Transferring performance gain from software prefetching to energy reduction

Performance-enhancement techniques improve CPU speed, but at higher cost to other valuable system resources such as power and energy. We study this trade-off using software prefetching as the system performance-enhancement technique. We first demonstrate software prefetching provides an average 36% performance boost with 8% more energy consumption and 69% higher power on six memory-intensive benchmarks. However, when we combine prefetching with a (unrealistic) static voltage scaling technique, the performance gain afforded by prefetching can be traded off for savings in power/energy consumption. In particular, we observe a 48% energy saving when we slow down the system with prefetching so as to match the performance of the system without prefetching. This suggests a promising approach to build low power systems by transforming traditional performance-enhancement techniques into low power methods. We thus propose a real time dynamic voltage scaling (DVS) algorithm that monitors a system´s performance and adapts the voltage level accordingly while maintaining the observed system performance. Our dynamic DVS algorithm achieves a 38% energy saving without any performance loss on our benchmark suite.