[Mpi3-tools] Signal safety comments in the MPI tool information interface proposal

[Martin Schulz]

Hi Brian,

(I am also cc-ing the MPI-3 tools group)

At the last forum you had some concerns about the text
passage in the MPI_T proposal regarding signal safety.
We have rewritten the text - what do you think about the
advice to implementors below? Does this address your
concerns?

Thanks,

Martin


Sampling based tools rely on the ability to call the MPI
tool information interface, in particular routines to start, stop,
read, write and reset performance variables, from any program
context, including asynchronous contexts such as signal handlers.
MPI implementations should strive, if possible in their particular
environment, to enable these usage scenarios for all or a subset of the
routines mentioned above. If implementing only a subset, the
read, write, and reset routines are typically the most critical
for sampling based tools. An MPI implementation should clearly
document any restrictions on the program contexts in which
the MPI tool information interface can be used. Restrictions
might include guaranteeing usage outside of all signals or
outside a specific set of signals. Any restrictions could be
documented, for example, through the description returned by
\mpifunc{MPI\_T\_PVAR\_GET\_INFO}.


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