Deadlock Detection and Recovery for True Fully Adaptive Routing in Regular Wormhole Networks

Deadlock detection and recovery-based routing schemes for wormhole networks have gained attraction because unlike deadlock avoidance-based schemes, they do not restrict routing adaptability. In order to alleviate the overhead of running a recovery procedure, the studies on deadlock detection have focused on the accuracy of deadlock detection, trying to reduce the number of false detections. This paper proposes both deadlock detection and recovery schemes. The proposed detection scheme is based on the turn model and designed to declare only one packet per simple cycle of blocked packets as deadlocked. Our recovery scheme adjusts the time-out value flexibly according to the utilization rate of the recovery resources, rather than fixing a single time-out value as in previous schemes. As a consequence, it not only prevents saturation of the recovery resources by deadlocked packets but also reduces congestion of normal buffers at heavy loads. Simulation experiments show that the proposed deadlock detection scheme significantly reduces the number of false deadlock detections over previous schemes for low to moderate time-out thresholds. It is also found that the proposed recovery scheme prevents overloading of the recovery resources, yielding better network performance.