coll/acoll: Bcast/Barrier enhancements and bug fixes. #13222
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Shared memory based implementations for bcast and barrier are enabled for within a node communication. Signed-off-by: Nithya V S <[email protected]>
Code changes to remove a few coverity scan warnings, fallbacks to base algorithms for custom datatypes. Signed-off-by: Nithya V S <[email protected]>
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May 9, 2025
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This PR introduces enhancements to Bcast and Barrier algorithms in acoll. Additionally, some bugs are fixed and code robustness is improved.
Enhancements:
-Shared memory-based implementations of MPI_Bcast and MPI_Barrier for intra-node communication are added. Performance improvements are observed till 8KB when using acoll bcast based on shared memory.
The following performance trends were observed when benchmarked on AMD EPYC 9755 128-Core Processor with 128 ranks:
-Two new mca parameters are introduced:
1. mca_coll_acoll_disable_shmbcast to enable/disable shared memory algorithm in bcast.
2. mca_coll_acoll_barrier_algo to select between hierarchical and flat shared memory barrier algorithm.
Others:
-A few coverity scan warnings in acoll are fixed.
-Added checks to ensure xpmem-based and shared memory-bsaed optimizations are disabled for non predefined data types or accelerator buffers.
-Improved error handling in various collectives in acoll.
-Simplified logic in coll_acoll_alltoall.c for selecting communication groups.