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Subject: Re: [OMPI users] enable-mpi-threads
From: Lenny Verkhovsky (lenny.verkhovsky_at_[hidden])
Date: 2009-07-09 04:29:33


I guess this question was already before
https://svn.open-mpi.org/trac/ompi/ticket/1367
On Thu, Jul 9, 2009 at 10:35 AM, Lenny Verkhovsky <
lenny.verkhovsky_at_[hidden]> wrote:

> BTW, What kind of threads Open MPI supports ?
> I found in the https://svn.open-mpi.org/trac/ompi/browser/trunk/READMEthat 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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>
>