Limited Preemptive Scheduling

The question whether preemptive systems are better than non-preemptive systems has been debated for a long time, but only partial answers have been provided in the real-time literature, and still some issues remain open. In fact, each approach has advantages and disadvantages, and no one dominates the other when both predictability and efficiency have to be taken into account in the system design. This chapter presents and compares some existing approaches for reducing preemptions and describes an efficient method for minimizing preemption costs by removing unnecessary preemptions while preserving system schedulability.