[causal attn mask] replaced for loop over tensor with pytorch tensor ops#208
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dabeschte wants to merge 2 commits intoTencent-Hunyuan:mainfrom
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[causal attn mask] replaced for loop over tensor with pytorch tensor ops#208dabeschte wants to merge 2 commits intoTencent-Hunyuan:mainfrom
dabeschte wants to merge 2 commits intoTencent-Hunyuan:mainfrom
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dabeschte
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The original causal attention mask generation is very slow, especially when the tensor is created on the GPU, because it needs to make 1000s of calls.
I tried to compile it...which works and makes it fast too, but compilation unfortunately also takes a long time when using a long sequence length.
This implementation is ~20-70x faster depending on the sequence lengths and since it is re-created for every SDPA, this accumulates to multiple seconds per step for larger videos