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Subject: Re: [OMPI users] Valgrind Warning
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2008-12-15 09:34:32


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]