I have a followup question on this. In our application we have parallel for loops similar to OMP parallel for. I noticed that in order to gain speedup with threads I've to set --bind-to none, otherwise multiple threads will bind to same core giving no increase in performance. For example, I get following (attached) performance for a simple 3point stencil computation run with T threads on 1 MPI process on 1 node (Tx1x1).
My understanding is even when there are multiple procs per node we should use --bind-to none in order to get performance with threads. Is this correct? Also, what's the disadvantage of not using --bind-to core? Thank you, Saliya On Wed, Feb 26, 2014 at 11:01 AM, Saliya Ekanayake <esal...@gmail.com>wrote: > Thank you Ralph, I'll check this. > > > On Wed, Feb 26, 2014 at 10:04 AM, Ralph Castain <r...@open-mpi.org> wrote: > >> It means that OMPI didn't get built against libnuma, and so we can't >> ensure that memory is being bound local to the proc binding. Check to see >> if numactl and numactl-devel are installed, or you can turn off the warning >> using "-mca hwloc_base_mem_bind_failure_action silent" >> >> >> On Feb 25, 2014, at 10:32 PM, Saliya Ekanayake <esal...@gmail.com> wrote: >> >> Hi, >> >> I tried to run an MPI Java program with --bind-to core. I receive the >> following warning and wonder how to fix this. >> >> >> WARNING: a request was made to bind a process. While the system >> supports binding the process itself, at least one node does NOT >> support binding memory to the process location. >> >> Node: 192.168.0.19 >> >> This is a warning only; your job will continue, though performance may >> be degraded. >> >> >> Thank you, >> Saliya >> >> -- >> Saliya Ekanayake esal...@gmail.com >> Cell 812-391-4914 Home 812-961-6383 >> http://saliya.org >> _______________________________________________ >> 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 >> > > > > -- > Saliya Ekanayake esal...@gmail.com > Cell 812-391-4914 Home 812-961-6383 > http://saliya.org > -- Saliya Ekanayake esal...@gmail.com Cell 812-391-4914 Home 812-961-6383 http://saliya.org
