Technical Report No. 241 - Abstract

T. Zitterell, C. Scholl
Improving Energy-Efficient Real-Time Scheduling by Exploiting Code Instrumentation

Dynamic Frequency and Voltage Scaling is a promising technique to save energy in real-time systems. In this work we present a novel light-weight energy-efficient EDF scheduler designed for processors with discrete frequencies which performs on-line intra- and inter-task frequency scaling at the same time. An intra-task scheduling scheme based on cycle counters of a processor allows the application of our approach to shared code of library functions and to task setups where only sparse intra-task information is available. Our `Intra-Task Characteristics Aware EDF' (ItcaEDF) scheduler which aims to run with a low frequency by eliminating idle time and inter- and intra-task slack times was evaluated in an compiler, WCET analysis, and simulation framework. Our experiments show that state-of-the-art intra-task as well as inter-task frequency scaling approaches are clearly outperformed by our approach.