Investigating the effect of voltage-switching on low-energy task scheduling in hard real-time systems

We investigate the effect of voltage-switching on task execution times and energy consumption for dual-speed hard real-time systems, and present a new approach for scheduling workloads containing periodic tasks. Our method minimizes the total energy consumed by the task set and guarantees that the deadline for every task is met. We present a mixed-integer linear programming model for the NP-complete scheduling problem and solve it for moderate-sized problem instances using a public-domain solver. For larger task sets, we present a novel extended-low-energy earliest-deadline-first (E-LEDF) scheduling algorithm and apply it to two real-life task sets. Our results show that energy can be conserved in embedded real-time systems using energy-aware task scheduling. We also show that switching times have a significant effect on the energy consumed in hard real-time systems.