Enable shared-memory bypass comms for co-locales on InfiniBand #24944
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…use of co-locales This is necessary to ensure asynchronous progress of AMs arriving via the PSHM channel on ibv-conduit. Signed-off-by: bonachea <dobonachea@lbl.gov>
PSHM is the GASNet term for shared-memory bypass communication, which
routinely improves latency and overhead by 2-3 orders of magnitude
relative to communication using a loopback network channel.
PSHM is now only disabled for CHPL_MAKE_COMM_SEGMENT=everything,
where it is currently unavailable in GASNet.
This should result in greatly accelerated performance for co-locale
communication when using CHPL_COMM_SUBSTRATE={ibv,aries,mpi}, where PSHM
was previously disabled.
Signed-off-by: bonachea <dobonachea@lbl.gov>
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This PR is superseded by #25140 where @jhh67 is currently preparing to instead use GASNet's new |
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Overview
This PR enables GASNet-level shared-memory bypass communication for all GASNet conduits (in fast/large segment modes), which should notably greatly accelerate co-locale communication for
CHPL_COMM=gasnet CHPL_COMM_SUBSTRATE=ibv.This fixes the defect acknowledged in the original PR #13473 regarding use of PSHM with
CHPL_COMM_SUBSTRATE=ibv.TODO:
CHPL_GASNET_VERSION=ex). Assuming it proves valuable there, then an analogous change probably must be back-ported to the legacy GASNet-1 backend, to avoid breaking it in the presence of co-locales.CC: @PHHargrove , @ronawho , @jhh67