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Subject: Re: [OMPI users] Valgrind Warning
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-12-15 09:02:01


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