Increasing the Efficiency of Latency-Driven DVFS with a Smart NoC Congestion Management Strategy

Dynamic Voltage and Frequency Scaling (DVFS) can be a very effective power management strategy not only for on-chip processing elements but also for the network-on-chip (NoC). In this paper we propose a new approach to DVFS in NoC, which combines a congestion management strategy with a feedback-loop controller. The controller sets frequency and voltage to the lowest values that keep the NoC latency below a predetermined threshold. To cope with burstiness and hotspot patterns, which may lead the controller to overdrive the NoC with too high frequencies and voltages, leading to excessive power consumption, the congestion management strategy promptly identifies the flows that caused the abnormal traffic situation and eliminates them from the latency calculation, leading to a significantly higher power saving. Compared to a baseline DVFS strategy without congestion management, our results show that our proposal saves up to 53% more power when bursty or hotspot-based traffic patterns are detected. In addition, since we also apply power-gating to make an efficient use of the network buffers, we achieve an improvement of up to 38% in power savings when no bursts or hotspots are present.