Re: [BProc] Valgrind and BProc (again)

[Erik H. <eah...@gm...>]

On 6/16/05, Julian Seward <ju...@va...> wrote:
>=20
> Valgrind is a GPL'd tool suite for doing memory debugging and profiling
> on x86-linux and amd64-linux.  We are looking into the issue of making
> Valgrind work well on BProc and hence on MPI.
>=20
> I'd like to re-ask Ceri's question: has anyone used or tried to use
> Valgrind over BProc?  If so, what did you have to do to make it work?

I've never tried to use it in this manner.  I did take a quick peek at
this once a while back.  At the time it looked to me like starting a
process with valgrind was (essentially) setting LD_PRELOAD to load the
valgrind .so files and maybe a few other environment variables.  Is
this still more or less what valgrind is doing?  /usr/bin/valgrind I
found on my system here is just a binary.

If it is....   then it seems to me the best way to get it started
would be to get the same variables set for the processes running out
on the nodes.  The following would be required to get that done, I
think:

1. Valgrind has to have some reasonably nice mechanism to tell us what
exactly needs to be set.  I'm not sure exactly what that should look
like but I figure there's lots of possibilities.

2. mpirun, bpsh, et al. need a mechanism to have different environment
variables set for the child processes.  That's easy but it's not there
at this point.

3. The valgrind libraries need to be available on the slave nodes.=20
This is just a system configuration issue.  I did some work
experimenting with migration after linking so this requirement could
potentially go away.

What do you think?

- Erik

> > From: Cerion Armour-Brown <cerion@op...>
> > Subject: valgrind & bproc
> > Date: 2005-05-30 01:40
> >   Hi,
> > I"m a developer working on Valgrind, and I"m trying to work out the bes=
t way
> > to use valgrind with bproc.
> >
> > Does anyone already do this?  (Directly with bproc - not via mpi).
> > If so, I"d really appreciate some details on how you"ve set this up.
> >
> > I understand that using valgrind with mpirun is fairly straightforward
> >(though
> > I haven"t set up mpi yet to try it out).  From what I"ve read, it seems
> > valgrind must be accessible from the nodes (nfs, or whatever), but the
> > program to run is migrated from the master, yes?
> >
> > Using bpsh, I don"t see how I can avoid needing both valgrind, and the
> >program
> > to run, accessible from the nodes, since running
> > $ bpsh -a valgrind foo
> > will migrate valgrind, then, on the nodes, valgrind will look for foo.
> > Valgrind is unlike gdb in that you cannot "attach" it once the program =
has
> > started.  So the trick used for gdb (bpsh -a foo, find foo"s pid, attac=
h
> >gdb)
> > won"t work.
> >
> > Any pointers much appreciated,
> > Cerion
>=20
>=20
>=20
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