[slurm-users] mpi on multiple nodes

Christopher Samuel chris at csamuel.org
Tue Mar 13 14:17:13 MDT 2018

On 14/03/18 06:30, Mahmood Naderan wrote:

> I expected to see one compute-0-0.local and one compute-0-1.local
> messages. Any idea about that?

You've asked for 2 MPI ranks each using 1 CPU and as you've got 2 cores
on one and 4 cores on the other Slurm can fit both on to one of your
nodes so that's what it's done. This reduces fragmentation of resources
for other jobs that may come later.

If you really want to have a task on each node then you'll need to add:

#SBATCH --ntasks-per-node=1

to your batch file to tell Slurm to only place one task on each node.

Hope that helps!
  Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC

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