Fault-Tolerant Distributed-Shared-Memory on a Broadcast-Based Interconnection Network

The Simultaneous Optical Multiprocessor Exchange Bus (SOME-Bus) is a low-latency, high-bandwidth interconnection network which directly links arbitrary pairs of processor nodes without contention, and can efficiently interconnect over one hundred nodes. Each node has a dedicated output channel and an array of receivers, with one receiver dedicated to every other node's output channel. The SOME-Bus eliminates the need for global arbitration and provides bandwidth that scales directly with the number of nodes in the system. Under the distributed shared memory (DSM) paradigm, the SOME-bus allows strong integration of the transmitter, receiver and cache controller hardware to produce a highly integrated system-wide cache coherence mechanism. Backward Error Recovery fault-tolerance techniques can rely on DSM data replication and SOME-Bus broadcasts with little additional network traffic and corresponding performance degradation. This paper uses extensive simulation to examine the performance of the SOME-Bus architecture under DSM and Backward Error Recovery.