From: salo@cray.com (Eric Salo)
Newsgroups: comp.parallel.mpi
Subject: Re: Specifying execution nodes on Origin 2000
Date: 25 Aug 1998 05:18:16 GMT
Organization: Silicon Graphics, Inc.
Message-Id: <6rtheo$4nt$1@walter-fddi.cray.com>
References: <35E1BDE6.1F4D1CA@pppl.gov>


> I'm trying to restrict the execution of my code on the Origin 2000
> to a specific subset of the available nodes in order to make room for
> another user.  According to the SGI documentation, the way to do this
> is to set the environment variable MPI_DSM_MUSTRUN, but I can't find
> any mention of what to set it to.

MPI_DSM_MUSTRUN is a boolean flag; it's either set or it isn't, so
the specific value is unimportant. If you set MPI_DSM_MUSTRUN, you
are instructing the OS not to *migrate* the MPI processes after their
initial placement by the OS.

There is currently no direct support in mpirun for placing processes on
specific nodes. However, if you set MPI_DSM_OFF, you can then use the
dplace tool to get the desired results:

	mpirun -np 4 dplace <dplace_args> a.out

See the dplace man page for more info if you're interested in the
details.

--
Eric Salo      Silicon Graphics      salo@sgi.com