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

[Paul Edmon]

Yeah, I've found that in those situations to have people wrap their 
threaded programs in srun inside of sbatch.  That way the scheduler 
knows which process specifically gets the threading.

-Paul Edmon-


On 02/22/2018 10:39 AM, Loris Bennett wrote:
> 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
>