Performance of Chaos and Oblivious Routers under Non-uniform Trac

Chaos router is a nonminimal adaptive packet router that is both deadlock free and probabilistically livelock free [Kon91]. Unlike its predecessors [Nga89], the Chaos router uses randomization to provide an e cient way to avoid livelock [KS90]. The Chaos router has been compared in software simulation studies to the state-of-the-art oblivious routers (i.e. dimension order routers) on the hypercube topology [KS91], and the mesh and torus topologies [BS92]. The results, based on simulations of two di erent workloads, one uniform and one non-uniform load, show that in general the Chaos router is superior to the oblivious router. However, two workloads alone are not representative of the typical types of tra c encountered in practice. In this paper ve additional non-uniform workloads are simulated. Each was chosen to represent one of the various types of communication encountered in typical programs. The workloads, compared on both the 256 node torus and hypercube topologies, show considerable variety and reveal insight on the e ectiveness of Chaotic adaptive routing on non-uniform loads. Data presented includes the saturation point of the networks under the various loads, the throughput as a function of presented load, latency, and total delay of packets through the network. Collectively, this data gives a much clearer and complete characterization of the Chaos and oblivious routers' behavior on non-uniform tra c.