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题名:
开放式实时系统的调度方法研究
作者: 邹勇
答辩日期: 2003
专业: 计算机软件与理论
授予单位: 中国科学院软件研究所
授予地点: 中国科学院软件研究所
学位: 博士
关键词: 开放式实时系统 ; 调度 ; 实时操作系统 ; 自适应调度 ; 截止期错过率 ; 硬实时 ; 软实时
其他题名: Research on Scheduling for Open Real-Time Systems
摘要: 实时系统主要面向现实世界中与时间因素相关的应用需求,它所关注的不仅是计算结果在逻辑上的正确性,而且还有输出结果时间的及时性。目前,实时系统已广泛应用在军事和民用领域。然而,随着实时一系统应用的不断深入发展,多类型的硬实时、软实时与非实时任务共存于同一系统中的情况越来越普遍,造成了应用需求的复杂度不断提高。开放式实时系统的概念即是钊一对这种实际情况被提出。本文对开放式实时系统的调度方法进行了深入研究,提出了一种新的集成调度框架--InSFORT(Integrated SchedLlling Framework for Open Real-Time System);在此基础上,提出了开放式实时系统的自适应实时调度方法;结合具体的操作系统平台(Linux),讨论了集成调度框架的设计与实现方案。InSFORT是一种三层结构的实时调度框架,为解决开放式实时系统的多类型任务调度问题而提出。通过把具有某些共同特征的不同方法集成到一个统一的调度框架中,InSFORT可以同时支持多种类型的实时任务以及非实时任务的并发运行。对于在系统中同时运行的非相关的实时或非实时应用程序,可单独进行开发和验证,并可选择不同的局部调度器,再由系统支持它们的统一调度。另外,对开放式实时系统下的服务质量控制也进行了分析,并提供了相应的解决方法。相对于现有的许多方法,该调度框架可支持的任务类型更广泛,并且有良好的可扩展性。针对开放式实时系统对自适应实时调度的需求,首先,提出了面向硬实时应用需求的自适应调度方法,可解决InSFORT中硬实时一应用程序的自适应调度问题;其次,面向软实时应用需求,提出了一种基于模糊控制技术的自适应调度方法,它致力于动态跟踪应用程序的实时性能指标,并把截止期错过率控制在期望值附近。这两种自适应调度方法是与InSFORT紧密结合,可为不同类型的实时任务提供自适应调度支持,主要优点在于可自动调节系统调度的相关部件,使其适应系统内外环境的动态变化。调度方法要在实际中得到应用,需要与具体的操作系统相结合。为达到这个目标,并在实践中检验所提出的理论和方法,我们结合Linux操作系统,设计了InSFORT在一种实时Linux内核中具体实现的方案。该方案以一种双内核的架构和基本的优先级调度为基础,把hiSFORT的各个层次与操作系统的内部功能模块相结合,从而可在操作系统级提供较为完善的、可满足开放式实时系统需求的调度支持。根据此设计方案完成了主要部分的系统实现工作。为检验InSFORT的有效性和实际应用效果,我们利用在Linux上实现的系统,设计了实验方案,进行了一系列实验。实验所获数据表明,开放式实时系统所期望的硬实时、软实时和非实时任务集成调度的目标已经达到,其它实时性能指标也可满足许多实际应用的需要。另外,通过仿真实验对应用模糊控制技术的自适应调度方法进行了检验,结果显示它是有效的,适合解决开放式实时系统中的自适应调度问题。
英文摘要: Real-time systems are mainly designed to satisfy the timing requirements from the real world applications. A real-time system concerns not only the logic correctness of the computing results, but also the time when the results come out. Nowadays, real-time systems have been widely used in military and civilian industry. However, with the development of the real-time system application, the cases that different kinds of hard real-time, soft real-time and non-real-time applications coexist in one system become more and more popular. This situation makes the application requirements become more complex and causes the proposition of the concept of open real-time system. In this thesis, the scheduling problems for open real-time systems are discussed. A new integrated scheduling framework for open real-time system, named InSFORT, is presented. Basing on InSFORT, adaptive real-time scheduling approaches are developed. In the environment of Linux operating system, the design and implement of InSFORT is carried out. InSFORT consists of three levels. It aims to solve the task scheduling problems in open real-time systems. This framework integrates different kinds of scheduling approaches that have some common characteristics, which enables the concurrent running in the case that different kinds of real-time and non-real-time tasks coexist. Furthermore, the quality of service problem is also discussed, and a corresponding solution is presented. Compared with the previous approaches, the advances of this framework are that it can support more kinds of tasks, and its extensibility is better. According to the adaptive scheduling requirements of the open real-time system, adaptive scheduling approaches are presented. Firstly, an approach for the adaptive scheduling of the hard real-time tasks in InSFORT is presented. Secondly, for soft real-time applications, another adaptive scheduling approach is presented. The second one is based on fussy control technology. It can control the deadline missing ratio near the expected value while sampling the applications' performance. These adaptive scheduling approaches are developed for InSFORT, with the merits that they can schedule different kinds of real-time tasks and adapt to the system's dynamic uncertainty through tuning the schedulers. If a scheduling approach would be applied in the real world, it must be implemented in an operating system. For this aim, also in order to test the theories and approaches presented, a scheme is designed for implementing InSFORT in a kind of real-time Linux kernel. This scheme is based on a double-kernel structure and basic priority scheduling. It associates the inSFORT levels and the functions of the Linux kernel, consequently, it can support the scheduling of open real-time systems. According to the design, most of the software implementation works are done. In order to validate the inSFORT and to see its efficiency in the application, experiment schemes are designed, and then perfonned using the implemented system in Linux environment. The results from the experiments show that the expected performance is achieved, and hard real-time, soft real-time and non-real-time tasks in the open real-time system can be integrated and scheduled. Some other performance marks can also satisfy application requirements. Furthermore, by another simulation experiment, the adaptive scheduling approach based on fussy control is validated. The results indicate that it is effective and suitable for the open real-time systems.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.iscas.ac.cn/handle/311060/6310
Appears in Collections:中科院软件所

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Recommended Citation:
邹勇. 开放式实时系统的调度方法研究[D]. 中国科学院软件研究所. 中国科学院软件研究所. 2003-01-01.
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