Newsgroups: comp.parallel.mpi
From: salo@mrjones.engr.sgi.com (Eric Salo)
Subject: Re: MPI on Shared Memory Systems
Organization: Silicon Graphics, Inc.  Mountain View, CA
Date: 29 Apr 1996 03:00:55 GMT
Message-ID: <4m1bd7$jfs@murrow.corp.sgi.com>

> 	I am trying to implement and MPI program on the SGI power challenge
> array. What I would like to do is to have some variables common to all
> the processes. I dont want to explicitly pass messages as these variable are
> frequently updated. I would like to have them as shared memory locations
> accessible to all the processors. Is this possible using MPI? If so, how?

This is a rather nasty area. As soon as you teach your application to use
shared variables, you will destroy your portability to any other MPI
implementation. One might also logically ask at this point why bother with
MPI at all once you have this capability in place.

However, ignoring all that, the answer is yes, it should be possible. All
you need to do is set up a shared arena and voila, off you go. Check the
man pages on usinit() and usconfig() for the dirty details on arenas.

Eric Salo         Silicon Graphics Inc.             "Do you know what the
(415)933-2998     2011 N. Shoreline Blvd, 7L-802     last Xon said, just
salo@sgi.com      Mountain View, CA   94043-1389     before he died?"

