[mpiwg-rma] FW: [Mpi3-rma] [EXTERNAL] Re: MPI-3 UNIFIED model updates

Underwood, Keith D keith.d.underwood at intel.com
Wed Aug 28 18:02:25 CDT 2013

> >>> Also, I think we are ignoring the point Jim raised: does OpenSHMEM
> >>> really need these semantics?
> >>
> >> I think this is a grey area of OpenSHMEM and my belief is that it
> >> really does need those semantics.
> >
> >Perhaps this is just an oversight in OpenSHMEM and can be fixed?
> I don't think it's an oversight.  Remember that OpenSHMEM, while a great
> leap forward from SGI's man pages, is still a fairly loose specification.
> There are definitely codes that spin on a completion word (or poll and move
> on to other things, where shmem_wait wouldn't work) in the wild, and
> they're considered correct codes.

And, I think they *should* be correct.  It should be possible in OpenSHMEM and MPI3-RMA-UNIFIED to do shared memory programming using threads locally in the symmetric heap/unified window and have the same mechanisms "just work" when updates from remote accesses arrive.  This provides for an "easy" to access programming model while providing explicit remote memory accesses.

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