在即時系統中，硬即時任務（不接受逾期發生）需要特別的排程器，先討論目前在硬即時排程器中所使用的排程演算法：RM、DM、EDF、LST。再進一步針對 EDF 所衍生的排程演算法做詳細的分析、討論，並提出一種我們改良的排程演算法。 我們實作一個排程模擬器並且用此模擬器來分析EDF 所衍生的排程演算法與我們的方法，最後分別將各排程演算法實作於嵌入式即時系統中，分析結果。 透過在排程模擬器和嵌入式即時系統的排程結果，我們的方法可以維持 Preemptive EDF scheduling 一樣的optimal，也同時因為降低Preemptive EDF scheduling 的overheads，使得feasibility 的成功機率會高於Preemptive EDF scheduling。 In a Real-Time system, hard Real-Time tasks (do not accept delay) need a special scheduler. To discuss current hard Real-Time schedulers which are RM, DM, EDF, LST. We focus on different derived EDF scheduling algorithms. Then we propose a hybrid cooperative and preemptive EDF scheduling algorithm. A detailed analysis on those EDF scheduling algorithms by using our scheduler simulator and a Real-Time embedded system verifies our proposed solution. According to results of our scheduler simulator and a Real-Time embedded system, our solution remains optimal as Preemptive EDF scheduling. And because our solution''s overheads are less than Preemptive EDF scheduling algorithm''s overheads, so ratio of feasibility of our solution is better than ratio of feasibility of Preemptive EDF scheduling.
