[mpiwg-rma] Single RMA synchronization for several window handles

Rolf Rabenseifner rabenseifner at hlrs.de
Fri Aug 8 09:18:03 CDT 2014


your topic "Reducing Synchronization Overhead Through Bundled
Communication" may get also help if we would be able to 
combine several window handles to one superset window handle.

If you have several windows for different buffers, but
only one synchronization pattern, e.g. MPI_Win_fince
then currently you must call MPI_Win_fence seperately 
for each window handle.

I would propose:

MPI_Win_combine (/*IN*/  int count, 
                 /*IN*/  MPI_Win *win,
                 /*IN*/  MPI_Comm comm, 
                 /*OUT*/ MPI_Win *win_combined)

The process group of comm must contain the process groups of all win.
The resulting window handle win_combined can be used only 
in RMA synchronization calls and other helper routines, 
but not for dynamic window allocation nor for any
RMA communication routine.
Collective synchronization routines must be called by all processes 
of comm.
The semantics of an RMA synchronization call using win_combined
is defined as if the calls were seperately issued for 
each window handle of the array win. If group handles
are part of the argument list of the synchronization call
then the appropriate subset is used for each window handle in win.

What do you think about this idea for MPI-4.0?

Best regards

----- Original Message -----
> From: "Jim Dinan" <james.dinan at gmail.com>
> To: "MPI WG Remote Memory Access working group" <mpiwg-rma at lists.mpi-forum.org>
> Sent: Thursday, August 7, 2014 4:08:32 PM
> Subject: [mpiwg-rma] RMA Notification
> Hi All,
> I have added a new proposal for an RMA notification extension: 
> https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/439
> I would like to bring this forward for the RMA WG to consider as an
> MPI-4 extension.
> Cheers,
>  ~Jim.
> _______________________________________________
> mpiwg-rma mailing list
> mpiwg-rma at lists.mpi-forum.org
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-rma

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: Room 1.307)

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