Am 10.01.2018 um 16:55 schrieb Jeff Squyres (jsquyres): > See https://www.open-mpi.org/faq/?category=tuning#setting-mca-params for a > little more info on how to set MCA params.
Thanks! > In terms of physical vs. logical -- are you talking about hyperthreading? Yes. > If so, Open MPI uses the number of *cores* (by default), because that's what > "most" HPC users want (I put "most" in quotes because this can quickly turn > into a religious debate -- the "cores vs. hyperthreads" discussion has come > up on this list a few times over the years, and "most" HPC-related workloads > still tend to benefit from using a whole core vs. a hyperthread). Not wanting to open that debate again ;-). I was just surprised because most applications take the logical (hyperthreading) number of CPUs. Best, Florian > > Regardless, you can have Open MPI use hyperthreads by default (instead of > cores) with the mpirun option --use-hwthread-cpus. > > > >> On Jan 10, 2018, at 10:48 AM, r...@open-mpi.org wrote: >> >> Set the MCA param “rmaps_base_oversubscribe=1” in your default MCA param >> file, or in your environment >> >>> On Jan 10, 2018, at 4:42 AM, Florian Lindner <mailingli...@xgm.de> wrote: >>> >>> Hello, >>> >>> a recent openmpi update on my Arch machine seems to have enabled >>> --nooversubscribe, as described in the manpage. Since I >>> regularly test on my laptop with just 2 physical cores, I want to set >>> --oversubscribe by default. >>> >>> How can I do that? >>> >>> I am also a bit surprised, that openmpi takes the physical number of cores >>> into account, not the logical (which is 4 on >>> my machine). >>> >>> Thanks, >>> Florian >>> _______________________________________________ >>> users mailing list >>> users@lists.open-mpi.org >>> https://lists.open-mpi.org/mailman/listinfo/users >> >> _______________________________________________ >> users mailing list >> users@lists.open-mpi.org >> https://lists.open-mpi.org/mailman/listinfo/users > > _______________________________________________ users mailing list users@lists.open-mpi.org https://lists.open-mpi.org/mailman/listinfo/users
