[MPI3 Fortran] Register optimization problems

[Rolf Rabenseifner]

Hi all,

After we have discussed this compile time problem,
for me, it looks like that the current advices 466:26-468:31
are okay but awkward:

   DD(inbuf);
   MPI_routine_with_invisible_buffers();
     /* e.g., MPI_Wait, or MPI_Send/Recv with MPI_BOTTOM */
   DD(outbuf);

I believe that the method of duplicate buffer in MPI I/O split
collective routines
   MPI_File...begin(buf,...);
   MPI_File...end(buf,....);

Is a good idea.
  
I would like to propose:
  - Special additional fortran bindings with one additional buffer
    buffer argument for all MPI_Wait/Test routines.
    In many cases the several calls can be reduced to one call
    with this additional buffer argument.
  - A special MPI Fortran routine for substituting the
    user DD routine above. This is necessary for all the MPI_BOTTOM
    problems.

I would like to add this to MPI-2.2

Is it okay that I open an appropriate ticket with this
proposal that we can discuss it Monday-Wednesday in the MPI-2.2
slots of the meeting?

With this, one of the Fortran problems may be solved better than
in MPI-2.1.

Best regards
Rolf

Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)