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Subject: Re: [OMPI users] Default hostfile not being used by mpirun
From: Ralph Castain (rhc_at_[hidden])
Date: 2011-02-05 20:06:37


The easiest solution is to take advantage of the fact that the default hostfile is an MCA parameter - so you can specify it in several ways other than on the cmd line. It can be in your environment, in the default MCA parameter file, or in an MCA param file in your home directory.

See

http://www.open-mpi.org/faq/?category=tuning#setting-mca-params

for a full description on how to do this.

On Feb 5, 2011, at 3:14 PM, ETHAN DENEAULT wrote:

> Barnet,
>
> This isn't the most straightforward solution, but as a workaround, create a bash script and run that script through npRmpi? Something like:
>
> !#/bin/bash
>
> openmpi -np 15 -hostfile /path/to/hostfile $1
>
> Cheers,
> Ethan
>
> --
> Dr. Ethan Deneault
> Assistant Professor of Physics
> The University of Tampa
> 401 W Kennedy Blvd
> Tampa, FL 33606
> (813) 732-3718
>
> Barnet Wagman <bw_at_[hidden]> wrote:
>
> There have been many postings about openmpi-default-hostfile on the
> list, but I haven't found one that answers my question, so I hope you
> won't mind one more.
>
> When I use mpirun, openmpi-default-hostfile does not appear to get used.
> I've added three lines to the default host file:
>
> node0 slots=3
> node1 slots=4
> node2 slots=4
>
> 'node0' is the local (master) host.
>
> If I explicitly list the hostfile in the mpirun command, everything
> works correctly. E.g.
>
> mpirun -np 15 -hostfile /full/path/to/openmpi-default-hostfile hello_c
>
> works correctly - hello_c gets run using all three nodes.
>
> However, if I don't specify the hostfile, only the local node, node0, is
> used. E.g.
>
> mpirun -np 15 hello_c
>
> creates all 15 processes on node0. I was under the impression that all
> machines listed in openmpi-default-hostfile should get used by default.
> Is that correct?
>
> Unfortunately I can't use the hostfile command line option. I'm going
> to be using a mpi app (npRmpi) that doesn't let me pass params to
> mpirun. So I need all my nodes used by default.
>
> Configuration details:
>
> openmpi 1.4.3, built from source.
>
> OS: Debian lenny (but the Debian openmpi package is NOT installed).
>
> Installation dir: /home/omu/openmpi
>
> The default host file has pathname
> /home/omu/openmpi/etc/openmpi-default-hostfile
>
> I've set two envirnmental variables to support open mpi:
>
> PATH=/home/omu/openmpi/bin:...
> LD_LIBRARY_PATH=/home/omu/openmpi/lib:...
>
>
> Are there any other environmental variables that need to be set?
>
> I'd appreciate any suggestions about this.
>
> thanks,
>
> Barnet Wagman
>
>
>
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