[mpich-discuss] Questions about using valgrind

[Saurabh T]

I was able to build mpich2 with valgrind using --enable-g=dbg,meminit as suggested on:
http://wiki.mcs.anl.gov/mpich2/index.php/Support_for_Debugging_Memory_Allocation.
I have a few questions about this:

1. How to actually run valgrind? Is it
valgrind mpiexec exec
or
mpiexec valgrind exec?

2. Assuming it is the latter, I noticed that it doesnt report errors from mpich2 itself. It does if mpich2 wasnt built with the --enable-g option. Is this the only benefit enable-g provides? In other words, apart from hiding MPICH2 errors, what are the pros of using enable-g vs using valgrind on the default MPICH2 installation? As you can imagine, there are excellent upsides to maintaining just one MPICH2 installation, so if hiding MPICH2 errors is the only upside of separate installs, I'd look at writing a valgrind suppression file. (Please note that the goal is for valgrind to report errors in the application rather than in MPICH2 itself).

Thank you.
saurabh