基于μC/OS-Ⅱ的实时分层调度算法研究

实时应用系统可能由功能不相交的任务子集组成，需要操作系统提供分层调度机制。
针对这一问题，提出在μC/OS- Ⅱ实时内核中加入固定时间分配方案来实现两层的调度策
略。首先扩充了μC/OS- Ⅱ内核任务控制块数据结构，增加了任务所属模块的分层控制信息，再创建一个两级索引表来实现分层的级联查找。以原μC/OS-Ⅱ为基础，开发了分层调度算法的调度器。理论分析和实验结果表明修改后的算法能对分层子任务进行正确调度，从而完善了μC/OS- Ⅱ实时内核的功能，增强了其对复杂实时应用的支持能力。
关键词：实时系统；分层调度；固定轮转；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