【作者】 周丹；

【导师】 杨斌；

【作者基本信息】 西南交通大学 ， 计算机应用技术， 2005， 硕士

【摘要】 随着以计算机技术、通讯技术、消费电子技术为主的IT产业的快速发展,嵌入式系统得到了越来越广泛的应用。在包括科学研究、工程设计、军事技术、商业娱乐及人们日常生活的各个领域中,嵌入式操作系统的需求也越来越大。嵌入式系统大多工作在对实时性要求很高的环境中,所以,故嵌入式系统往往是实时系统,在实时系统中,任务调度策略是内核设计的关键部分,如何设计任务调度使得各个任务能在其期限内得以完成是实时操作系统设计的一个重要领域。目前在这方面的情况是在理论上研究调度算法的比较多,而把调度算法在实际的实时操作系统中实现的很少。 针对上诉情况,本文试图在该方面作一点尝试,在研究现行的几种调度算法后,将其中的一种算法——改进型的最小裕度调度算法在硬实时操作系统RTLinux上进行了实现。 本文首先着重介绍了现有的一些适用于硬实时系统的调度算法,分析了一些调度算法的优缺点.着重介绍了RTLinux原有的静态优先级调度算法(RM)和最早时限优先调度算法,指出原有算法在一些情况下的不足。然后,着重介绍了实时操作系统RTLinux的实现机制和调度器部分;然后在RTLinux上实现了采用新调度算法的调度器。编写了仿真调度器对新算法与原来的算法进行了仿真比较,提出了一种新的测试实时操作系统调度时间的方法,并对新的调度器进行了测试。更多还原

【Abstract】 With the rapid development of computer technology, communication technology and consumer electronic technology, embedded system has been widely used. There are a lot of demands for embedded operating system in fields of scientific research, engineering design, military technology, entertainment etc. Embedded system works mostly in the hard real-time environment. So embedded system is often real-time system. In real-time system, the task scheduling policy is the key part of kernel design. How to design the scheduling algorithm to make all tasks to meet their deadline is a important problem in the field of real-time operation system, now ,the situation is that many researchs focused on the aspect of theoretical research, but the research about implementation of the theory is less.Based on researching some hard real-time scheduling algorithms, I have implemented the Modified Least Laxity First algorithm on RTLinux. So this paper is about enhancing Real-Time Linux performance by adding to it an Least Laxity First scheduler.Above all, a lot of relevant concepts about real-time some scheduling algorithms are introduced at beginning of this paper. Then analysis and comparison of these scheduling algorithms are discussed. After introducing some relevant concepts, this paper analyses the working principle and typical real-time scheduling algorithm of RTLJnux, and deeply analyses the dynamic MLLF scheduler as well as its detailed implementation.Finally, a new method to test scheduling time and some tests for RTLinux with new scheduler are presented.更多还原