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Subject: Re: [OMPI users] How to specify hosts for MPI_Comm_spawn
From: Ralph Castain (rhc_at_[hidden])
Date: 2008-07-28 11:04:08

Take a look at the man page for MPI_Comm_spawn. It should explain that
you need to create an MPI_Info key that has the key of "host" and a
value that contains a comma-delimited list of hosts to be used for the
child processes.

Hope that helps

On Jul 28, 2008, at 8:54 AM, Mark Borgerding wrote:

> How does openmpi decide which hosts are used with MPI_Comm_spawn?
> All the docs I've found talk about specifying hosts on the mpiexec/
> mpirun command and so are not applicable.
> I am unable to spawn on anything but localhost (which makes for a
> pretty uninteresting cluster).
> When I run
> ompi_info --param rds hostfile
> It reports MCA rds: parameter
> "rds_hostfile_path" (current value: "/usr/lib/openmpi/1.2.5-gcc/etc/
> openmpi-default-hostfile")
> I tried changing that file but it has no effect.
> I am using
> openmpi 1.2.5
> CentOS 5.2
> ethernet TCP
> -- Mark
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