Thank you Gilles, you're right, with --bind-to none we have ~ 15% of degradation rather than 50%.
It's much better now, but I think it should be (in theory) around 0%. The benchmark is MPI bound (the standard benchmark provided with SkaMPI), it tests these functions: MPI_Bcast, MPI_Barrier, MPI_Reduce, MPI_Allreduce, MPI_Alltoall, MPI_Gather, MPI_Scatter, MPI_Scan, MPI_Send/Recv Cheers, Federico __ Federico Reghenzani M.Eng. Student @ Politecnico di Milano Computer Science and Engineering 2016-01-25 12:17 GMT+01:00 Gilles Gouaillardet < gilles.gouaillar...@gmail.com>: > Federico, > > unless you already took care of that, I would guess all 16 orted > bound their children MPI tasks on socket 0 > > can you try > mpirun --bind-to none ... > > btw, is your benchmark application cpu bound ? memory bound ? MPI bound ? > > Cheers, > > Gilles > > > On Monday, January 25, 2016, Federico Reghenzani < > federico1.reghenz...@mail.polimi.it> wrote: > >> Hello, >> >> we have executed a benchmark (SkaMPI) on the same machine (32 core Intel >> Xeon 86_64) with these two configurations: >> - 1 orted with 16 processes with BTL forced to TCP (--mca btl self,tcp) >> - 16 orted with each 1 process (that uses TCP) >> >> We use a custom RAS to allow multiple orted on the same machine (I know >> that it seems non-sense to have multiple orteds on the same machine for the >> same application, but we are doing some experiments for migration). >> >> Initially we have expected approximately the same performance in both >> cases (we have 16 processes communicating via TCP in both cases), but we >> have a degradation of 50%, and we are sure that is not an overhead due to >> orteds initialization. >> >> Do you have any idea how can multiple orteds influence the processess >> performance? >> >> >> Cheers, >> Federico >> __ >> Federico Reghenzani >> M.Eng. Student @ Politecnico di Milano >> Computer Science and Engineering >> >> >> > _______________________________________________ > 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/2016/01/18499.php >
