An effective approach to the enhancement of incomplete hypercube computers

Abstract

An incomplete hypercube appears interesting and practical because of its relaxed restriction on the system size. The performance of incomplete hypercubes can be improved considerably by adding extra connections between pairs of nodes. Extra connections are made by utilizing otherwise unused ports left at nodes and, thus, require little additional hardware. While there are numerous ways of making extra connections, the one we considered results in a system that possesses interesting path characteristics. According to these path characteristics, a simple routing algorithm is developed which takes the most advantage of extra connections, and yet prevents traffic congestion and deadlock. When compared with the regular incomplete hypercube, the resulting incomplete hypercube is shown analytically to yield a roughly 50% reduction in diameter and a notable decrease in mean internode distance. Simulation results indicate that the mean latency of messages is reduced by an amount no less than the internode distance decrease, and the degree of reduction becomes larger when the system load grows. This significant reduction in latency could translate to a respectable performance improvement, making the proposed incomplete hypercube attractive.