PERFORMANCE OF MULTISTAGE BUS NETWORKS FOR A DISTRIBUTED SHARED-MEMORY MULTIPROCESSOR

A Multistage Bus Network (MEN) is proposed in this paper to overcome s ome of the shortcomings of the conventional multistage interconnection networks (MINs), single bus, and hierarchical bus interconnection net works. The MBN consists of multiple stages of buses connected in a man ner similar to the MINs and has the same bandwidth at each stage. A sw itch in an MBN is similar to that in a MIN switch except that there is a single bus connection instead of a crossbar. MBNs support bidirecti onal routing and there exists a number of paths between any source and destination pair. In this paper, we develop self routing techniques f or the various paths, present an algorithm to route a request along th e path with minimum distance, and analyze the probabilities of a packe t taking different routes. Further, we derive a performance analysis o f a synchronous packet-switched MBN in a distributed shared memory env ironment and compare the results with those of an equivalent bidirecti onal MIN (BMIN). Finally, we present the execution time of various app lications on the MBN and the BMIN through an execution-driven simulati on. We show that the MBN provides similar performance to a BMIN while offering simplicity in hardware and more fault-tolerance than a conven tional MIN.