[Mpi3-rma] [EXTERNAL] Re: MPI-3 UNIFIED model clarification

Pavan Balaji balaji at mcs.anl.gov
Sun Aug 4 18:18:33 CDT 2013

On 08/04/2013 06:15 PM, Jed Brown wrote:
> Pavan Balaji <balaji at mcs.anl.gov> writes:
>> SEPARATE is too expensive for such cases.
> What is the lightest weight way for the source to create an ordering at
> the target (which will be using MPI_Win_sync)?  How does the overhead of
> that compare to MPI_Win_sync?

This is not an ordering issue if I'm talking about nonoverlapping 
memory.  If P0 is doing PUTs to P1s memory, and P1 is reading some other 
nonoverlapping region of it's own memory, P0 and P1 need to synchronize 
in some way if they use the SEPARATE model (e.g., by using EXCLUSIVE 
locks).  If they used the UNIFIED model, they can do these accesses 
concurrently without any synchronization.

  -- Pavan

Pavan Balaji

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