Improving the Performance of Regular Networks with Source Routin

Networks of workstations (NOWs) are becoming increas-ingly popular as a cost-effective alternative to parallel com-puters. Network products like Myrinet [1] and ServerNet [8] use the technology developped in parallel computers to compete with other high-speed local area network products. These networks allow the customer to connect processors using irregular topologies, providing the wiring flexibility, scalability, and incremental expansion capability required in this environment. Also, when performance is the primary concern, these network products are being used to build large commodity clusters with regular topologies [12]. In previous papers [5, 6], we have proposed the in-transit buffer mechanism to improve network performance, applying it to NOWs with irregular topology and source routing. This mechanism allows the use of minimal paths among all hosts, breaking cyclic dependencies between channels by storing and later reinjecting packets at some intermediate hosts. In this paper, we apply the in-transit buffer mechanism to regular networks with source routing in order to improve their performance. Also, two path selec-tion policies are evaluated. The first one will always choose the same minimal path from source to destination, whereas the second one will choose from different alternative mini-mal paths in a round-robin fashion. We evaluate by simulation several regular networks with different traffic patterns using timing parameters taken from the Myrinet network. Results show that the overall network throughput can be doubled for large networks.