[slurm-users] ntasks and cpus-per-task

[Loris Bennett]

Hi Paul,

Paul Edmon <pedmon at cfa.harvard.edu> writes:

> At least from my experience wonky things can happen with slurm
> (especially if you have thread affinity on) if you don't rightly
> divide between -n and -c.  In general I've been telling our users that
> -c is for threaded applications and -n is for rank based parallelism. 
> This way the thread affinity works out properly.

Actually we have do an issue with some applications not respecting the
CPU mask.  I always assumed it was something to do with the way the
multithreading was programmed in certain applications, but maybe we
should indeed be getting the users to use multiple CPUs with a single
task.

Thanks for the info.

Cheers,

Loris

-- 
Dr. Loris Bennett (Mr.)
ZEDAT, Freie Universität Berlin         Email loris.bennett at fu-berlin.de