Interesting. I would like to understand more on how QP implementation in OpenMPI, for example, heuristics behind creating multiple QPs between two mpi processes.
Is there any whitepaper / reference / manual that I can refer to for that? Or can you point me to the source code region for this? Thanks, --Joba On Fri, Jun 7, 2013 at 8:09 AM, Shamis, Pavel <sham...@ornl.gov> wrote: > > Does that mean, if there is a AllGatherV and assuming that every process > belongs to default comm, there will n-1 Queue Pair between the collecting > process and other processes ? > n = total number of MPI processes. > > The answer depends on multiple parameters, like number of processes, > message size, etc. Some algorithms will require O(log(n)) connections other > O(n). > Also on OpenIB btl level per rank we create multiple QPs , not just one. > To make things even more complicated :-) there are multiple types of QPs, > like RC and XRC. > > -Pasha > > > > -- > Joba > > On Thu, Jun 6, 2013 at 3:37 PM, Shamis, Pavel <sham...@ornl.gov<mailto: > sham...@ornl.gov>> wrote: > Default implementation of collectives is based on PML (p2p layer) that is > implemented on top of BTL. > Consequently it laverages RDMA capabilities to some extend. > > Pavel (Pasha) Shamis > --- > Computer Science Research Group > Computer Science and Math Division > Oak Ridge National Laboratory > > > > > > > On Jun 6, 2013, at 1:59 PM, Jingcha Joba <pukkimon...@gmail.com<mailto: > pukkimon...@gmail.com><mailto:pukkimon...@gmail.com<mailto: > pukkimon...@gmail.com>>> wrote: > > Hi, > > I have a quick question. > > Is there an openib (in btl framework) equivalent in coll framework? > > I have an MPI application with gatherv and scatterv. I am wondering if I > can leverage RDMA capabilities of the underlying Infiniband fabric. > > > Thanks, > -- > Joba > > _______________________________________________ > users mailing list > us...@open-mpi.org<mailto:us...@open-mpi.org><mailto:us...@open-mpi.org > <mailto:us...@open-mpi.org>> > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > _______________________________________________ > users mailing list > us...@open-mpi.org<mailto:us...@open-mpi.org> > http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > users mailing list > us...@open-mpi.org<mailto:us...@open-mpi.org> > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
