[mpiwg-tools] [Omp-tools] Tool initialization question

[Schulz Martin]

Oops, my autocomplete caught the old MPI list name.

Please reply to this email not the first one.

Thanks!

Martin


________________________________________________________________________
Martin Schulz, schulzm at llnl.gov, http://scalability.llnl.gov/
CASC @ Lawrence Livermore National Laboratory, Livermore, USA


From:  Schulz Martin <schulzm at llnl.gov>
Date:  Thursday, July 2, 2015 at 9:50 AM
To:  John Mellor-Crummey <johnmc at rice.edu>
Cc:  ext-omptools <omp-tools at openmp.org>, MPI3 Tools Tools
<mpi3-tools at lists.mpi-forum.org>
Subject:  [Omp-tools] Tool initialization question

Hi John,

(I am cc-ing both the MPI and the OMP tool lists, since this affects both ­
sorry for any duplicate emails this will cause)

We had an MPI tools group call this morning and talked once again about tool
initialization. The current proposals for the two standards are currently
different:

In OpenMP, we rely on a known symbol that the OpenMP runtime looks for and
then calls when it is ready to initialize the tool. We talked about this for
MPI, but didn¹t go with it, since this prevents the ability to allow
multiple tools.

We therefore picked an approach where the tool registers itself once it gets
invoked somehow (e.g., in library initialization routines) and then MPI can
do the actual initialization of all registered tools during MPI_Init. This
allows as many tools to register themselves as needed.

However, when I brought this up at the last OMPT call, you mentioned that
this would cause problem with linking since the runtime system may not be
visible, yet, when the registration call gets loaded. When we talked about
this today, it wasn¹t clear to us anymore, though, why this would be a
problem, since the call the registration function simply could load the
runtime (assuming its a shared library). Can you elaborate a bit more of why
this is problematic?

Anyone else remember details on this and wants to comment as well? If the
registration option doesn¹t work is there a third way that we could adopt
for both standards that fulfills all criteria?

Thanks!

Martin


________________________________________________________________________
Martin Schulz, schulzm at llnl.gov, http://scalability.llnl.gov/
CASC @ Lawrence Livermore National Laboratory, Livermore, USA



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