fixed masked flash attention #2589
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I think it would be great to explain in this PR when and how the key_pad_mask needs to be used, and being clear in the different scenarii (standard, flash, sdpa mechanisms) |
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This PR proposes a fix for the flash attention path in the multi-head attention module.
The flash attention block doesn't support the left padding mask, so we apply it upstream.
Dao-AILab/flash-attention#649
We apply the
key_pad_maskto the values contained in the KV-cache at the first step only, for all scenari (standard, flash, sdpa mechanisms).