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A high-throughput and memory-efficient inference and serving engine for LLMs

Mirrored from https://github.com/tduncan-lum/Nvidia-Optimization-Stack---VLLM.git

Synced Nov 7, 14:00 UTC

[EPLB] Enforce sync eplb for NCCL-based all2all backend (#35212)

Signed-off-by: ilmarkov <markovilya197@gmail.com>

Ilya Markov committed Feb 28, 2026 at 06:47 UTC b2d8b422b2014b23c44fea703c70331eef35e7a1
1 file changed +11
vllm/config/parallel.py
+11
@@ -774,6 +774,17 @@ class ParallelConfig:
774 "backend is mp, uni or external_launcher."
775 )
776
777 + if (
778 + self.all2all_backend in ("allgather_reducescatter", "naive")
779 + and self.eplb_config.use_async
780 + ):
781 + logger.warning(
782 + "Async EPLB causes hangs with the '%s' all2all backend. "
783 + "Forcing synchronous EPLB.",
784 + self.all2all_backend,
785 + )
786 + self.eplb_config.use_async = False
787 +
788 @property
789 def use_ray(self) -> bool:
790 return self.distributed_executor_backend == "ray" or (