Optimize non fixed size segmented reduce for small segments using max_segment_size#7718
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srinivasyadav18 merged 18 commits intoNVIDIA:mainfrom Mar 10, 2026
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NaderAlAwar
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I think this PR is massively complicated by the fact that the segmented reduction dispatch was already refactored to the new tuning API, and the fixed size segmented dispatch was not. I strongly suggest to refactor the fixed size dispatch first (#7641) and then rebase this PR.
NaderAlAwar
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Nit: I believe int(...) is unnecessary here, since block_threads member of segmented_reduce_policy struct already is of type int.
uses cuda iterators in benchmark uses proper init for thrust vectors clean up docs in kernel disables sass check for c parallel segmented reduce test
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Performance Report:small, medium, large segments reduction code path using default max_segment_size 0NVIDIA RTX A6000 (SM 86)argmax T{ct}=F64 OffsetT=I32 - no regressions - mostly noisesum T{ct}=F64 OffsetT=I32 - no regressions - mostly noisesum T{ct}=I32 OffsetT=I32 - 3% regressions on small,medium segments which are already at < 5% SOLargmax T{ct}=I32 OffsetT=I32 - 3% regressions on small,medium segments which are already at < 5% SOL |
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I had a quick call with @srinivasyadav18 and here are some notes:
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miscco
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Implementation looks ok to me.
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🥳 CI Workflow Results🟩 Finished in 2h 18m: Pass: 100%/255 | Total: 8d 19h | Max: 2h 18m | Hits: 70%/157047See results here. |
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closes #6898
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