[None][fix] gate NCCL window autotune pre-hook - #14566
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The allreduce autotuner can profile with dummy tensors. When the real input is not an NCCL symmetric window buffer, registering a dummy window input during autotune lets NCCL_SYMMETRIC look valid even though runtime later sees a regular tensor and pays the extra copy or falls back. Add an NCCL-window buffer detector and include the real input window state in the allreduce runner identity. Only install the autotune pre-hook that allocates a symmetric window input when the real allreduce input already uses the NCCL symmetric memory window. Signed-off-by: Jin Li <59594262+liji-nv@users.noreply.github.com>
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nv-lschneider
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Thanks for upgrading the logic for the auto-tuning.
I think we should strive to get more inputs to be window backed if possible, but this is the correct logic for all inputs we haven't upgraded yet.
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PR_Github #50339 [ run ] completed with state |
hyukn
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The allreduce autotuner can profile with dummy tensors. When the real input is not an NCCL symmetric window buffer, registering a dummy window input during autotune lets some fallback tactic get incorrect perf result.
Add an NCCL-window buffer detector and include the real input window state in the allreduce runner identity. Only install the autotune pre-hook that allocates a symmetric window input when the real allreduce input already uses the NCCL symmetric memory window.
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