We should fix the RMA chapter with an erratum. I care less about NBC but share your ignorance of why it was done that way.
Sent from my iPhone > On Aug 8, 2020, at 6:51 AM, Balaji, Pavan via mpi-forum > <mpi-forum@lists.mpi-forum.org> wrote: > > Folks, > > Does someone remember why we disallowed users from calling MPI_Request_free > on nonblocking collective requests? I remember the reasoning for not > allowing cancel (i.e., the operation might have completed on some processes, > but not all), but not for Request_free. AFAICT, allowing the users to free > the request doesn’t make any difference to the MPI library. The MPI library > would simply maintain its own refcount to the request and continue forward > till the operation completes. One of our users would like to free NBC > requests so they don’t have to wait for the operation to complete in some > situations. > > Unfortunately, when I added the Rput/Rget operations in the RMA chapter, I > copy-pasted that text into RMA as well without thinking too hard about it. > My bad! Either the RMA committee missed it too, or they thought of a reason > that I can’t think of now. > > Can someone clarify or remind me what the reason was? > > Regards, > > — Pavan > > MPI-3.1 standard, page 197, lines 26-27: > > “It is erroneous to call MPI_REQUEST_FREE or MPI_CANCEL for a request > associated with a nonblocking collective operation.” > > _______________________________________________ > mpi-forum mailing list > mpi-forum@lists.mpi-forum.org > https://lists.mpi-forum.org/mailman/listinfo/mpi-forum
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