Analysis of true fully adaptive routing with software-based deadlock recovery

Several analytical models of fully adaptive routing (AR) in wormhole-routed networks have recently been reported in the literature. All these models, however, have been discussed for routing algorithms with deadlock avoidance. Recent studies have revealed that deadlocks are quite rare in the network, especially when enough routing freedom is provided. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated researchers to introduce fully adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model of a true fully AR algorithm with software-based deadlock recovery, proposed in Martinez et al. (Software-based deadlock recovery techniques for true fully AR in wormhole networks, Proc. Int. Conf. Parallel Processing (ICPP'97), 1997, p. 182) for k-ary n-cubes. The proposed model uses the results from queueing systems with impatient customers to capture the effects of the timeout mechanism used in this routing algorithm for deadlock detection. Results obtained through simulation experiments confirm that the model predicts message latency with a good degree of accuracy under different working conditions.