(1+ ) Approximation Clock Rate Assignment for Periodic Real-Time Tasks on A Voltage-Scaling Processor∗

Energy-efficient scheduling is an effective way to balance the system performance and the energy consumption. We design a polynomialtime (1 + )-approximation algorithm to minimize the energy consumption for periodic real-time tasks over such processors, where is the tolerable error given by users (1 ≥ > 0). It provides trade-offs between the user’s tolerable error and the runtime complexity including the time complexity and the memory space complexity. System engineers could trade performance with implementation constraints.