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Support 2CTA for sliding window hdim 192#2347

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tridao merged 4 commits intoDao-AILab:mainfrom
Inodayy:enable-2cta-window-hdim192
Mar 19, 2026
Merged

Support 2CTA for sliding window hdim 192#2347
tridao merged 4 commits intoDao-AILab:mainfrom
Inodayy:enable-2cta-window-hdim192

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@Inodayy
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@Inodayy Inodayy commented Mar 13, 2026

Closes #2286

Keep 2CTA enabled for SM100 backward sliding window when head_dim = 192, which avoids the Must use 2CTA for hdim 192 assertion.

Validated on B300 with the given repro.

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tridao commented Mar 14, 2026

@tzadouri @jayhshah what was the concern w 2CTA and local? The tile scheduler is tricky?

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jayhshah commented Mar 16, 2026

@tzadouri @jayhshah what was the concern w 2CTA and local? The tile scheduler is tricky?

@tridao Sorry, there wasn't a good reason, I was thinking there might be issues with tile scheduling but that's not the case. It seems good to just disable the asserts and use the code as is for local.

In fact, we could also use 2CTA for hdim 128 local.

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tridao commented Mar 18, 2026

Can you enable the tests that will hit this code path?

@Inodayy Inodayy closed this Mar 18, 2026
@Inodayy Inodayy reopened this Mar 18, 2026
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tridao commented Mar 18, 2026

LGTM, we can merge when it's ready

@tridao tridao merged commit 07bd3af into Dao-AILab:main Mar 19, 2026
zhuochenKIDD pushed a commit to zhuochenKIDD/flash-attention that referenced this pull request Mar 25, 2026
* Support 2CTA for sliding window hdim 192

* Remove local 2CTA restriction in SM100 backward

* Enable SM100 backward local tests for hdim 192
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[Cute][B300] Please support 2CTA for sliding window with head dim 192

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