Leveraging process variation for performance and energy: In the perspective of overclocking

Process variation is one of the most important factors to be considered in recent microprocessor design, since it negatively affects performance, power, and yield of microprocessors. However, by leveraging process variation, overclocking techniques can improve performance. As microprocessors have substantial clock cycle time margin for yield, there is enough room for performance improvement by overclocking techniques. In this paper, we adopt the F-overclocking technique, which increases clock frequency without changing supply voltage. Our experimental results show that the F-overclocking technique significantly improves performance as well as energy consumption. In addition, the F-overclocking technique is superior to the conventional overclocking technique which increases clock frequency and supply voltage together in the perspective of energy efficiency and reliability, showing similar performance improvement. Furthermore, we propose an adaptive overclocking controller which dynamically applies the F-overclocking technique based on the application characteristics. By adopting our adaptive overclocking controller, we further minimize the reliability loss caused by the F-overclocking technique.