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Subject: Re: [OMPI users] MPI_THREAD_FUNNELED and enable-mpi-thread-multiple
From: Ralph Castain (rhc_at_[hidden])
Date: 2013-06-14 19:32:38


On Jun 14, 2013, at 9:46 AM, Brian Budge <brian.budge_at_[hidden]> wrote:

> I'd like to bump this question. I also wanted to ask: I've been
> searching the archives, and it seems that in past versions of OMPI,
> only MPI_THREAD_SINGLE was available from the default configuration of
> OMPI. It seems that as long as calls to MPI were serialized, however,
> there were no issues. Is this still the case in 1.6 and 1.7 series?

Should still be true, though I confess I haven't tested it. I know some people who use it that way, though, and it seems to work for them.

>
> Thanks,
> Brian
>
> On Mon, Feb 4, 2013 at 9:09 PM, Roland Schulz <roland_at_[hidden]> wrote:
>>
>>
>>
>> On Mon, Jan 28, 2013 at 9:20 PM, Brian Budge <brian.budge_at_[hidden]> wrote:
>>>
>>> I believe that yes, you have to compile enable-mpi-thread-multiple to
>>> get anything other than SINGLE.
>>
>>
>> I just tested that compiling with enable-opal-multi-threads also makes
>> MPI_Init_thread return MPI_THREAD_FUNNELED.
>> Does enable-opal-multi-threads have any performance impact? According to
>> http://www.open-mpi.org/community/lists/users/2012/10/20587.php
>> enable-mpi-thread-multiple has significant performance impact (at least for
>> IB). But I couldn't find any description of whether this is also true for
>> enable-opal-multi-threads.
>>
>> Also why is enable-opal-multi-threads required for MPI_THREAD_FUNNELED? This
>> was asked before (e.g.
>> http://www.open-mpi.org/community/lists/devel/2010/05/7900.php) but I
>> couldn't find any answer. What does the option change? The README states:
>> "Enables thread lock support in the OPAL and ORTE layers.", but that is not
>> very useful for a user. Also why is it not enabled by default?
>>
>> Roland
>>
>>>
>>>
>>> Brian
>>>
>>> On Tue, Jan 22, 2013 at 12:56 PM, Roland Schulz <roland_at_[hidden]> wrote:
>>>> Hi,
>>>>
>>>> compiling 1.6.1 or 1.6.2 without enable-mpi-thread-multiple returns from
>>>> MPI_Init_thread as provided level MPI_THREAD_SINGLE. Is
>>>> enable-mpi-thread-multiple required even for
>>>> MPI_THREAD_FUNNELED/MPI_THREAD_SERIALIZED?
>>>>
>>>> This question has been asked before:
>>>> http://www.open-mpi.org/community/lists/users/2011/05/16451.php but I
>>>> couldn't find an answer.
>>>>
>>>> Roland
>>>>
>>>> --
>>>> ORNL/UT Center for Molecular Biophysics cmb.ornl.gov
>>>> 865-241-1537, ORNL PO BOX 2008 MS6309
>>>>
>>>> _______________________________________________
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>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
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>>>
>>>
>>>
>>>
>>
>>
>>
>> --
>> ORNL/UT Center for Molecular Biophysics cmb.ornl.gov
>> 865-241-1537, ORNL PO BOX 2008 MS6309
>>
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