Improving the Accuracy of the Leakage Power Estimation of Embedded CPUs
Ting-Wu Chin, Shiao-Li Tsao, Kuo-Wei Hung and Pei-Shu Huang
Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan
ABSTRACT
Previous studies have used on-chip thermal sensors (diodes) to estimate the leakage power of a CPU. However, an embedded CPU equips only a few thermal sensors and may suffer from considerable spatial temperature variances across the CPU core, and leakage power estimation based on insufficient temperature information introduces errors. According to our experiments, the conventional leakage power models may have up to 22.9% estimation error for a 70-nm embedded CPU. In this study, we first evaluated the accuracy of leakage power estimates based on thermal sensors on different locations of a CPU and suggested locations that can reduce the error to 0.9%. Then, we proposed temperature-referred and counter-tracked estimation (TRACE) that relies on temperature sensors and hardware activity counters to estimate leakage power. The simulation results demonstrated that employing TRACE could reduce the error to 3.4%. Experiments were also conducted on a real platform to verify our findings.
Keywords: Leakage power, Modeling, Thermal sensor.
