Errata: MPI Unified window clarification

[jeffhammond]

Problem

The MPI-3.0 standard page 436, lines 37-41, says the following:

In the RMA unified model, public and private copies are identical and updates via put or accumulate calls are eventually observed by load operations without additional RMA calls.

This implies that MPI_WIN_SYNC call is not necessary for unified windows since those windows are identical. The intention of the working group was that the storage used by the window is unified, but the accesses might still need to be synchronized across PUT/GET and load/store or load/store between processes on shared memory.

Proposal & Changes to the Text

Modify the following text on page 436, lines 37-41:

In the RMA unified model, public and private copies are identical and updates via put or accumulate calls are eventually observed by load operations without additional RMA calls.

with

In the RMA unified model, public and private copies are eventually synchronized at a byte-level granularity without additional RMA calls.

Impact on Implementations

None

Impact on Users

None

References

Old ticket: https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/436