Profile-based optimal intra-task voltage scheduling for hard real-time applications

This paper presents a set of comprehensive techniques for the intratask vokage scheduling problem to reduce energy consumption in hard real-time tasks of embedded systems. Based on the execution profile of the task, a voltage scheduling technique that optimally determinqs the operating voltages to individual basic blocks in the task is proposed. The obtained voltage schedule guarantees minimum average epergy consumption. The proposed technique is then extended to solve practical issues regarding transition overheads, which are totally or panially ignored in the existing approaches. Finally, a technique involving a novel extension of our optimal scheduler is proposed to solve the scheduling problem in a discretely variable voltage environment. In summary, it is confirmed from experiments that the proposed optimal scheduling technique reduces energy consumption by 202% over that of one of the state-of-the-art schedulers [I 11 and, funher,'the extended technique in a discrete voltage environment reduces energy consumption by 45.3% on average.