[ROCm] support triton-based flash-attn in TE #177
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ipanfilo
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May 2, 2025
| else: | ||
| if _flash_attn_version_required <= _flash_attn_version <= _flash_attn_max_version: | ||
| from flash_attn_2_cuda import varlen_bwd as flash_attn_cuda_bwd | ||
| if IS_HIP_EXTENSION and (os.getenv("FLASH_ATTENTION_TRITON_AMD_ENABLE", "FALSE")=="TRUE"): |
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It looks like flash_attn_cuda_bwd is only used on NV platform and only when explicitly requested by user. So this changes is not needed.
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It's used in our version as well:
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It exists in our version but not used. All its usages are under use_FAv2_bwd condition
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the use_FAv2_bwd is a parameter in the forward function of class FusedAttnFunc_qkvpacked, FusedAttnFunc_kvpacked and FusedAttnFunc, which user could set to true I guess? See
as an example. Then this flash_attn_cuda_bwd could be used somewhere else by customers
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In normal code-path use_FAv2_bwd is got from NVTE_FUSED_ATTN_USE_FAv2_BWD at
and it is always set to False for AMD devices there and later at
Indeed, users may call FusedAttnFunc* classes directly which will bypass a lot of other logic and checks so I wouldn't worry about this parameter specifically. For sanity, this feature may be explicitly disabled for ROCm but anyway keeping things as-is seems less evil than rely on independent project env variables.
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@wangye805 Could you rebase? |
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Description
Enable triton-based flash-attn in TE
Fixes # (issue)
Type of change
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