Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: Re: [OMPI users] Oversubcription for mimd/mpmd mpiruns
From: Ralph Castain (rhc_at_[hidden])
Date: 2013-06-06 12:46:44


On Jun 6, 2013, at 9:29 AM, "Nima Aghajari" <greyy_at_[hidden]> wrote:

> Hello,
> first of all thanks for your reply. I tried specifying the --slot-list option like you proposed. This will unfortunately lead to the same mpirun with 5 cores. Adding another slot-list command for the second program, e.g.
>
> mpirun -np 4 --slot-list 0-3 prog_1 : -np 1 --slot-list 0 prog_2
>
> will actually run on only 4 cores, but now it takes more than triple the time as needed before on 5 cores. I suppose there should be some overhead because of the oversubscription but that definitely seems too much. Any suggestions?

Not really - oversubscription is pretty painful, depending on what mechanism you use to "idle" prog_2. It could be polling if you aren't careful. You also have to see how you are "idling" prog_1 once it completes its task - again, it could be polling hard if it is in a barrier in MPI_Finalize.

> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users