[Mpi3-rma] Unified model discussion

[Pavan Balaji]

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