[Mpi3-rma] Unified model discussion

[Underwood, Keith D]

That is an important point.  What if we allow unified to work for this use case without additional calls, but add a call to force synchronization when the local and remote accesses would conflict?

Keith

> -----Original Message-----
> From: mpi3-rma-bounces at lists.mpi-forum.org [mailto:mpi3-rma-
> bounces at lists.mpi-forum.org] On Behalf Of Pavan Balaji
> Sent: Thursday, March 31, 2011 3:52 PM
> To: mpi3-rma at lists.mpi-forum.org
> Subject: [Mpi3-rma] Unified model discussion
> 
> 
> When we were having the discussion on the unified model during the last
> working group meeting, I forgot to point out one important use case:
> 
> Process 0
> ----------
> Win_lock(shared, P0)
> load(A)
> store(B)
> Win_unlock
> 
> Process 1
> ---------
> Win_lock(shared, P0)
> Put(C)
> Get(D)
> Win_unlock
> 
> That is, two processes are reading/writing to different parts of the
> window. This is an important model and can only be supported in
> unified,
> not separate (because of potential cache-line false sharing).
> 
> So, basically, no we cannot remove the unified model in spite of all
> its
> nonsense with load/store ordering.
> 
>   -- Pavan
> 
> --
> Pavan Balaji
> http://www.mcs.anl.gov/~balaji
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