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Subject: Re: [OMPI users] Open MPI v1.2.5 released
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-01-10 08:17:41

On Jan 9, 2008, at 3:50 PM, Warner Yuen wrote:

> Thanks to Brian Barrett, I was able to get through some ugly Intel
> compiler bugs during the configure script. I now have OMPI v1.2.5
> running nicely under Mac OSX v10.5 Leopard!


> However, I have a question about hostfiles. I would like to manually
> launch MPI jobs from my headnode, but I don't want the jobs to run
> on the head node. In LAM/MPI I could add a "hostname schedule=no" to
> the hostfile, is there an equivalent in OpenMPI? I'm sure this has
> come up before, but I couldn't find an answer in the archives.

Actually, we tried to learn how *not* do to it from LAM :-) and did it
a bit better in Open MPI (at least, we think so ;-) ).

In Open MPI, you can simply not list the head node in the hostfile.
More specifically: in LAM, you *have* to list the node where you
invoke mpirun from in the hostfile (hence the need for the schedule=no
attribute). In Open MPI, there is no such requirement, so you can
just lead the head node's hostname out of the hostfile.

Jeff Squyres
Cisco Systems