Reference Work Entry

Encyclopedia of Parallel Computing

pp 1379-1391

OpenSHMEM - Toward a Unified RMA Model

  • Stephen W PooleAffiliated withOak Ridge National Laboratory
  • , Oscar HernandezAffiliated withOak Ridge National Laboratory
  • , Jeffery A KuehnAffiliated withOak Ridge National Laboratory
  • , Galen M ShipmanAffiliated withOak Ridge National Laboratory
  • , Anthony CurtisAffiliated withComputer Science Department, University of Houston
  • , Karl FeindAffiliated withSGI


OpenSHMEM is a standards-based partitioned global address space (PGAS) one-sided communications library. There is a long-standing and successful family of SHMEM APIs but there is no standard and implementations differ from each other in various subtle ways, hindering acceptance, portability, and in some cases, program correctness. We discuss the differences between SHMEM implementations and contrast SHMEM with other extant libraries supporting RMA semantics to provide motivation for a standards-based OpenSHMEM with the requisite breadth of functionality.

The Message Passing Interface (MPI) [1] is currently the most widely used communication model for large-scale simulation-based scientific parallel applications. Of these applications, a large number rely on two-sided communication mechanisms. Two-sided communication mechanisms require both sides of the exchange (source and destination) to actively participate, such as in MPI_SEND and MPI_RECV. While many algorithms b ...

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