實時應用系統可能由功能不相交的任務子集組成，需要操作系統提供分層調度機制。
針對這一問題，提出在μC/OS- Ⅱ實時內核中加入固定時間分配方案來實現兩層的調度策
略。首先擴充了μC/OS- Ⅱ內核任務控制塊數據結構，增加了任務所屬模塊的分層控制信息，再創建一個兩級索引表來實現分層的級聯查找。以原μC/OS-Ⅱ為基礎，開發了分層調度算法的調度器。理論分析和實驗結果表明修改后的算法能對分層子任務進行正確調度，從而完善了μC/OS- Ⅱ實時內核的功能，增強了其對復雜實時應用的支持能力。
關鍵詞：實時系統；分層調度；固定輪轉；μC/OS-Ⅱ
Abstract: Real-time application system may be composed of disjoint task subsets，that needs
layered scheduling mechanism provided by operating system. Aiming at this problem, a scheme of adding fixed time assignment scheme in μC/OS-Ⅱreal-time kernel is proposed to realize two layers scheduling strategies. Firstly, kernel task-control-block (TCB) data structure is expanded. A parameter that used for indicating which sub-modular created task belonging to is added in TCB, and this parameter provide layered control information for scheduling algorithm. Then, two-stage index tables are created to realize layered cascade search. Layered scheduling algorithm is developed based on original μC/OS-Ⅱscheduler. Theoretical analysis and experimental results indicate that the algorithm can scheduling layered subtask correctly , thus further improve the real-time kernel function, enhance supporting ability of μC/OS-Ⅱto complex real-time application system.
Key words: Real-time system; layered scheduling algorithm; fixed-cycle;μC/OS-Ⅱ