[Mpi3-rma] Alternative Proposal for Shared Memory Support

Torsten Hoefler htor at illinois.edu
Tue Mar 15 23:22:17 CDT 2011

On Tue, Mar 15, 2011 at 09:39:24PM -0500, Rajeev Thakur wrote:
> That's what I meant in my first mail. We need to say whether this example will work or not.
> A=10
> barrier         barrier
>                     x = A
> If not, which synchronization functions need to be used and how? The
> current text does not automatically cover this example.
Right, I never claimed that the proposal is complete :-). It's basically
a quick poll to see if there are major flaws and I should retract or if
it is worth discussing at the Forum (to flesh out such things like you

To answer your question: I think this should either be:

barrier           barrier

This would basically insert a membar in MPI_Win_flush which makes
sure that A is committed before the barrier completes (a barrier flag is
set and read).

This fits our current semantics where we suggest that win_flush can be
used for ordering. Keep in mind that it's still the unified model, i.e.,
the value would commit eventually, the flush is just needed to enforce
ordering with regards to the barrier.

Thanks & Best,

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"A couple of months in the laboratory can frequently save a couple of
hours in the library." - Westheimer (contemporary)

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