = []
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per_callable_output_unflatten_spec = []
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for func, args, fwd_graph in zip(callables, sample_args, fwd_graphs):
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with torch.cuda.graph(fwd_graph, pool=mempool):
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outputs = func(*args)
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flatten_outputs, spec = _pytree.tree_flatten(outputs)
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per_callable_static_outputs.append(tuple(flatten_outputs))
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per_callable_output_unflatten_spec.append(spec)
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# Capture backward graphs in reverse order
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per_callable_static_grad_outputs = []
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per_callable_static_grad_inputs = []
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for static_input_surface, static_outputs, bwd_graph, module_params in zip(
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reversed(per_callable_static_input_surfaces),
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reversed(per_callable_static_outputs),
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reversed(bwd_graphs),
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reversed(per_callable_module_params),
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):
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# For now, assumes all static_outputs require grad
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# assert all(o.requires_grad for o in static_outputs), "Outputs of graphed callables must require grad."
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static_grad_outputs = tuple(
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torch.empty_like(o) if o.requires_grad else None for o in static_outputs
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)
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with torch.cuda.graph(bwd_graph, pool=mempool):
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grad_inputs = torch.autograd.grad(
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outputs=tuple(o for o in static_outputs if o.requires_grad),
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inputs=tuple(i for i in static_input_surface if i.requires_grad),
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grad_outputs=tuple(o for o in static_grad_outputs if o is not None),
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only_inputs=True,
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allow_unused=allow_unused_input,
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)
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# Constructs a tuple suitable for returning from Graphed.backward:
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# Pads out the actually-needed grads with Nones in gradient slots for inputs that don't require grad.
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# I couldn't think of a slick one-liner for this pattern.
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static_grad_inputs = []
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grad_idx = 0
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for arg in static_input_surface:
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if arg.requires_grad:
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static_grad_inputs.append(grad_inputs[grad_idx])
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grad_idx += 1
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else:
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static_grad_inputs.append(None) # type: ignore[arg-type]
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static_grad_inputs = tuple(static_grad_inputs) # type: ignore[assignment]
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per_callable_static_grad_outputs.append(static_grad_outputs)
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per_callable_static_grad_inputs.append(static_grad_inputs)
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# Reverses the most recent two lists
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per_callable_static_grad_outputs.reverse()
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per_callable_static_grad_inputs.reverse()
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# Now for every per_callable list, per_callable_*[i] holds the stuff for the ith callable.
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def make_graphed_autograd_function(
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fwd_graph,
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bwd_graph,
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module_params,
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len_user_args,
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output_unflatten_spec,
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static_input_surface,
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static_outputs,
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static_grad_outputs,
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static_grad_inputs,
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):
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class Graphed(torch.autograd.Function):
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@staticmethod
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def forward(ctx, *inputs):
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# At this stage, only the user args may (potentially) be new tensors.
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for i in range(len_user_args):
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if static_input_surface[i].data_ptr() != inputs[i].data_ptr():
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static_input_surface[i].copy_(inputs[i])
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fwd_graph.replay()
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assert isinstance(static_outputs, tuple)
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return tuple(o.detach() for o in static_outputs)
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@staticmethod
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@torch.autograd.function.once_differentiable
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def backward(ctx, *grads):
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assert len(grads) == len(static_grad_outputs)
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for g, grad in zip(static_grad_outputs, grads):
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if g is not None:
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# don't copy if autograd gods have been kind and the
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# incoming grad is already in the right place
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if g.data_ptr() != grad.data_ptr():
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g.copy_(grad)
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bwd_graph.replay()
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# Input args that didn't require grad expect a None gradient.
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assert isinstance(static_grad_inputs, tuple)
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return tuple(
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b.detach() if b is not None else b for b in static_grad_inputs
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)
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def functionalized(*user_args):
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# Runs the autograd function with inputs == all inputs to the graph that might require grad
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# (explicit user args + module parameters)
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# Assumes module params didn't change since capture.
|
|
flatten_user_args = _pytree.arg_tree_leaves(*user_args)
|
|
out = Graphed.apply(*(tuple(flatten_user_args) + module_params))
|
|
return _pytree.tree_unflatten(out, output_unflatten_spec)
|
|
|
|
return functionalized
|
|
|
|
# Put together the final graphed callables
|
|
ret = []
|
|
for i, func in enumerate(callables):
|
|
graphed = make_graphed_autograd_function(
|
|
fwd_graphs[i],
|
|
bwd_graphs[i],
|
|
per_callable_module_params[i],
|
|
per_callable_len_user_args[i],
|
|
per_callable_output_unflatten_spec[i],
|
|
per_callable_static_input_surfaces[i],
|
|
per_callable_static_outputs[i],
|
|
per_callable_static_grad_outputs[i],
|
|
per_callable_static_grad_inputs[i],
|
|
)
|
|
|
|
if isinstance(func, torch.nn.Module):
|
|
|
|
def make_graphed_forward(func, graph_training_state, graphed, orig_fwd):
|
|
def new_fwd(*user_args):
|
|
# If the module's training-or-eval state matches what we graphed,
|
|
# run the graph, otherwise run the original forward method
|
|
if func.training == graph_training_state:
|
|
return graphed(*user_args)
|
|
else:
|
|
return orig_fwd(*user_args)
|
|
|
|
return new_fwd
|
|
|
|
func.forward = make_graphed_forward(func, func.training, graphed, func.forward) # type: ignore[assignment]
|
|
ret.append(func)
|
|
else:
|
|
ret.append(graphed)
|
|
|
|
if just_one_callable:
|
|
return ret[0]
|
|
|
|
return tuple(ret)
|