Jeff Squyres writes that Remote Direct Memory Access (RDMA) is basically a common implementation of a more general concept: RMA (remote memory access), or directly reading and writing to a peer’s memory space:
In general, RMA is a pretty lousy match for MPI’s message-based semantics. Mapping the abstractions provided by RMA concepts to those of two-sided message passing is a complicated process. Indeed, many of the one-sided RMA benefits can be lost when applying them to two-sided communications.
Read the Full Story or check out this presentation from Paul Grun (System Fabrics Works) presenting Dense Clusters Based On RoCE (RDMA over Converged Ethernet).
Recorded at the 2011 OpenFabrics International Workshop.