What version of mpich are you using? Why are you specifying -hosts in your mpiexec command? Are you allocating resources in some other way prior to launching your job? You are correct about the normal behavior of hydra. It launches a proxies on all nodes which then launch the MPI processes. On 04/10/2014 06:49 AM, Ruben Faelens wrote:

Hello list,

I have been messing around with SLURM and MPICH2 for about a week now, in order to run NONMEM on my cluster.

I start my job using the following command line:

...

mpiexec.hydra -hosts node2-a,node2-b -bootstrap slurm -rmk slurm -n 1 ./master : -n 7 ./slave

Using pstree, I can see that this launches the following command:

...

srun -N 4 -n 4 /usr/local/bin/hydra_pmi_proxy --control-port node2-head:38860 --rmk slurm --launcher slurm --demux poll --pgid 0 --retries 10 --usize -2 --proxy-id -1

Apparently, Hydra launches one single 'hydra_pmi_proxy' per node, after which the hydra_pmi_proxy launches the other processes. This completely screws up allocation rules in SLURM.

Is this normal behaviour? I would rather have mpiexec.hydra allocate the right number of resources on SLURM, instead of seemingly deciding on its own which hosts to use.

Kind regards, Ruben FAELENS

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