Hi Andreas, On Oct 29, 2010, at 12:59 PM, Andreas Kuntze wrote:

Hello all,

in the current MPIT draft, the MPIT_CTRLVAR_WRITE function takes a communicator as an argument. If I understood the description correctly, you have to pass the communicator returned by MPIT_CTRLVAR_GETINFO. Can someone explain to me, for what reason you have to pass it, if you can execute collective write operations on one communicator only for each control variable?

The idea was that the control variable set operation can have a global meaning, in which case it has to be set on all processors of a certain communicator. Passing this communicator into the routine made that explicit (I agree, we could have just made this implicit by using the communicator that is returned by the info call). We discussed this at length at the last face-to-face meeting and actually decided to drop it. The problem that many saw in this was that communicators don't exist before MPI_Init, but we want to be able to call this routine at that time. The compromise was to still return a flag during the info call that says that a variable has a global/collective meaning, but put the burden on the user to ensure that the variable is set consistently across all tasks. This change (along with the other comments I got in the last few meetings), will be reflected in the next MPIT draft. Martin

Thanks,

Andreas _______________________________________________ Mpi3-tools mailing list [email protected] http://BLOCKEDlists.mpi-forum.org/mailman/listinfo.cgi/mpi3-tools

________________________________________________________________________ Martin Schulz, [email protected], http://people.llnl.gov/schulzm CASC @ Lawrence Livermore National Laboratory, Livermore, USA