导　　师： 刘卫国;张衡

学科专业： H1204

授予学位： 硕士

作　　者： ;

机构地区： 中南大学

摘　　要： linux以其开放源码、功能强大、模块化设计、支持多种硬件平台、函数接口符合国际和工业标准等优点，被广泛的应用于构造嵌入式实时操作系统。但由于linux是一个通用操作系统，实时性能方面的不足严重的限制了它在嵌入式领域的发展。linux2.4内核以其小巧精悍、稳定可靠的特点占据着很大一部分嵌入式linux市场，因此改进linux2.4内核的可抢占性来提高它的实时性能是非常重要的。 本文以linux2.4.36内核源码为基础，分析lanux内核的原理结构，详细分析影响linux内核实时性能的因素，提出了一个改进linux内核实时性的方案，该方案的主要思路是修改标准linux内核，使其具有内核抢占能力，这样系统即使处于内核态时也可以进行进程调度，从而尽快对更高优先级进程做出响应。为了避免内核抢占带来的同步问题，该方案还实现了内核抢占禁区来保护系统能够安全的进行内核抢占，主要办法是修改自旋锁、中断处理模块、调度模块等内核机制。 本文还设计并实现了一测试linux系统实时性能的方案，并使用该测试方案测试了标准内核和抢占内核的系统延迟时间，测试结果表明修改后的内核实时性能得到了有效改善。 最后，本文对改造linux实时内核的方案进行了总结，并指出了进一步的研究工作，如细化临界区和在多cpu系统上进行实验测试等。 Linux is widely used in constructing real-time operating system because of the advantages of open-source code,powerful function,modular design,support multi-hardware platforms,function interface with international industry standards. However, because Linux is an all-purpose operation system,lack of real-time ability,which serious limits its development in the embedded field. Linux 2.4 kernel occupies a large part of embedded Linux market because of its smart,stable and reliable characteristics. Therefore,improving the preempt-ability of Linux 2.4 kernel to enhance real time ability is important. Based on Linux 2.4.36 kernel source codes,this thesis analyses the principle structure and the factors that impact Linux real-time performance, then proposed a solution for improving real-time ability, the main idea of the solution is through modifying standard Linux kernel to make it to have kernel-preempt capability, then system can scheduling process even in the kernel state, consequently response to higher priority process as soon as possible. In order to avoid synchronization problems that bring by kernel-preempt, this solution designed kernel-preempt forbid section to protect system to be preempted safety in kernel state, the main approach is to modify spin lock,interrupt processing module,Scheduling module and other kernel mechanism. This thesis also designs and realizes a solution for testing the real-time ability of Linux system, and used it to test the latency of the standard kernel and preempt kernel. Test results show that the real-time ability is improved after modifies. Finally,this thesis summarizes the solution for improving real-time kernel and point out the further tasks of our study,such as detailing the critical section and testing in CPU system.

关 键 词： 嵌入式操作系统 实时性能

分 类 号： [TP316.9]

领　　域： [自动化与计算机技术] [自动化与计算机技术]