Reducing energy consumption is important for mobile embedded systems and one of its solutions is dynamic voltage scaling (DVS). In this paper, we examine how to achieve further energy saving for periodic real-time tasks with non-preemptible sections on EDF algorithm by using DVS. Previous algorithms use two speed levels to deal with run-time blocking situation. However, this paper proposes a multi-speed algorithm that exploits various speed levels depending on specific blocking situation to minimize energy consumption. Moreover, it also presents an enhanced multi-speed algorithm that further reduces the energy dissipation by dropping the speed level early and considering only remaining blocking time to compute a lower speed. We induced feasibility conditions for our algorithms and proved them. The experiments show that proposed algorithms achieve up to 70.8% energy saving compared to previous algorithms.
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