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Subject: Re: [OMPI users] trouble using openmpi under slurm
From: David Roundy (roundyd_at_[hidden])
Date: 2010-07-07 13:59:32

On Wed, Jul 7, 2010 at 10:26 AM, Ralph Castain <rhc_at_[hidden]> wrote:
> I'm afraid the bottom line is that OMPI simply doesn't support core-level allocations. I tried it on a slurm machine available to me, using our devel trunk as well as 1.4, with the same results.
> Not sure why you are trying to run that way, but I'm afraid you can't do it with OMPI.

Hmmm. I'm still trying to figure out how to configure slurm properly.
 I want it to be able to put one single-process job per core on each
machine. I just now figured out that there is a slurm "-n" option. I
had previously only been aware of the "-N" and "-c" options, and the
latter was closer match. It looks like everything works fine with the
"-n" option.

However, wouldn't it be a good idea to avoid crashing when "-c 2" is
used, e.g. by ignoring the environment variable SLURM_CPUS_PER_TASK?
It seems like this would be an important feature to be able to use if
one wanted to run mpi with multiple threads per node (as I've been
known to do in the past).

In my trouble shooting, I came up with the following script, which can
reliably crash mpirun (when run without slurm, but obviously
pretending to be running under slurm). :(

set -ev
export SLURM_JOBID=137
export SLURM_NODELIST=localhost
mpirun --display-devel-map echo hello world
echo it worked