DVFS is a widely used methodology for reducing the power consumption of mobile devices. This scheme involves frequency scaling in accordance with a specific governor and the establishment of an operating voltage to be paired with frequency. Incorporated into the settings for operating voltage is a guardband that ensures safe processor operation even at the worst conditions of on-chip temperature. Typically, the processor temperature remains at a normal range (i.e., not the worst), hence the voltage guardband set to guarantee safe operation is overly protected. In this paper, we propose a temperature-aware DVS (T-DVS) that aggressively reduces voltage guardband. We explore the opportunity to provide minimum operating voltages for frequencies at different temperatures and realize a dynamic voltage control scheme that reduces power consumption. The T-DVS manages temperature so that it remains in the “green zone” where maximum voltage gain is enabled for power-efficient operation. We validate the effectiveness of the T-DVS under various thermal conditions by using mobile application processors and different operating scenarios. Experimental results show that the T-DVS leads to power gain without degrading performance regardless of thermal conditions and chip characteristics. By examining the real-world applications of and off-the-shelf smartphone, we show that the voltage gains generated by the T-DVS results in battery lifetime increment.

Dynamic Voltage and Frequency Scaling (DVFS) is a widely used methodology to reduce the power consumption of mobile devices. This scheme performs frequency scaling in accordance with a specific governor and sets an operating voltage to be paired with the frequency. Temperature is one of the critical parameters affecting device operation. Practically, a guard-band exists in the operating voltage to ensure safe processor operation even at the worst temperature. DVFS can be optimized in terms of operating voltage under nominal conditions. In this paper, we propose a Temperature-aware DVS (T-DVS) that aggressively reduces the voltage guard-band. We explore the opportunity of providing the minimum operating voltages for frequencies at different temperatures and realize a dynamic voltage control scheme to optimize power consumption. The effectiveness of T-DVS is validated under various thermal conditions by using multi-core application processor. We experimentally observe that T-DVS leads to voltage gain without performance degradation regardless of both thermal conditions and chip characteristics. We show by using off-the-shelf smartphones that the voltage gain achieved by the scheme results in battery lifetime increment.