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Subject: Re: [OMPI users] Open MPI and SLURM_CPUS_PER_TASK
From: Ralph Castain (rhc_at_[hidden])
Date: 2011-11-30 16:30:25


Hi Igor

As I recall, this eventually traced back to a change in slurm at some point. I believe the latest interpretation is in line with your suggestion. I believe we didn't change it because nobody seemed to care very much, but I have no objection to including it in the next release.

Thanks
ralph

On Nov 28, 2011, at 3:50 AM, Igor Geier wrote:

> Dear all,
>
> there's been some discussions about this already, but the issue is still there (in 1.4.4). When running SLURM jobs with the --cpus-per-task parameter set (e.g. when running Open MPI-OpenMP jobs, so that --cpus-per-tasks corresponds to the number of OpenMP threads per rank), you get the
>
> "All nodes which are allocated for this job are already filled."
>
> error, if SLURM_CPUS_PER_TASK > SLURM_TASKS_PER_NODE. In ras_slurm_module.c, the number of slots is divided by the SLURM_CPUS_PER_TASK value (so that it becomes 0). The following patch seems to work for our cluster:
>
> --- a/orte/mca/ras/slurm/ras_slurm_module.c 2009-12-08 21:36:38.000000000 +0100
> +++ b/orte/mca/ras/slurm/ras_slurm_module.c 2011-11-25 12:28:55.000000000 +0100
> @@ -353,7 +353,8 @@
> node->state = ORTE_NODE_STATE_UP;
> node->slots_inuse = 0;
> node->slots_max = 0;
> - node->slots = slots[i] / cpus_per_task;
> + /* Don't divide by cpus_per_task */
> + node->slots = slots[i];
> opal_list_append(nodelist, &node->super);
> }
> free(slots);
>
> Are there situations where this might not work?
>
> Best regards
>
> Igor
>
> --
>
> Igor Geier
>
> --------------------------------------
> Center for Scientific Computing (CSC)
> University of Frankfurt
> Max-von-Laue-Straße 1
> 60438 Frankfurt am Main
> +49(0)69/798-47353
> geier_at_[hidden]
> http://csc.uni-frankfurt.de/
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