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Subject: [OMPI users] Default hostfile not being used by mpirun
From: Barnet Wagman (bw_at_[hidden])
Date: 2011-02-05 16:54:01


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