Feedback scheduling of real-time control tasks in power-aware embedded systems

Power awareness has become a critical issue in real-time scheduling of embedded systems. In the context of control applications, the goal of high control performance and low energy consumption are at odds with each other. While dynamic voltage/frequency scaling (DVS) has proved to be promising in energy saving while preserving task schedulability, traditional DVS algorithms use either open loop or ad hoc solutions, and hence cannot perform well for dynamic systems where the workload varies significantly. By targeting these systems, a novel scheme, namely DVS-FS, which combines DVS and feedback scheduling, is suggested. The objective is to save CPU energy as much as possible, while still providing control performance guarantees, which largely depends on successful schedule of the control task set. DVS-FS exploits feedback control methodology, and facilitates tradeoffs between energy consumption and control performance through controlling the CPU utilization at a considerably high level. Simulation experiments demonstrate that DVS-FS can easily reduce significant energy consumption at the expense of only minor control performance degradation.