Integrating Preemption Threshold to Fixed Priority DVS Scheduling Algorithms

Dynamic voltage scaling (DVS) is an effective technique to reduce the energy consumption of CMOS powered embedded systems through software control. However, applying fixed priority DVS algorithms introduces increased number of preemptions, which, in turn results in extra time delay and energy cost. Effectively reducing the number of preemptions is therefore required. In this paper, we propose to integrate preemption threshold to fixed priority DVS scheduling algorithms to reduce such negative impact. Two preemption-aware algorithms ccFPPT and FPPT-WDA are studied. Performance evaluations in terms of both energy consumption and the number of preemptions are conducted among different fixed priority DVS algorithms, with or without preemption threshold. The experimental results show that our algorithms with preemption threshold can save up to 60\% number of preemptions and 20\% energy consumption over existing DVS algorithms.