The demo code affinity_test.c performs a dummy calculation
and prints out the affinity mask for each MPI process and OpenMP thread. Code can be compiled
with the included Makefile. Run the code with different OpenMP thread pinning settings
(OMP_PLACES, OMP_PROC_BIND) via the batch job system in Puhti and in Mahti. Try also cases where
you have less OpenMP threads than requested with --cpus-per-task.
You may try also printing the affinity mask with OpenMP environment variables (OMP_DISPLAY_AFFINITY)
In CSC's Slurm configuration it is quite difficult oversubscribe the cores, but if you manage to do so you should see significant increase in the time of the dummy calculation.