Quarter Load Threshold (QLT) flow control for wormhole switching in mesh-based Network-on-Chip

The fact that latency increases abruptly once the on-chip network is saturated indicates that it is necessary to devise an effective flow control strategy. Through tracing the status of the network buffer space we found that the payload of the on-chip network cannot get beyond an upper bound to avoid vicious congestion. Specifically, quarter of the total network buffer space is such a threshold, which is termed Quarter Load Threshold (QLT). Based on this fact we present the Quarter Load Threshold (QLT) flow control strategy. The performance of the proposed strategy is evaluated by the open source simulator Noxim [Noxim: Network-on-Chip Simulator, http://sourceforge.net/projects/noxim, 2008]. Simulation results show that the on-chip network runs smoothly and no serious congestion is encountered any more.