Hybrid earliest deadline first/preemption threshold scheduling for real-time systems

As embedded systems are getting increasingly complex, preemption overheads become a serious load problem for many microchip-based application specific systems, and sometimes may even jeopardize the system schedulability. This paper presents a dynamic preemption threshold scheduling (DPT) that integrates the preemption threshold scheduling into the earliest deadline first The DPT scheduling can effectively reduce context switching by threads assignment and changing the task dynamic preemption threshold at runtime. Meanwhile, because the algorithm is based on dynamic scheduling, it can achieve higher processor utilization with relatively low costs in preemption switching and memory requirements. The DPT scheduling can also perfectly schedule a mixed task set with preemptive and non-preemptive tasks, and subsumes both as special cases.