Fix unsafe collective reorder past wait #157489
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Covers the case where the output of one collective feeds the input of another collective. e.g. TP + FSDP - all_gather(tp+dp sharded param on TP dim) -> allgather dp_sharded buffer on DP dim Fixes a bug where the reordering pass specifically exempted wait nodes from dependencies. Note: this exemption was incorrect, so it should be removed. But it was also put there for a reason, to help move collectives past wait nodes that are not related to that collective. After this fix, reordering performance may be worse and we need to find a smarter way to decide if a particular wait node is a blocker for a given collective. [ghstack-poisoned]
🔗 Helpful Links🧪 See artifacts and rendered test results at hud.pytorch.org/pr/157489
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Merge startedYour change will be merged once all checks pass (ETA 0-4 Hours). Learn more about merging in the wiki. Questions? Feedback? Please reach out to the PyTorch DevX Team |
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Covers the case where the output of one collective feeds the input of another collective. e.g. TP + FSDP - all_gather(tp+dp sharded param on TP dim) -> allgather dp_sharded buffer on DP dim Fixes a bug where the reordering pass specifically exempted wait nodes from dependencies. Note: this exemption was incorrect, so it should be removed. But it was also put there for a reason, to help move collectives past wait nodes that are not related to that collective. After this fix, reordering performance may be worse and we need to find a smarter way to decide if a particular wait node is a blocker for a given collective. cc H-Huang awgu wanchaol fegin fduwjj wz337 d4l3k voznesenskym penguinwu EikanWang jgong5 Guobing-Chen XiaobingSuper zhuhaozhe blzheng wenzhe-nrv jiayisunx ipiszy chenyang78 kadeng muchulee8 amjames chauhang aakhundov [ghstack-poisoned]
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Covers the case where the output of one collective feeds the input of another collective. e.g. TP + FSDP - all_gather(tp+dp sharded param on TP dim) -> allgather dp_sharded buffer on DP dim Fixes a bug where the reordering pass specifically exempted wait nodes from dependencies. Note: this exemption was incorrect, so it should be removed. But it was also put there for a reason, to help move collectives past wait nodes that are not related to that collective. After this fix, reordering performance may be worse and we need to find a smarter way to decide if a particular wait node is a blocker for a given collective. ghstack-source-id: f946d9b Pull Request resolved: #157489
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Merge startedYour change will be merged while ignoring the following 1 checks: pull / cuda12.8-py3.10-gcc9-sm75 / test (pr_time_benchmarks, 1, 1, linux.g4dn.metal.nvidia.gpu, unstable) Learn more about merging in the wiki. Questions? Feedback? Please reach out to the PyTorch DevX Team |
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Stack from ghstack (oldest at bottom):
Covers the case where the output of one collective feeds the input of another collective.
e.g. TP + FSDP - all_gather(tp+dp sharded param on TP dim) -> allgather dp_sharded buffer on DP dim
Fixes a bug where the reordering pass specifically exempted wait nodes from dependencies.
Note: this exemption was incorrect, so it should be removed. But it was also put there for a reason, to help move collectives past wait nodes that are not related to that collective. After this fix, reordering performance may be worse and we need to find a smarter way to decide if a particular wait node is a blocker for a given collective.
cc @H-Huang @awgu @wanchaol @fegin @fduwjj @wz337 @d4l3k @voznesenskym @penguinwu @EikanWang @jgong5 @Guobing-Chen @XiaobingSuper @zhuhaozhe @blzheng @wenzhe-nrv @jiayisunx @ipiszy @chenyang78 @kadeng @muchulee8 @amjames @chauhang @aakhundov