Yes this is why we've suggested it for folks to use as the default, for the
sstat feature! ( And to make it simple for everyone.
—
Christopher Coffey
High-Performance Computing
Northern Arizona University
928-523-1167
On 2/22/18, 3:00 PM, "slurm-users on behalf of Chris Samuel"
wrote:
O
On 23/02/18 21:50, Loris Bennett wrote:
OK, I'm confused now. Our main culprit for producing processes with
incorrect affinity is ORCA [1]. It uses OpenMPI but also likes to
start processes asynchronously via SSH within the node set.
In that case (and for the general case where there are wr
Hi Chris,
Christopher Benjamin Coffey writes:
> Hi Loris,
>
>> But that's only the case if the program is started with srun or some
>> form of mpirun. Otherwise the program just gets started once on one
>> core and the other cores just idle.
>
> Yes, maybe that’s true about what you say when no
On Friday, 23 February 2018 7:57:54 AM AEDT Christopher Benjamin Coffey wrote:
> Yes, maybe that’s true about what you say when not using srun. I'm not sure,
> as we tell everyone to use srun to launch every type of task.
I've not done that out of habit with users, but it has one really useful si
On 02/22/2018 07:50 AM, Christopher Benjamin Coffey wrote:
It’s a big deal if folks use -n when it’s not an mpi program. This is because
the non mpi program is launched n times (instead of once with internal threads)
and will stomp over logs and output files (uncoordinated) leading to poor
per
Hi Loris,
"But that's only the case if the program is started with srun or some form
of mpirun. Otherwise the program just gets started once on one core and
the other cores just idle."
Yes, maybe that’s true about what you say when not using srun. I'm not sure, as
we tell everyone to
...@lists.schedmd.com] On Behalf Of
Miguel Gutiérrez Páez
Sent: Thursday, February 22, 2018 3:07 AM
To: Slurm User Community List
Subject: Re: [slurm-users] ntasks and cpus-per-task
Hi,
That was just I thought, ntasks for mpi and cpus-per-task for multithreading.
So, for example, if every node has 24
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 writes:
At least from
Hi Paul,
Paul Edmon 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 para
Hi, Other Chris,
Christopher Benjamin Coffey writes:
> Loris,
>
> It’s simple, tell folks only to use -n for mpi jobs, and -c otherwise
> (default).
>
> It’s a big deal if folks use -n when it’s not an mpi program. This is
> because the non mpi program is launched n times (instead of once with
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 affin
Loris,
It’s simple, tell folks only to use -n for mpi jobs, and -c otherwise
(default).
It’s a big deal if folks use -n when it’s not an mpi program. This is because
the non mpi program is launched n times (instead of once with internal threads)
and will stomp over logs and output files (unco
Hi,
That was just I thought, ntasks for mpi and cpus-per-task for
multithreading.
So, for example, if every node has 24 cores, is there any difference
between these commands?
sbatch --ntasks 24 [...]
sbatch --ntasks 1 --cpus-per-task 24 [...]
regards.
El jue., 22 feb. 2018 a las 9:52, Loris Ben
Hi Chris,
Christopher Samuel writes:
> On 22/02/18 18:49, Miguel Gutiérrez Páez wrote:
>
>> What's the real meaning of ntasks? Has cpus-per-task and ntasks the
>> same meaning in sbatch and srun?
>
> --ntasks is for parallel distributed jobs, where you can run lots of
> independent processes tha
On 22/02/18 18:49, Miguel Gutiérrez Páez wrote:
What's the real meaning of ntasks? Has cpus-per-task and ntasks the
same meaning in sbatch and srun?
--ntasks is for parallel distributed jobs, where you can run lots of
independent processes that collaborate using some form of communication
betw
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