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题名:
嵌入式操作系统硬实时调度算法的设计与实现
作者: 郭杨
答辩日期: 2007-06-06
授予单位: 中国科学院软件研究所
授予地点: 软件研究所
学位: 博士
关键词: 嵌入式实时操作系统 ; Hopen ; 实时调度 ; 最早截止时间优先 ; 周期性服务器 ; 空闲回收
其他题名: the design and implementation of a hard real-time scheduling algorithm in embedded operating system
摘要: 我国自主研发的嵌入式实时操作系统Hopen,随着其应用领域的不断扩展,系统内核面临着从软实时向实时性要求更高的硬实时的转变。Hopen现有的调度算法是一种简单的基于固定优先级抢占式的软实时调度算法,为了满足硬实时应用的需求,迫切的需要一种高效的硬实时调度算法。 本文提出了一种基于最早截止时间优先(EDF)的周期性服务器调度算法,该算法以EDF调度算法为基础,保证了硬实时作业的时限要求,同时引入了周期性服务器和空闲回收策略,以在不影响实时作业的同时尽快的响应和完成非实时作业。新的调度算法不仅可以很好的应用于硬实时系统而且也同样适用于实时性要求较高的通用系统。 本文首先对该实时调度算法的设计进行了仔细全面的分析。通过周期性任务模型细致的区分了实时系统中存在的各类任务,在传统的EDF算法基础上融入了周期性服务器算法以及空闲回收策略,并提出了服务器参数动态调整概念以及实时性保证措施。其次,本文对调度算法在Hopen内核中的实现进行了详细的说明,其中包括了一些重要数据结构和函数以及高精度定时器的设计并实现。为了在实践中检验调度算法的性能,本文通过在真实环境中的试验,对调度算法的性能进行了全面的测试,获取大量的试验数据,并在分析的基础上得出了结论。最后,对本文所做的工作进行了全面的总结,并对下一步的工作进行了展望。
英文摘要: Hopen is a domestic embedded real-time operating system. As its application domain expands, the kernel of it need to change from soft real-time to hard real-time which has more real-time requirements. The scheduling algorithm of Hopen is a simple preemptive fixed priority driven algorithm and it does not meet highly real-time requirements of hard real-time applications. So an efficient hard real-time scheduling algorithm is required. This dissertation proposes a periodic server scheduling algorithm based on the early deadline first (EDF) algorithm. The scheduling algorithm designed in this dissertation bases on the EDF algorithm to meet deadline requirements of real-time tasks and brings the periodic servers and the slack reclaiming strategy to get rapid response and finish times for non-real-time tasks while not impact the performances of real-time tasks. The new scheduling algorithm can work well not only in hard real-time systems but also in general purpose systems with highly real-time requirements. In this dissertation, firstly, the design of the hard real-time scheduling algorithm is analyzed in details. Through the periodic tasks model, the different types of tasks in the embedded real-time systems are carefully distinguished. The periodic server algorithm and slacks reclaiming strategy are embedded in the traditional EDF algorithm. As followed, the conception of dynamic adjusting periodic servers’ parameters and the guarantee of real-time attributes are also proposed. Secondly, the implementation of scheduling algorithm in Hopen OS kernel is particularly described, including the implementation of many important data structures and functions, and the design and implementation of high precise timers. To get the performances of the scheduling algorithm in practice, necessary tests which are described at the last of the dissertation are carried out in the real circumstance with reasonable conclusions driven from data in tests through comparing and analysis. Finally, the main contribution of this dissertation is summarized and the prospects of following works are looked forward to.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.iscas.ac.cn/handle/311060/6386
Appears in Collections:中科院软件所

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Recommended Citation:
郭杨. 嵌入式操作系统硬实时调度算法的设计与实现[D]. 软件研究所. 中国科学院软件研究所. 2007-06-06.
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