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flash_attention: support also cross attention. #8427
flash_attention: support also cross attention. #8427
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In case that q and kv have different shapes (cross attention) flash attention with spmd fails since it does not support it.
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Rerun the tests when you can. @JackCaoG |
@JackCaoG when using XLA_DISABLE_FUNCTIONALIZATION=1, the flash attention backward tests are failing with error (unrelated to this PR specifically):
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hmm, not the first time I saw this issue, let me see if I can do anything before I return my laptop... |
I can repo the issue with
so this has nothing to do with segment ID. I check XLA it is from |
there is something more fundemenrtal, it seems like during the backward there is a graph break, I saw
before any mark_step, this is the cause of the crash above.. I tried to revert this pr but I still see the same graph break/ Need to first figure out where this is coming from. |
ok I found an even better repo, if I just mark_step in the fwd it will crash too
with functionizaiton
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Ok I narrowed it down to this line xla/torch_xla/experimental/custom_kernel.py Line 319 in 591c397
if I disable the functionizaiton and print |
ok I think the issue is in
the IR
next step is to look into where view logic kick in. @miladm I will let you find someone to follow up. |
@JackCaoG Hey! Can you merge this PR? is it fine? |
I am no longer with the team, you should check with @miladm |
In case that q and kv have different shapes (cross attention) flash attention with spmd fails since it does not support it.