On Fri, Dec 01, 2006 at 04:14:31PM +0200, Gleb Natapov wrote: > On Fri, Dec 01, 2006 at 11:51:24AM +0100, Peter Kjellstrom wrote: > > On Saturday 25 November 2006 15:31, shap...@isp.nsc.ru wrote: > > > Hello, > > > i cant figure out, is there a way with open-mpi to bind all > > > threads on a given node to a specified subset of CPUs. > > > For example, on a multi-socket multi-core machine, i want to use > > > only a single core on each CPU. > > > Thank You. > > > > This might be a bit naive but, if you spawn two procs on a dual core dual > > socket system then the linux kernel should automagically schedule them this > > way. > > > > I actually think this applies to most of the situations discussed in this > > thread. Explicitly assigning processes to cores may actually get it wrong > > more often than the normal linux scheduler. > > > If you run two single threaded ranks on the dual core dual socket node > you better be placing them on the same core. Shared memory communication I mean "same socket" here and not "same core" of cause.
> will be much faster (especially if two cores shares cache). > > > /Peter (who may be putting a bit too much faith in the linux scheduler...) > Linux scheduler does its best assuming the processes are unrelated. This is > not the case with MPI ranks. > > -- > Gleb. > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users -- Gleb.
