Noted. Thanks all for the tips ! On 16-Dec-2013 2:36 pm, "Jeff Squyres (jsquyres)" <jsquy...@cisco.com> wrote:
> Everything that Brian said, plus: note that the MCA param that Christoph > mentioned is specifically for the "sm" (shared memory) transport. Each > transport has their own set of MCA params (e.g., mca_btl_tcp_eager_limit, > and friends). > > > On Dec 16, 2013, at 3:19 PM, "Barrett, Brian W" <bwba...@sandia.gov> > wrote: > > > Siddhartha - > > > > Christoph mentioned how to change the cross-over for shared memory, but > it's really per-transport (so you'd have to change it for your off-node > transport as well). That's all in the FAQ you mentioned, so hopefully you > can take it from there. Note that, in general, moving the eager limits has > some unintended side effects. For example, it can cause more / less > copies. It can also greatly increase memory usage. > > > > Good luck, > > > > Brian > > > > On 12/16/13 1:49 AM, "Siddhartha Jana" <siddharthajan...@gmail.com> > wrote: > > > >> Thanks Christoph. > >> I should have looked into the FAQ section on MCA params setting @ : > >> http://www.open-mpi.org/faq/?category=tuning#available-mca-params > >> > >> Thanks again, > >> -- Siddhartha > >> > >> > >> On 16 December 2013 02:41, Christoph Niethammer <nietham...@hlrs.de> > wrote: > >>> Hi Siddhartha, > >>> > >>> MPI_Send/Recv in Open MPI implements both protocols and chooses based > on the message size which one to use. > >>> You can use the mca parameter "btl_sm_eager_limit" to modify the > behaviour. > >>> > >>> Here the corresponding info obtained from the ompi_info tool: > >>> > >>> "btl_sm_eager_limit" (current value: <4096>, data source: default > value) > >>> Maximum size (in bytes) of "short" messages (must be >= 1) > >>> > >>> Regards > >>> Christoph Niethammer > >>> > >>> -- > >>> > >>> Christoph Niethammer > >>> High Performance Computing Center Stuttgart (HLRS) > >>> Nobelstrasse 19 > >>> 70569 Stuttgart > >>> > >>> Tel: ++49(0)711-685-87203 > >>> email: nietham...@hlrs.de > >>> http://www.hlrs.de/people/niethammer > >>> > >>> > >>> > >>> ----- Ursprüngliche Mail ----- > >>> Von: "Siddhartha Jana" <siddharthajan...@gmail.com> > >>> An: "OpenMPI users mailing list" <us...@open-mpi.org> > >>> Gesendet: Samstag, 14. Dezember 2013 13:44:12 > >>> Betreff: [OMPI users] Configuration for rendezvous and eager > protocols: two-sided comm > >>> > >>> > >>> > >>> Hi > >>> > >>> > >>> In OpenMPI, are MPI_Send, MPI_Recv (and friends) implemented using > rendezvous protocol or eager protocol? > >>> > >>> > >>> If both, is there a way to choose one or the other during runtime or > while building the library? > >>> > >>> > >>> If there is a threshold of the message size that dictates the protocol > to be used, is there a way I can alter that threshold value? > >>> > >>> > >>> If different protocols were used for different versions of the library > in the past, could someone please direct me to the exact version numbers of > the implementations that used one or the other protocol? > >>> > >>> > >>> Thanks a lot, > >>> Siddhartha > >>> _______________________________________________ > >>> users mailing list > >>> 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 > >> > > > > > > -- > > Brian W. Barrett > > Scalable System Software Group > > Sandia National Laboratories > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > -- > Jeff Squyres > jsquy...@cisco.com > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
