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Subject: Re: [OMPI users] Valgrind Warning
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2008-12-15 10:59:56


Ok,
thanks a lot,
as soon as possibile, i''install 1.3 version.

But i don't understand why MPI_Recv warnings are detected. Which is
the difference with MPI_Send warnings? Modules involved in OpenMPI are
differents?

2008/12/15 Tim Mattox <timattox_at_[hidden]>:
> Gabriele,
> You should switch the the upcoming v1.3 release as soon as you can,
> via either the v1.3rc2 tarball or one of the v1.3rc3 nightly tarballs,
> available here: http://www.open-mpi.org/nightly/
> We are very close to v1.3, so not much should be different between
> those versions and the final v1.3.
>
> To see why you should switch, read the FAQ entries about Memchecker
> that start here:
> http://www.open-mpi.org/faq/?category=debugging#memchecker_what
>
> On Mon, Dec 15, 2008 at 9:34 AM, Gabriele Fatigati <g.fatigati_at_[hidden]> wrote:
>> PS: i'm using openmpi 1.2.5..
>>
>> 2008/12/15 Gabriele Fatigati <g.fatigati_at_[hidden]>:
>>> Hi Jeff,
>>> i recompiled libibverbs and libmthca with valgrind flas, but for
>>> strage reasons, only warning over MPI_Send are disappears, but
>>> warnings over MPI_Recv remains!
>>>
>>> 2008/12/15 Jeff Squyres <jsquyres_at_[hidden]>:
>>>> Whoops; that was a reply to the wrong message. :-)
>>>>
>>>> You'll need to recompile both libiverbs and libmthca with the valgrind flag,
>>>> and use the enhanced memchecker support in v1.3.
>>>>
>>>> I have not personally verified that all the warnings disappear in this
>>>> configuration (I was hoping to verify this somewhere during the v1.3
>>>> series).
>>>>
>>>>
>>>>
>>>>>
>>>>> On Dec 15, 2008, at 6:37 AM, Gabriele Fatigati wrote:
>>>>>
>>>>>> Hi Jeff,
>>>>>> i recompiled libmthca with --with-valgrind flag, and modified
>>>>>> enviroment variables, but warnings doesnt' disappears..
>>>>>>
>>>>>> 2008/12/14 Jeff Squyres <jsquyres_at_[hidden]>:
>>>>>>>
>>>>>>> On Dec 14, 2008, at 8:21 AM, Gabriele Fatigati wrote:
>>>>>>>
>>>>>>>> i have a strage problems with OpenMPI 1.2.5 Intel Compiled when i
>>>>>>>> debug my code under Valgrind 3.3. In a very simple ping-pong MPI
>>>>>>>> application, i retrieve strange warnings about MPI Communications,
>>>>>>>> like MPI_Send,MPI_Recv. Valgrind tells me that there are uninitialized
>>>>>>>> values in send/recv buffers, but there are initialized, i'm absolutely
>>>>>>>> sure!
>>>>>>>>
>>>>>>>> There warnings are detected when my application runs over Infiniband
>>>>>>>> net,
>>>>>>>
>>>>>>> This is because IB uses memory that does not come from the memory
>>>>>>> allocator
>>>>>>> that Valgrind is aware of (e.g., it may be memory that was allocated by
>>>>>>> the
>>>>>>> kernel itself). Hence, since Valgrind is unaware of the memory, it
>>>>>>> thinks
>>>>>>> that its contents are undefined. As such, it's quite likely that you're
>>>>>>> seeing false positives.
>>>>>>>
>>>>>>> The memchecker support in the upcoming v1.3 series made quite a few
>>>>>>> advancements in the area of valgrind memory checking, and recent
>>>>>>> versions of
>>>>>>> libibverbs allow you to compile in valgrind extensions that tell
>>>>>>> valgrind
>>>>>>> "this memory is ok" (which prevents these false positives). I'm pretty
>>>>>>> sure
>>>>>>> that the OFED install does not enable these libibverbs valgrind
>>>>>>> extensions;
>>>>>>> you will likely need your own installation of libibverbs and your verbs
>>>>>>> plugin (libmthca for you, I think...?) that explicitly has the valgrind
>>>>>>> extensions enabled.
>>>>>>>
>>>>>>> --
>>>>>>> Jeff Squyres
>>>>>>> Cisco Systems
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> users mailing list
>>>>>>> users_at_[hidden]
>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Ing. Gabriele Fatigati
>>>>>>
>>>>>> Parallel programmer
>>>>>>
>>>>>> CINECA Systems & Tecnologies Department
>>>>>>
>>>>>> Supercomputing Group
>>>>>>
>>>>>> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>>>>>>
>>>>>> www.cineca.it Tel: +39 051 6171722
>>>>>>
>>>>>> g.fatigati_at_[hidden]
>>>>>> _______________________________________________
>>>>>> users mailing list
>>>>>> users_at_[hidden]
>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>
>>>>>
>>>>> --
>>>>> Jeff Squyres
>>>>> Cisco Systems
>>>>>
>>>>> _______________________________________________
>>>>> users mailing list
>>>>> users_at_[hidden]
>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>
>>>>
>>>> --
>>>> Jeff Squyres
>>>> Cisco Systems
>>>>
>>>> _______________________________________________
>>>> users mailing list
>>>> users_at_[hidden]
>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> Ing. Gabriele Fatigati
>>>
>>> Parallel programmer
>>>
>>> CINECA Systems & Tecnologies Department
>>>
>>> Supercomputing Group
>>>
>>> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>>>
>>> www.cineca.it Tel: +39 051 6171722
>>>
>>> g.fatigati_at_[hidden]
>>>
>>
>>
>>
>> --
>> Ing. Gabriele Fatigati
>>
>> Parallel programmer
>>
>> CINECA Systems & Tecnologies Department
>>
>> Supercomputing Group
>>
>> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>>
>> www.cineca.it Tel: +39 051 6171722
>>
>> g.fatigati_at_[hidden]
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>
>
>
> --
> Tim Mattox, Ph.D. - http://homepage.mac.com/tmattox/
> tmattox_at_[hidden] || timattox_at_[hidden]
> I'm a bright... http://www.the-brights.net/
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>

-- 
Ing. Gabriele Fatigati
Parallel programmer
CINECA Systems & Tecnologies Department
Supercomputing Group
Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
www.cineca.it                    Tel:   +39 051 6171722
g.fatigati_at_[hidden]