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!
