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Subject: Re: [OMPI devel] memchecker and weak symbols
From: Shiqing Fan (fan_at_[hidden])
Date: 2008-02-15 05:35:25


Hi George,
 
> It turned out that memchecker break our usage of weak symbols. The
> problem is that the definition of the weak symbol should always appear
> before the first use of the function. There are two MPI functions that
> are used in the memchecker.h file: MPI_Type_get_contents and
> MPI_Type_get_envelope. The memchecker.h header get included before we
> get a chance to define the #pragma weak, and the symbols are
> incorrectly marked in the resulting object file.
>
> Additionally, I remember that we decided not to use any MPI level
> functions inside the Open MPI library. I guess the correct way of
> doing this is to use directly the functions provided by the datatype
> engine ompi_ddt_get_args once with which set to zero (to retrieve the
> values i.e. similar to MPI_Type_get_envelope) and once with "which"
> set to one (to retrieve the content i.e. similar to
> MPI_Type_get_content).
Yes, you are correct. This has been fixed with r17469. Thanks a lot. :-)

> Moreover, there is a better way to have the memchecker_call function
> implemented by taking advantage of the data-type engine. It will make
> memchecker really dependent of Open MPI ... but I guess not more than
> it is right now :) Ping me if you are interested in exploring this
> option.
That sounds nice, I'm very interested, could you explain a little bit
more in detail?

Thanks,
Shiqing

-- 
--------------------------------------------------------------
Shiqing Fan                     
http://www.hlrs.de/people/fan
High Performance Computing            Tel.: +49 711 685 87234
   Center Stuttgart (HLRS)            Fax.: +49 711 685 65832
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