Improving the up∗/down∗ routing scheme for networks of workstations

Abstract

Networks of workstations (NOWs) are being considered as a costeffective alternative to parallel computers. Many NOWs are arranged as a switchbased network with irregular topology, which makes routing and deadlock avoidance quite complicated. Current proposals use the up ∗ /down ∗ routing algorithm to remove cyclic dependencies between channels and avoid deadlock. Recently, a simple and effective methodology to compute up ∗ /down ∗ routing tables has been proposed by us. The resulting up ∗ /down ∗ routing scheme makes use of a different link direction assignment to compute routing tables. Assignment of link direction is based on generating an underlying acyclic connected graph from the network graph. In this paper, we propose and evaluate new heuristic rules to compute the underlying graph. Moreover, we propose a traffic balancing algorithm to obtain more efficient up ∗ /down ∗ routing tables when source routing is used. Evaluation results show that the routing algorithm based on the new methodology increases throughput by a factor of up to 2.8 in large networks, also reducing latency significantly.