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From: Jeff Squyres \(jsquyres\) (jsquyres_at_[hidden])
Date: 2006-04-30 19:36:17

OMPI will use as many slots as Torque tells it to. So if you qsub with
ppn=2, then OMPI will use 2 slots per node; if you qsub with ppn=1, then
OMPI will use 1 slot per node, etc.

OMPI defaults to -byslot scheduling, so if you qsub with ppn=2/OMPI uses
2 slots per node, OMPI will schedule MPI_COMM_WORLD ranks 0 and 1 on the
first node, 2 and 3 on the next node, etc.

There is not currently any diagnostic output that shows this; I can add
it to my to-do list.

> -----Original Message-----
> From: users-bounces_at_[hidden]
> [mailto:users-bounces_at_[hidden]] On Behalf Of Ogden, Jeffry Brandon
> Sent: Friday, April 28, 2006 6:20 PM
> To: users_at_[hidden]
> Subject: [OMPI users] Default number of slots when using Torque
> How does the orterun launch determine the default number of slots per
> node when running in a Torque job? Is there debug output from orterun
> that will show me this?
> Thanks.
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