EDF-hv: An Energy-Efficient Semi-Partitioned Approach for Hard Real-Time Systems

The shift from uniprocessor to multi-core architectures has made it more difficult to design predictable hard real-time systems (HRTS) and achieving high processor utilization remains a major challenge. As energy efficiency becomes an important design metric in HRTS, most systems use dynamic voltage and frequency scaling (DVFS) to reduce dynamic power consumption when the system is underloaded. However, for many multi-core systems, DVFS is implemented using voltage and frequency islands (VFI), implying that individual cores cannot independently select their voltage and frequency (v/f) pairs, which results in less energy savings when existing energy-aware task assignment and scheduling techniques are used. In this work, we present an analysis of the increase in energy consumption in the presence of VFI. Further, we propose a semi-partitioned approach called EDF-hv to reduce the energy consumption of HRTS on multi-core systems with VFI. Simulation results revealed that when workload imbalance among the cores is sufficiently high, EDF-hv can reduce system energy consumption by 15.9% on average.