SMART: A scalable mapping and routing technique for power-gating in NoC routers

Reducing the size of the technology increases leakage power in Network-on-Chip (NoC) routers drastically. Power-gating, particularly in NoC routers, is one of the most efficient approaches for alleviating the leakage power. Although applying power-gating techniques alleviates NoC power consumption due to high proportion of idleness in NoC routers, since the timing behavior of packets is irregular, even in low injection rates, performance overhead in power-gated routers is significant. In this paper, we present SMART, a Scalable Mapping And Routing Technique, with virtually no area overhead on the network. It improves the irregularity of the timing behavior of packets in order to mitigate leakage power and lighten the imposed performance overhead. SMART employs a special deterministic routing algorithm, which reduces number of packets encounter power-gated routers. It establishes a dedicated path between each source-destination pair to maximize using powered-on routers, which roughly halves the number of wake-ups. Additionally, in order to maximize the efficiency of the proposed routing algorithm, SMART provides an exclusive mapping for each communication task graph. In proposed mapping, all cores should be arranged with a special layout suited for the proposed routing, which helps us to minimize the number of hops. Furthermore, we modify the predictor of conventional power-gating technique to reduce energy overhead of inconsistent wake-ups. Experimental results on SPLASH-2 benchmarks indicate that the proposed technique can save 21.9% of static power, and reduce the latency overhead by 42.9% compared with the conventional power-gating technique.