Thanks Guilles for the quick reply. I think I am confused about what the openib BTL specifies. What am I doing when I run with the openib BTL but specify my eth interface (...and deactivate my IB interfaces)? Is not openib only for IB interfaces? Am I using RDMA here?
These two commands give the same performance: mpirun --mca btl openib,self,sm -hostfile hosts_eth ... (With IB interfaces down) mpirun --mca btl openib,self,sm -hostfile hosts_ib0 ... Regards, Rodrigo On Mon, Mar 20, 2017 at 8:29 AM, Gilles Gouaillardet < gilles.gouaillar...@gmail.com> wrote: > You will get similar results with hosts_ib and hosts_eth > > If you want to use tcp over ethernet, you have to > mpirun --mca btl tcp,self,sm --mca btl_tcp_if_include eth0 ... > If you want to use tcp over ib, then > mpirun --mca btl tcp,self,sm --mca btl_tcp_if_include ib0 ... > > Keep in mind that IMB calls MPI_Init_thread(MPI_THREAD_MULTIPLE) > this is not only unnecessary here, but it also has an impact on > performances (with older versions, Open MPI felt back on IPoIB, > with v2.1rc the impact should be minimal) > > If you simply > mpirun --mca btl tcp,self,sm ... > then Open MPI will multiplex messages on both ethernet and IPoIB > > Cheers, > > Gilles > > > Rodrigo Escobar <rodave...@gmail.com> wrote: > Hi, > I have trying to run the Intel IMB benchmarks to compare the performance > of Infiniband (IB) vs Ethernet. However, I am not seeing any difference in > performance even for communication intensive benchmarks, such as alltoallv. > > Each one of my machines has one ethernet interface and an infiniband > interface. I use the following command to run the alltoallv benchmark: > mpirun --mca btl self,openib,sm -hostfile hosts_ib IMB-MPI1 alltoallv > > The hosts_ib file contains the IP addresses of the infiniband interfaces, > but the performance is the same when I deactivate the IB interfaces and use > my hosts_eth file which has the IP addresses of the ethernet interfaces. Am > I missing something? What is really happening when I specify the openib btl > if I am using the ethernet network? > > Thanks > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://rfd.newmexicoconsortium.org/mailman/listinfo/users >
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