A PERFORMANCE EVALUATION OF ADAPTIVE ROUTING IN BIDIMENSIONAL CUT-THROUGH NETWORKS

Abstract

The performance of the communication network of a massively parallel processor depends, among other parameters, on the network topology, the message flow control and the routing mechanisms. This paper analyses the gains in average message latency and maximum sustained throughput that can be achieved using an adaptive routing strategy instead of an oblivious one. Two different bidimensional topologies have been studied, mesh and torus, using cut-through message flow control. First, we have simulated an ideal case in which there is no limit to the temporary storage capacity of the routing node. Then, a more realistic design, that implies the implementation of a deadlock avoidance technique, is analysed. To assure deadlock-free routing, the network is split into several virtual networks. Results show that adaptive routing is not a good election with this kind of networks. The torus topology shows potentially better results than the mesh. In any case, a different deadlock avoidance technique should be implemented if these potential gains are to be exploited.