Hi,
@Gilles Awesome. --bind-to hwthread does the trick. I thought binding
and mapping would not be read if using --rankfile.
@Jeff I am running on a shared cluster. Some apps do use HT for
achieving better performance. Nothing we could do with BIOS settings.
Regards
On 08/09/2023 17:53, Jeff Squyres (jsquyres) wrote:
In addition to what Gilles mentioned, I'm curious: is there a reason
you have hardware threads enabled? You could disable them in the
BIOS, and then each of your MPI processes can use the full core, not
just a single hardware thread.
------------------------------------------------------------------------
*From:* users <users-boun...@lists.open-mpi.org> on behalf of Luis
Cebamanos via users <users@lists.open-mpi.org>
*Sent:* Friday, September 8, 2023 7:10 AM
*To:* Ralph Castain via users <users@lists.open-mpi.org>
*Cc:* Luis Cebamanos <luic...@gmail.com>
*Subject:* [OMPI users] Binding to thread 0
Hello,
Up to now, I have been using numerous ways of binding with wrappers
(numactl, taskset) whenever I wanted to play with core placing.
Another way I have been using is via -rankfile, however I notice that
some ranks jump from thread 0 to thread 1 on SMT chips. I can control
this with numactl for instance, but it would be great to see similar
behaviour when using -rankfile. Is there a way to pack all ranks to
one of the threads of each core (preferibly to thread 0) so I can
nicely see all ranks with htop on either left or right of the screen?
The command I am using is pretty simple:
mpirun -np $MPIRANKS --rankfile ./myrankfile
and ./myrankfile looks like
rank 33=argon slot=33
rank 34=argon slot=34
rank 35=argon slot=35
rank 36=argon slot=36
Thanks!
