In the case of SEPARATE, Win_sync will be required to do two things: (1) order load/stores, and (2) synchronize public/private windows. We can as well use Win_sync for unified too, and just get it to do the first part. -- Pavan On 04/02/2011 12:35 PM, William Gropp wrote:

Would that call also complete/order local memory operations (e.g., we could use the same routine)?

Bill

On Apr 2, 2011, at 11:50 AM, Underwood, Keith D wrote:

...

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: [email protected] [mailto:mpi3-rma- [email protected]] On Behalf Of Pavan Balaji Sent: Thursday, March 31, 2011 3:52 PM To: [email protected] 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 _______________________________________________ mpi3-rma mailing list [email protected] http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma

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William Gropp Deputy Director for Research Institute for Advanced Computing Applications and Technologies Paul and Cynthia Saylor Professor of Computer Science University of Illinois Urbana-Champaign

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-- Pavan Balaji http://www.mcs.anl.gov/~balaji