[Beowulf] emulating MPI?

Douglas Eadline, Cluster World Magazine deadline at linux-mag.com
Mon Jun 28 12:36:53 PDT 2004

On Mon, 28 Jun 2004, John Wohlbier wrote:

> Hi,
> I'm wondering if there is a way to emulate MPI,
> so that MPI software development may be done on a single
> processor box and run with "virtual nodes."
> Thanks! (Sorry if this is the wrong list for such a question.)

Sure. Both LAM and MPICH (P4 device) start processes that represent
parallel jobs (i.e. usually the -np argument). They also use a "nodes"
file to map the processes to specific nodes in the cluster. (spawning jobs
on other nodes can be done in a variety of ways, ssh, rsh, bps, daemons)  
If your nodes file is one node (localhost), they will all start on the
same node. However, if you program requires a lot of memory, then you will
quickly swamp the single node. If you just want to play with MPI this is
an easy way to do so without having to build/find a cluster. This can be
done for PVM as well.


> jgw
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