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[CPU] Optimize FP8 QSDPA #3541

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[CPU] Optimize FP8 QSDPA #3541

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@Valentine233 Valentine233 commented Dec 25, 2025

Descriptions:

  • Fuse the transpose and packing for Key.
  • Use the fast exp implementation.
  • Tune the block size of flash attention.

Validation:

  • For model ViT on DMR, we see a kernel improvement of 50% and E2E speedup of 10%.
  • Accuracy is as good as before.

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pytorch-bot bot commented Dec 25, 2025 •
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🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/ao/3541

Note: Links to docs will display an error until the docs builds have been completed.

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@Valentine233 Valentine233 marked this pull request as draft December 25, 2025 05:47
@meta-cla meta-cla bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Dec 25, 2025
@Valentine233 Valentine233 added the topic: not user facing Use this tag if you don't want this PR to show up in release notes label Dec 25, 2025
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Valentine233 commented Dec 25, 2025

@mingfeima, please help review the PR.

@Valentine233 Valentine233 marked this pull request as ready for review December 25, 2025 08:43
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drisspg commented Dec 25, 2025

Cc @howardzhang-cv

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Valentine233 commented Jan 5, 2026

@drisspg @howardzhang-cv @jerryzh168 Please take a review on this PR, thanks!

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@jansel jansel Awaiting requested review from jansel

@jerryzh168 jerryzh168 Awaiting requested review from jerryzh168

@drisspg drisspg Awaiting requested review from drisspg

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@mingfeima mingfeima mingfeima approved these changes

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