[Mpi3-rma] FW: MPI_Accumulate

[Jeff Hammond]

My understanding has always been that MPI_Accumulate was and is atomic
at granularity of the underlying built-in datatype, as opposed to
byte-wise atomic like MPI_Put.  This is the whole reason that
MPI_Accumulate w/ MPI_REPLACE exists.  Without the additional
atomicity guarantee, that feature would be pointless.

Jeff

On Tue, Oct 2, 2012 at 11:38 AM, Richard Graham <richardg at mellanox.com> wrote:
> resending
>
>
>
> From: Richard Graham
> Sent: Tuesday, October 02, 2012 12:22 PM
> To: MPI 3.0 Remote Memory Access working group
> (mpi3-rma at lists.mpi-forum.org)
> Subject: MPI_Accumulate
>
>
>
> What are the requirements placed on MPI_Accumulate if more than one mpi
> process tries to update the same location ?  Does MPI provide any
> consistency promises, or is it up to the application to guarantee these ?  I
> see that the get accumulate routines are defined to be atomic, but don’t see
> the same requirement for accumulate.
>
>
>
> Thanks,
>
> Rich
>
>
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-- 
Jeff Hammond
Argonne Leadership Computing Facility
University of Chicago Computation Institute
jhammond at alcf.anl.gov / (630) 252-5381
http://www.linkedin.com/in/jeffhammond
https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond