Multiple multicore executions overlap

[Nortamo]

Background information

Simultaneous executions requesting multiple cores overlap.
Wondering if this is expected or a bug.

• prrte version v2.0.2
• pmix version v4.1.2

Please describe the system on which you are running

• Operating system/version:
  RHEL 7.9
• Computer hardware:
• ( Bull Sequana XH2000)
  AMD EPYC 7402 (dual socket)
• Network type:
  InfiniBand HDR200

---

Details of the problem

When launching multiple executions using prun the CPU binds overlap.

shell$ prun -np 1 --map-by node:pe=4 ./a.out

Would be placed on cores [0-3].
If another process is launched with the same settings (while the first one is still running) it will be placed on cores [1-4]. Instead of some non-overlapping range. Otherwise the affinity mapping works perfectly.

Full:

prun -np 1 --map-by node:pe=4 --display map-devel ./a.out &
prun -np 1 --map-by node:pe=4 --display map-devel ./a.out &

->

process on node1 with cores Cpus_allowed_list: 0-3,128-131
process on node1 with cores Cpus_allowed_list: 1-4,129-132

Is this expected behavior or am I perhaps missing some option or configuration to make the placement non-overlapping ? Based on the --display map-devel output multiple cpus/proc does not seem to affect the number of slots used.

Same behavior is observed when running locally and using slurm (21.08) integration (prrte started within a job allocation and srun starts prte on each node).

[rhc54]

Hmmm...that is clearly a bug. Will investigate.

[rhc54]

Found the bug - still working on it.

[rhc54]

Sorry for the lengthy delay - retirement has its privileges :-)

This is fixed in #1383