Introduction to Feedback Scheduling

Fixed-Priority Scheduling (FPS) and Earliest-Deadline-First (EDF) are the two dominating scheduling algorithms in real-time systems [1]. Over the last few decades, the industry has migrated from using time-triggered cyclic-executives into these more advanced priority-based methods. FPS and EDF work fine in most of the circumstances. However, for FPS, one identified issue is that there are cases in which low-priority tasks could miss deadlines or even starve if tasks with higher-priorities overrun beyond their specified worst-case execution times.