A comparative study of bidirectional ring and crossbar interconnection networks

For distributed shared memory multiprocessors, the choice and the design of interconnection networks have a significant impact, on their performance. Bidirectional ring networks are considered to be physically fast due to the ir simple structure, but topologically slow since their communication laten cy grows proportionally to the number of nodes. In this paper, we will pres ent a quantitative measure to the question of how physically fast a bidirec tional ring has to be to overcome its topologically slow communication late ncy by comparing it to the crossbar, an interconnection network that has op posite characteristics to the ring network. A hybrid method, in which workload parameters extracted from memory traces are given to an analytical model is used for performance evaluation. Our st udy shows for 16 nodes configuration, the performance of two networks are s imilar. For 32 and 64 nodes configurations, the bidirectional ring outperfo rms the crossbar by 21% and 61% respectively, on the average of four parall el applications. (C) 2001 Elsevier Science Ltd. All rights reserved.