Managing Multiple Communication Methods in High-Performance Networked Computing Systems

Modern networked computing environments and applications often require|or can bene t from|the use of multiple communication substrates, transport mechanisms, and protocols, chosen according to where communication is directed, what is communicated, or when communication is performed. We propose techniques that allow multiple communication methods to be supported transparently in a single application, with either automatic or user-speci ed selection criteria guiding the methods used for each communication. We explain how communication link and remote service request mechanisms facilitate the speci cation and implementation of multimethod communication. These mechanisms have been implemented in the Nexus multithreaded runtime system, and we use this system to illustrate solutions to various problems that arise when implementing multimethod communication. We also illustrate the application of our techniques by describing a multimethod, multithreaded implementation of the Message Passing Interface (MPI) standard, constructed by integrating Nexus with the Argonne MPICH library. Finally, we present the results of experimental studies that reveal performance characteristics of multimethod communication, the Nexus-based MPI implementation, and a large scienti c application running in a heterogeneous networked environment.