Towards preemption control using CPU frequency scaling in sporadic task systems

Preemptions in real-time systems scheduling typically lead to variations in task execution times, increase the temporal overhead required for various RTOS related operations and may even cause unschedulability. We examine the preemption behavior of sporadic tasks scheduled under the Fixed Priority Scheduling (FPS) policy, and evaluate the possibility of using CPU frequency scaling for preemption control. We propose an online heuristic-based algorithm, of linear complexity, to control the number of preemptions in a sporadic task system using CPU frequency scaling. Evaluation results show that CPU frequency scaling is an attractive option to control the preemption behavior of real-time sporadic task systems.