Processor Voltage Scheduling for Real-Time Tasks with Non-Preemptible Sections

As mobile computing is getting popular, there is an increasing interest in techniques that can minimize energy consumption and prolong the battery life on mobile devices. Processor voltage scheduling is an effective way to reduce energy dissipation by reducing the processor speed. In this paper, we study voltage scheduling for real-time periodic tasks with non-preemptible sections. Three schemes are proposed to address this problem. The static speed algorithm derives a static feasible speed based on the Stack Resource Policy (SRP). As worst-case blocking does not always occur, the novel dual speed algorithm switches the processor speed to a lower value whenever possible. The dynamic reclaiming algorithm deploys a reservation-based approach to reclaim unused run time for redistribution. It effectively decreases the processor idle time and further reduces the processor speed. The feasibility conditions are given and proved. Simulation results show that the two dynamic algorithms can reduce processor energy consumption by up to 80 percent over the static speed scheme.