[perf] Use CPU tensor to reduce GPU->CPU sync #25884
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Signed-off-by: Lehua Ding <lehuading@tencent.com>
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Code Review
This pull request introduces a performance optimization to reduce GPU-to-CPU synchronization during speculative decoding. The change replaces a call to .max() on a GPU tensor (seq_lens) with its CPU counterpart (seq_lens_cpu) within a conditional check. This avoids a blocking operation, which is particularly beneficial for asynchronous scheduling. The change is correct and aligns with the stated goal of improving performance. I have no further comments.
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Which introduce by this pr(#24662), @AlonKejzman can you help review this too? thanks. |
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Sep 29, 2025
Signed-off-by: Lehua Ding <lehuading@tencent.com>
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Use
seq_lens_cpuinstead ofseq_lensto reduce GPU->CPU sync.Purpose
Reduce unnecessary GPU->CPU sync, since it will affect the perf of Async Scheduling+MTP.
Test Plan
Test Result
Essential Elements of an Effective PR Description Checklist
supported_models.mdandexamplesfor a new model.