Performance Comparison of Wormhole-Routing Priority Switch Architectures

− Temporary nonuniform traffic patterns can severely degrade the performance of wormholerouting multistage interconnection networks in multiprocessor systems. Temporary saturation trees build up inside the network under these traffic patterns that result in a temporary network overload with increased packet delay. Recently, enhanced switch box architectures and priority mechanisms were proposed that are able to alleviate or control the degrading effects of these saturation trees. In this paper, it is studied how these different mechanisms influence the lengths of hot-spot and overload phases, and message delay. All mechanisms are able to alleviate performance degradation. The switch box design proposed in [9] in conjunction with an alternating priority mechanism is able reduce network overload and message delay the most while the hot-spot phase is increased moderately only. This can be achieved with low hardware overhead.