(bench) add CCO api bench, similar to shmem#398
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jhchouuu
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Jun 16, 2026
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Motivation
Add a CCO p2p microbenchmark suite (put/get × bw/latency) mirroring benchmark/shmem/, covering both transports: LSA (intra-node P2P) and IGBDA (cross-node RDMA).
Technical Details
New benchmark/cco/ with 4 binaries; transport chosen via MORI_DISABLE_P2P. Issues found & fixed:
quietUntil (PSD) returned mid-transfer — unconditional break abandoned the CQ wait, inflating BW to multi-TB/s. Now breaks only on error.
LSA bw cache absorption — added per-iter __threadfence_system().
32-QP doorbell contention destabilized mid-size BW.
Build: BUILD_BENCHMARK now implies MPI; util.cpp builds as CXX.
Test Result
LSA/IGBDA saturate near NIC limit; GDA tests pas