[PyTorch] Deprecate unused is_cg_capturable in parallel_cross_entropy - #41
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[PyTorch] Deprecate unused is_cg_capturable in parallel_cross_entropy#41pggPL wants to merge 3 commits into
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Since NVIDIA#3273 the cross entropy backward no longer contains a synchronization point, so the operation is always CUDA graph capturable and the flag has no effect. Keep accepting it on the public API for backward compatibility (with a FutureWarning), drop the dead internal plumbing. Signed-off-by: Pawel Gadzinski <pgadzinski@nvidia.com>
Signed-off-by: Pawel Gadzinski <pgadzinski@nvidia.com>
Signed-off-by: Pawel Gadzinski <pgadzinski@nvidia.com>
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Superseded by NVIDIA#3455 |
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Description
Since NVIDIA#3273 the fused cross entropy backward reconstructs the derivative from saved statistics and no longer contains the
torch.equal-based synchronization point. Theis_cg_capturableflag therefore has no effect — the operation is always CUDA graph capturable.This PR marks the flag as deprecated on the public
parallel_cross_entropyAPI (docstring note +FutureWarningwhen set) and removes the dead internal plumbing. The parameter is kept in the signature for backward compatibility, since Megatron-LM passes it explicitly.Should also be mentioned as deprecated in the v2.19 release notes.
Type of change
Changes
Please list the changes introduced in this PR:
is_cg_capturableinparallel_cross_entropy: docstring now states it is unused, and passingTrueemits aFutureWarning.CrossEntropyFunction,_parallel_cross_entropy_overwrite_inputand the Tritoncross_entropy_backwardwrapper, where it was already a no-op.Checklist: