Underwood, Keith D wrote:

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On the Earth Simulator, there are/were several application codes which are using one-sided communication (instead of 2-sided). They used one-sided communication especially to overlap communication and computation. When I remember correctly, at least one of this applications won a Gordon Bell Award of SC.

The ambiguity of the progress rule notwithstanding, there is no particular reason that one-sided should give you better overlap than two-sided. If this is the reason that people use one-sided, maybe we should revisit the progress rule ;-)

The application codes can overlap communication and computation also for pt2pt on the Earth Simulator. The raw performance of MPI pt2pt and one-sided communication is similar. Which communication is selected, should depend on the application code. And there are application codes which benefit on the one-sided communication model. But the usage of the MPI-2 one-sided library is not zero and one-sided comm is not "always" slower than 2-sided. Hubert PS: Nevertheless, also the Earth Simulator application programmers have asked for simpler synchronization functions for one-sided comms.