On 08/27/2013 12:57 PM, Jeff Hammond wrote:

The MPI standard will not define by what mechanism the SHMEM implementation will establish the necessary consistency. This is what I mean by undefined = implementation-defined. I do not think that Keith is proposing to enumerate all processor memory models and the appropriate fences required to achieve the affect of win_sync but at lower cost. Thus, it is the implementation - or perhaps more accurately, the platform on which the implementation resides - that will define these semantics.

Here's what I understood from Keith -- He wants a statement in the standard that says the application can do platform-specific memory consistency to synchronize the public and private windows in UNIFIED. I do agree that that's a very flimsy statement and doesn't really mean much. But I'm calling it a definition, while I think you are saying that it's pretty much undefined. I like leaving it totally undefined better than the above "definition". -- Pavan -- Pavan Balaji http://www.mcs.anl.gov/~balaji