Dynamic Voltage and Frequency Scaling Under a Precise Energy Model Considering Variable and Fixed Components of the System Power Dissipation

This paper presents a dynamic voltage and frequency scaling (DVFS) technique that minimizes the total system energy consumption for performing a task while satisfying a given execution time constraint. We first show that in order to guarantee minimum energy for task execution by using DVFS it is essential to divide the system power into fixed, idle and active power components. Next, we present a new DVFS technique, which considers not only active power, but also idle and fixed power components of the system. This is in sharp contrast to previous DVFS techniques, which only consider the active power component. The fixed plus idle components of the system power are measured by monitoring the system power when it is idle. The active component of the system power is estimated at run time by a technique known as workload decomposition whereby the workload of a task is decomposed into on-chip and off-chip based on statistics reported by a performance monitoring unit (PMU). We have implemented the proposed DVFS technique on the BitsyX platform; an Intel PXA255based platform manufactured by ADS Inc., and performed detailed energy measurements. These measurements show that, for a number of widely used software applications, a total system energy savings of up to 18%, compared to a conventional DVFS technique that considers only variable power, is achieved while satisfying the user-specified timing constraints.