[Mpi3-hybridpm] Shared memory segments proposal
dinan at mcs.anl.gov
Fri Nov 5 17:40:19 CDT 2010
I wanted to follow up on my questions during today's hybrid telecon.
Thanks, Ron, for taking the time to explain the shared memory segments
proposal and sorry if I took us off on a tangent. I just joined Argonne
in September so I wasn't able to arrange travel in time to join you all
I took a look at the slides and overall I think the shared memory
segments proposal is a good idea. It will provide a good alternative
for programmers who want to create node-level shared structures but want
to use processes instead of threads. I think that in order for this to
be more generally useful, we should consider adding something like
semaphores, mutexes, or some other data-driven (as opposed to send-recv
which will require an MPI rank) synchronization mechanism.
Another comment: Given that we are doing allocation collectively, could
we actually guarantee that the shared memory is mapped at the same base
pointer on every process? We do have MPI at our disposal so we could,
in principle, do some communication up front to coordinate a base
address that works for everyone before we map the shared segment.
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