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Subject: Re: [OMPI users] enable-mpi-threads
From: Lenny Verkhovsky (lenny.verkhovsky_at_[hidden])
Date: 2009-07-09 03:35:15


BTW, What kind of threads Open MPI supports ?
I found in the https://svn.open-mpi.org/trac/ompi/browser/trunk/README that
we support MPI_THREAD_MULTIPLE,
and found few unclear mails about MPI_THREAD_FUNNELED and
 MPI_THREAD_SERIALIZED.
Also found nothing in FAQ :(.
Thanks,Lenny.

On Thu, Jul 2, 2009 at 6:37 AM, rahmani <m_rahmani56_at_[hidden]> wrote:

> Hi,
> Very thanks for your discussion
>
> ----- Original Message -----
> From: "Jeff Squyres" <jsquyres_at_[hidden]>
> To: "Open MPI Users" <users_at_[hidden]>
> Sent: Tuesday, June 30, 2009 7:23:13 AM (GMT-0500) America/New_York
> Subject: Re: [OMPI users] enable-mpi-threads
>
> On Jun 30, 2009, at 1:29 AM, rahmani wrote:
>
> > I want install openmpi in a cluster with multicore processor.
> > Is it necessary to configure with --enable-mpi-threads option?
> > when this option should be used?
> >
>
>
> Open MPI's threading support is functional but not optimized.
>
> It depends on the problem you're trying to solve. There's many ways
> to write software, but two not-uncommon models for MPI applications are:
>
> 1. Write the software such that MPI will launch one process for each
> core. You communicate between these processes via MPI communication
> calls such as MPI_SEND, MPI_RECV, etc.
>
> 2. Write the software that that MPI will launch one process per host,
> and then spawn threads for all the cores on that host. The threads
> communicate with each other via typical threaded IPC mechanisms
> (usually not MPI); MPI processes communicate across hosts via MPI
> communication calls. Sometimes MPI function calls are restricted to
> one thread; sometimes they're invoked by any thread.
>
> So it really depends on how you want to write your software. Make
> sense?
>
> --
> Jeff Squyres
> Cisco Systems
>
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