Hybrid Multiprocessing in OPTIMUL: A Multiprocessor for Distributed and Shared Memory Multiprocessing with WDM Optical Fiber Interconnections

We present the key features of OPTIMUL (OPTically /nterconnected Mf/Ltiprocessor) - a multiprocessor architecture that implements a distributed shared memory mechanism using wavelength division multi-plexed (WDM) fiber optic buses. The OPTIMUL architecture also supports distributed memory style multiprocessing using the same high-speed message passing mechanisms that implement distributed shared memory. We show the efficiency of the resulting design by presenting the results of a fairly detailed trace-driven simulation of the performance of the proposed interconnection. We also briefly mention some of the engineering issues involved in the design of the WDM fiber bus. Our results seem to indicate that a WDM optical bus with 4 to 5 channels can provide linearly scalable performance for upto 150 CPUs.