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Subject: Re: [OMPI users] memchecker overhead?
From: Ashley Pittman (ashley_at_[hidden])
Date: 2009-10-26 17:14:23


On Mon, 2009-10-26 at 16:21 -0400, Jeff Squyres wrote:

> there's a tiny/
> small amount of overhead inserted by OMPI telling Valgrind "this
> memory region is ok", but we live in an intensely competitive HPC
> environment.

I may be wrong but I seem to remember Julian saying the overhead is
twelve cycles for the valgrind calls. Of course calculating what to
pass to valgrind may add to this.

> The option to enable this Valgrind Goodness in OMPI is --with-
> valgrind. I *think* the option may be the same for libibverbs, but I
> don't remember offhand.
>
> That being said, I'm guessing that we still have bunches of other
> valgrind warnings that may be legitimate. We can always use some help
> to stamp out these warnings... :-)

I note there is a bug for this, being "Valgrind clean" is a very
desirable feature for any software and particularly a library IMHO.

https://svn.open-mpi.org/trac/ompi/ticket/1720

Ashley,

-- 
Ashley Pittman, Bath, UK.
Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk