[mpich-discuss] General Scalability Question

Pavan Balaji balaji at mcs.anl.gov
Mon Oct 26 10:52:06 CDT 2009

On 10/26/2009 10:47 AM, Robertson, Andrew wrote:
> Dave,
> So does that imply you wrote the app from square one to use shared
> memory? Or is that part of how mpi gets invoked. One of my applications
> (GASP) uses lam-mpi. And it appears that I get only one mpi process per
> node with multiple application instances.
> Is this accomplished via the use of the "nemisis" or "mt" channel?

Yes. Most MPI implementations do this automatically. You can treat each
core as a different node as far as the application is concerned. The MPI
implementation will internally optimize the rest for you (shared memory
communication within the node and network connection outside).

 -- Pavan

Pavan Balaji

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