實(shí)時應(yīng)用系統(tǒng)可能由功能不相交的任務(wù)子集組成，需要操作系統(tǒng)提供分層調(diào)度機(jī)制。
針對這一問題，提出在μC/OS- Ⅱ?qū)崟r內(nèi)核中加入固定時間分配方案來實(shí)現(xiàn)兩層的調(diào)度策
略。首先擴(kuò)充了μC/OS- Ⅱ內(nèi)核任務(wù)控制塊數(shù)據(jù)結(jié)構(gòu)，增加了任務(wù)所屬模塊的分層控制信息，再創(chuàng)建一個兩級索引表來實(shí)現(xiàn)分層的級聯(lián)查找。以原μC/OS-Ⅱ?yàn)榛A(chǔ)，開發(fā)了分層調(diào)度算法的調(diào)度器。理論分析和實(shí)驗(yàn)結(jié)果表明修改后的算法能對分層子任務(wù)進(jìn)行正確調(diào)度，從而完善了μC/OS- Ⅱ?qū)崟r內(nèi)核的功能，增強(qiáng)了其對復(fù)雜實(shí)時應(yīng)用的支持能力。
關(guān)鍵詞：實(shí)時系統(tǒng)；分層調(diào)度；固定輪轉(zhuǎn)；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