Performance of Multistage Bus Networks for a Distributed Shared Memory Multiprocessor

A Multistage Bus Network (MBN) is proposed in this paper to overcome some of the shortcomings of the conventional multistage interconnection networks (MINs), single bus and hierarchical bus interconnection networks. The MBN consists of multiple stages of buses connected in a manner similar to the MINs and has the same bandwidth at each stage. A switch 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 bidirectional routing and there exists a number of paths between any source and destination pair. In this paper we develop self routing techniques for the various paths, present an algorithm to route a request along the path with minimum distance and analyze the probabilities of a packet taking diierent routes. Further, we derive a performance analysis of a synchronous packet-switched MBN in a distributed shared memory environment and compare the results with those of an equivalent bidirectional MIN (BMIN). Finally, we present the execution time of various applications on the MBN and the BMIN through an execution-driven simulation. We show that the MBN provides similar performance to a BMIN while ooering simplicity in hardware and more fault-tolerance than a conventional MIN.