Energy-Aware Fixed-Priority Multi-core Scheduling for Real-Time Systems

Multi-core processors are becoming the dominant choice due to energy and thermal considerations, which also applies to embedded and real-time systems. While fixed-priority scheduling with task-splitting in real-time systems are widely applied, current approaches have not taken into consideration energy-aware aspects such as dynamic voltage/frequency scheduling (DVS). In this paper, we propose two strategies to apply DVS to fixed-priority scheduling algorithms with task-splitting for periodic real-time tasks on multi-core processors. We first propose a strategy that does traditional DVS for each processor after scheduling (post-DVS), which ensures all tasks meet the timing requirements on synchronization. We then propose a new strategy, which determines the frequency of each task before scheduling (pre-DVS) according to the total utilization of task-set and number of cores available, so that the system could take full advantage of all the cores. The combination of frequency pre-allocation and task-splitting makes it possible to maximize energy savings with DVS. We perform a series of simulations to compare the performance of each algorithm with two state-of-the-art scheduling algorithms with task-splitting. Simulation results show that the pre-DVS algorithm we proposed has performed satisfactorily on both schedulability and energy consumption in comparison to the previous approaches.