Rate-based vs delay-based control for DVFS in NoC
Mario R. Casu, Paolo Giaccone · 2015
Minimization of power via DVFS in an NoC is possible, but may result in an intolerable increase of network delay. We examined two DVFS policies, a rate-based policy that scales down frequency and voltage to the minimum value that allows to sustain the injection rate without reaching saturation, and a delay-based policy in which a closed-loop control tunes frequency and voltage such that the NoC average delay tracks a target value. We evaluated the power-delay trade-off by means of network simulations and accurate power estimations after synthesis on a 28-nm FDSOI CMOS technology. Our results over synthetic and multimedia traffic patterns show that the first policy largely pays the better saving in power (20%-50% less than the second policy) with a large network delay increase (up to 3x). We then conclude that the delay-based policy offers a better power-delay trade-off.