[slurm-users] [EXT] Submitting hybrid OpenMPI and OpenMP Jobs

Ozeryan, Vladimir Vladimir.Ozeryan at jhuapl.edu
Fri Sep 22 13:32:15 UTC 2023


I would set "--ntasks"= number of cpus you want use for your job and remove "--cpus-per-task" which would be set to 1 by default.

From: slurm-users <slurm-users-bounces at lists.schedmd.com> On Behalf Of Selch, Brigitte (FIDD)
Sent: Friday, September 22, 2023 7:58 AM
To: slurm-users at schedmd.com
Subject: [EXT] [slurm-users] Submitting hybrid OpenMPI and OpenMP Jobs

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one of our applications need hybrid OpenMPI and OpenMP Job-Submit.
Only one task is allowed on one node, but this task should use all cores of the node.
So, for example I made:


#SBATCH --nodes=5
#SBATCH --ntasks=5
#SBATCH --cpus-per-task=44
#SBATCH --export=ALL

mpiexec PreonNode test.prscene

But the job does not take more than one  thread:

Thread binding will be disabled because the full machine is not available for the process.
Detected 44 CPU threads, 2 l3 caches and 2 packages on the machine.
Number of CPU processors reported by OpenMP: 1
Maximum number of CPU threads reported by OpenMP: 44

Warning: OMP_NUM_THREADS was set to 44, which is higher than the number of available processors of 1. Will use 1 threads now.

What did I wrong?
Does anyone have any idea why OpenMP thinks it can only use one thread per node?

Thanks !

Best regards,
Brigitte Selch

MAN Truck & Bus SE
IT Produktentwicklung Simulation (FIDD)
Vogelweiher Str. 33
90441 Nürnberg


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