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This was referenced Jan 5, 2026
BBuf
reviewed
Jan 7, 2026
| # solely on encoder_hidden_states (text), the (q_chunk * k) * v | ||
| # computation can be parallelized independently. Thus, there is | ||
| # no need to pass the config here. | ||
| parallel_config=(self._parallel_config if encoder_hidden_states is None else None), |
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Should this parallel_config be None?
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fixed #622
We need to disable the splitting of encoder_hidden_states because the image_encoder consistently generates 257 tokens for image_embed. This causes the shape of encoder_hidden_states—whose token count is always 769 (512 + 257) after concatenation—to be indivisible by the number of devices in the CP.
Since the key/value in cross-attention depends solely on encoder_hidden_states (text or img), the (q_chunk * k) * v computation can be parallelized independently. Thus, there is no need to pass the parallel_config for cross-attention. This change reduces redundant all-to-all communications—specifically (3+1)×2=8 for the two cross-attention operations (text and img)—thereby improving Wan’s performance under context parallelism.