Hi list,

I specified the hosts because mpich2-1.2 did not seem to detect I was using slurm. Not specifying the -hosts parameter made mpiexec launch using slurm, but using host 'localhost' (which is not a slurm compute node).

I have now compiled mpich-3.1 from source, installed it on all nodes in the cluster, and everything works beautifully.
salloc -n 8 mpiexec.hydra -n 1 ./master : -n 7 ./slave

Thank you for the support!

/ Ruben


On Thu, Apr 10, 2014 at 2:24 PM, Kenneth Raffenetti <raffenet@mcs.anl.gov> wrote:
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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--
/ Ruben FAELENS
+32 494 06 72 59