A comparison of adaptive wormhole routing algorithms

• Published in: International Symposium on Computer Architecture: Proceedings of the 20th annual international symposium on Computer architecture; 16-19 May 1993 pp. 351 - 360
• Main Authors: Boppana, Rajendra V., Chalasani, Suresh
• Format: Conference Proceeding
• Language: English
• Published: New York, NY, USA ACM 01.05.1993
• Series: ACM Conferences
• Subjects: Computer systems organization > Architectures > Parallel architectures; Networks > Network types; Theory of computation > Design and analysis of algorithms > Approximation algorithms analysis > Routing and network design problems; wormhole routing; multicomputer networks; adaptive routing; message routing; k-ary n-cubes; deadlocks; store-and-forward routing
• ISBN: 0818638109; 9780818638107
• DOI: 10.1145/165123.165177

Improvement of message latency and network utilization in torus interconnection networks by increasing adaptivity in wormhole routing algorithms is studied. A recently proposed partially adaptive algorithm and four new fully-adaptive routing algorithms are compared with the well-known e-cube algorithm for uniform, hotspot, and local traffic patterns. Our simulations indicate that the partially adaptive north-last algorithm, which causes unbalanced traffic in the network, performs worse than the nonadaptive e-cube routing algorithm for all three traffic patterns. Another result of our study is that the performance does not necessarily improve with full-adaptivity. In particular, a commonly discussed fully-adaptive routing algorithm, which uses 2n virtual channels per physical channel of a k-ary n-cube, performs worse than e-cube for uniform and hotspot traffic patterns. The other three fully-adaptive algorithms, which give priority to messages based on distances traveled, perform much better than the e-cube and partially-adaptive algorithms for all three traffic patterns. One of the conclusions of this study is that adaptivity, full or partial, is not necessarily a benefit in wormhole routing.