[Mpi3-rma] MPI-3 UNIFIED model clarification

[Sur, Sayantan]

> On 07/31/2013 12:00 PM, Jim Dinan wrote:
> > I would bet that past Jim suggested striking the polling/eventually
> > visibile clause and relying on window synchronization to see updates.
> >   :)
> 
> Yup, so did past, present, and future Pavan.  IMO, that's a useless guarantee.
> 
> > The downside to this is that libraries like SHMEM that rely on passive
> > progress and polling, would not be implementable on top of Unified.
> 
> It's pretty useless even for SHMEM, since the user doesn't know when the
> data is valid.  You could poll on a byte for it to turn to one, but at that point
> you only know about that one byte and nothing else.
>

Past Sayantan had missed this discussion, but present Sayantan does agree that "eventually" as defined is useless. But he is also confused by the guarantee given by MPI_Win_flush, that when the call returns, all previously issued RMA ops are complete locally and remotely + UNIFIED (public win == private win).