A NOC closed-loop performance monitor and adapter

In a NoC, the amount of buffers allocated to each communication channel has a significant impact on performance and power consumption. Moreover, since there will be changes in the application communication pattern, or even because a new application is loaded in a SoC, a design based on the worst case scenario will probably either oversize buffers, with obvious power implications, or the performance will be compromised, since not enough buffers will be available. A runtime mechanism is required to automatically adapt the buffer size as a function of the communication pattern. This paper proposes a control mechanism to resize the buffer of an adaptive router. The runtime mechanism is able to monitor the traffic behavior and to control, for each channel, the required buffer size of the adaptive router. Besides, as the complexity of designs increase and technologies scale down, devices are subject to new types of malfunctions and failures. Network-on-chip routers are responsible to ensure the proper communication of on-chip cores, and the buffers present in the router channels are crucial to ensure the communication performance. This way, a technique to isolate faulty buffers is also presented. Experimental results using the proposed architecture have shown that, in the absence of faults, the latency has been decreased by 80%, and throughput has been increased by 45%, in the worst case. In the presence of faults, the proposed architecture was able to sustain the same performance of the equivalent homogeneous router, but with up to 25% power savings.