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Subject: Re: [OMPI users] OpenMPI on a LAN (Raymond Wan)
From: Ralph Castain (rhc_at_[hidden])
Date: 2008-12-01 10:27:23


Hi Heitor

You may have trouble making this work with OMPI 1.2 depending upon how
you actually execute things. The Publish_name and Lookup_name
functions in that release series are somewhat constrained in their
operation. You may find 1.3 to be a better fit.

That said, you -can- make it work in OMPI 1.2. The key is that both
client and server must be started from the same node - i.e., the
mpirun must be executed on the same node (the proc itself can be
elsewhere). Here is roughly what you have to do for OMPI 1.2:

1. start a persistent orted that will serve as the host for the data:

$> orted --seed --persistent --universe foo

2. start your server off - for this example, I will have it run on a
specified node:

$> mpirun -np 1 -host server-host --universe foo ./my_server &

3. start your client off:

$> mpirun -np 1 -host client-host --universe foo ./my_client &

This will put both client and server in the same "universe", which is
equivalent to being in the same "namespace" - thus, the client should
be able to find the server's published info.

Note that you will have to "kill" the orted when you are done - 1.2
doesn't include a polite way to terminate it, unfortunately.

Of course, you'll still need to solve any ssh issues.

Hope that helps
Ralph

On Nov 29, 2008, at 7:40 AM, Heitor Florido wrote:

> Hi raymond,
>
> I have installed OpenMPI on both computers and my application works
> on on both of them, but when I try to communicate between them, the
> method MPI_Lookup_name can't resolve the name published by the other
> machine.
>
> I've tried to run the example from mpi-forum that uses MPI_Open_port
> too, but it didn't work either.
> After reading about it on some FAQs e some other threads from the
> forum, I believe that I need to config my ssh options.
>
> Heitor
>
>
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