Re: [Valgrind-users] OpenMP and Valgrind

[Charles S. <sh...@ll...>]

 From what I've seen Valgrind does work for OpenMP codes built with the 
Intel compilers, with the (minor) exception that a couple of pthreads calls 
used by OpenMP are ignored or kludged, for instance:

==18243== valgrind's libpthread.so: IGNORED call to: pthread_attr_destroy

==18243== valgrind's libpthread.so: KLUDGED call to: pthread_cond_destroy

This doesn't hinder the app's progress, though I wonder whether leaks will 
be misreported since pthread_attr_destroy is ignored.  Maybe this is 
documented somewhere and I just am unaware of it.

Also, in my experience a code that originally ran with 2 threads on 2 cpus 
is about 450x slower under valgrind, so it would be tough applying valgrind 
to a long-running code.

BTW, I wouldn't say that OpenMP or the codes it's used in are by definition 
dusty -- it's a big SMP parallelization timesaver and is in wide use here 
at LLNL and at other facilities that have compute-intensive scientific 
codes.  Physicists would much prefer to sprinkle pragmas rather than having 
to fuss with mutexes and semaphores and attribute objects.  It's true that 
it's an additional layer of abstraction, but so is C over assembler.

Regards-
Charles
______________________________
Charles Shereda
Computation Department
Lawrence Livermore National Lab

At 11:28 AM 7/3/2003 -0700, Dan Kegel wrote:
>Charles De Lean wrote:
>>Has anyone tried using Valgrind on a program using the Intel
>>implementation of OpenMP on Linux?
>
>99.9% of us hackers haven't paid any attention to OpenMP,
>since OpenMP's whole goal is to shield programmers from the
>kind of details us hackers love.  (It's for C or Fortran programmers
>trying to use more than one CPU on their dusty decks of
>punchcards by sprinkling a few pragmas around the loops they
>want parallelized.)
>And I suspect Intel's OpenMP implementation isn't free,
>so that makes it even less likely anyone here's tried it.
>
>There is one free C compiler that implements OpenMP,
>OdinMP.  It lives at http://odinmp.imit.kth.se/ and looks
>like it'd be easy to try.
>See also http://savannah.nongnu.org/projects/gomp/
>- Dan
>
>--
>Dan Kegel
>http://www.kegel.com
>http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045
>
>
>
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