MANAGING MULTIPLE COMMUNICATION METHODS IN HIGH-PERFORMANCE NETWORKEDCOMPUTING SYSTEMS

Modern networked computing environments and applications often require - or can benefit from - the use of multiple communication substrates, transport mechanisms, and protocols, chosen according to where commun ication is directed, what is communicated, or when communication is pe rformed. We propose techniques that allow multiple communication metho ds to be supported transparently in a single application, with either automatic or user-specified selection criteria guiding the methods use d for each communication. We explain how communication link and remote service request mechanisms facilitate the specification and implement ation of multimethod communication. These mechanisms have been impleme nted in the Nexus multithreaded runtime system, and we use this system to illustrate solutions to various problems that arise when multimeth od communication is implemented. We also illustrate the application of our techniques by describing a multimethod, multithreaded implementat ion of the Message Passing Interface (MPI) standard, constructed by in tegrating Nexus with the Argonne MPICH library. Finally, we present th e results of experimental studies that reveal performance characterist ics of multimethod communication, the Nexus-based MPI implementation, and a large scientific application running in a heterogeneous networke d environment.