Power Consumption Modeling for DVFS Exploitation

A lot of task scheduling algorithms and power management policies have been developed based on simplistic power models, which rarely take into account the effects of the power consumptions of the different components of a real system. Most of the models on which the study of the DVFS scheduling is based, make the assumption that the power consumption of a processor could be modelled as a E ∝ V 2 model. This hypothesis, even if partly true, is not generally applicable when considering the complete system, which consists of the processor, memories and power conversion circuits. In this paper we present a power and energy model for a DVFS enabled mobile computing platform. The platform is based on a low power SoC, which integrates both the processor core and memory, as well as other hardware accelerators. We include in our analisys the study of the power conversion components, which supply the SoC. Starting from measures, we first characterize the power consumption of the SoC and the converters, then a power and energy model for the processor is proposed. The model is able to predict the power consumption of the processor core with an average error less than 10%. This is then used to analyse two DVFS scheduling techniques based on the EDF algorithm, Cycle Conserving and Look Ahead. The results show that the CPU energy saving computed using our model, is far less than what would be expected using a model that does not take into account the effect of the static power.