This limit is controlled by several MCA variables. Contiguous segments larger than the btl_openib_eager_limit will use the RDMA protocol (Get) if mpi_leave_pinned is set and the RDMA RNDV (Put) protocol otherwise. Both of these protocol pin the user buffer on both sides.
-Nathan On Fri, May 23, 2014 at 04:39:36PM -0500, Siddhartha Jana wrote: > Hi, > Is my understanding correct? > While servicing MPI_Send using eager protocol over openib, there is a > data-size threshold below which it is preferred to copy the contents of > the user-buffer to a pre-pinned buffer instead of directly pinning down > the user-buffer. If this is correct, how does one determine this > threshold? > As always, thanks for the help > Sid > _______________________________________________ > devel mailing list > de...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > Link to this post: > http://www.open-mpi.org/community/lists/devel/2014/05/14837.php
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