[Mpi3-rma] MPI-3 UNIFIED model clarification

Jed Brown jedbrown at mcs.anl.gov
Mon Jul 29 17:30:02 CDT 2013

"Sur, Sayantan" <sayantan.sur at intel.com> writes:
> If we require apps working with UNIFIED model to call MPI_Win_sync, an
> one-sided PGAS language might be forced to call sync for any buffer
> that may have been touched remotely. Thereby potentially causing some
> performance degradation.

They need a memory fence anyway on most architectures.

What is the problem with creating a fast path for MPI_Win_sync with
UNIFIED?  Are we crying about 10 cycles (function call/fast path) along
with an explicit statement that (architecture-specific) memory fences
could be used directly if the caller wants that responsibility?
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