Traffic Control in Wormhole-routing Multistage Interconnection Networks

Nonuniform traffic patterns can severely degrade the performance of wormhole-routing multistage interconnection networks in multiprocessor systems. A wormhole-routing switch box architecture is proposed that is able to control the degrading effects of saturation trees on the uniform background traffic under nonuniform traffic patterns that are known a priori. An alternating priority mechanism is introduced for traffic control. It can minimize the length of the hot-spot phase, or, alternatively, suppress any saturation trees and network overloads and minimize the uniform traffic delay under temporary nonuniform traffic scenarios, while it does not degrade performance under pure uniform traffic patterns. It is shown that the alternating priority scheme can effectively control the network performance degradation and that it is able to achieve higher performance as compared to a regular switch box architecture. To account for different application needs, an adaptive transfer mechanism is introduced.