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北京航空航天大学硕士学位论文嵌入式Linux系统实时性的研究和改进方案与实现摘要嵌入式技术正在各行各业中得到迅速而广泛的应用，作为其软件核心的嵌入式操作系统更是信息产业界研究的热点。本论文主要围绕如何将Linux操作系统经过改造来提高系统实时性能这一课题进行了探讨和研究。文章首先对嵌入式系统、嵌入式Linux操作系统和实时操作系统进行了简要的介绍，说明了嵌入式实时技术的国内外研发现状。在综合比较现有各种嵌入式操作系统的基础上，分析了使用Linux构造嵌入式实时操作系统的优点和缺陷，并针对这种优缺点，设计了Linux内核的实时改造方案。昀终确定以双内核机制为基础，增加实时硬件抽象层（RTHAL）以简化对原内核的改动的技术实现路线。在分析Linux系统进程调度算法的基础上，提出了一种改进后的调度算法，从而使实时性能进一步得到提高。文章的昀后对新Linux系统的主要实时性能进行了相关测试，通过与原Linux系统做比较，证明本文论述的实现方案是成功的，此外，还展望了嵌入式实时Linux操作系统的发展前景和道路。关键词：嵌入式Linux，实时，调度，双内核机制，实时硬件抽象层I摘要AbstractEmbeddedtechnologyhasbeenappliedinvariousindustries.Asthekernelofitssoftware,theembeddedoperatingsystemisthehotspotoftheresearchininformationindustry.ThisthesisisbasedonthestudyofhowtorebuildLinuxintoahighrealtimeoperatingsystem.Firstly,thepaperintroducesembeddedsystem,embeddedLinuxoperatingsystemandrealtimeoperatingsystem.Itintroducestheresearchactualityofembeddedtechnology.OnthebasisofsyntheticcomparingmanifoldEmbeddedOperatingSystemexitingtoday,thethesisanalyzesexcellencesandlimitationsofusingLinuxconstructingEmbeddedSystem.Furthermore,itdesignsReal-timereconstructionprojectofLinuxkernelcontraposingtheseexcellencesandlimitations.Finally,thetechnologystrategythroughtwo-kernelmechanismissetup,addedRTHALforreducingthemodificationoftheoriginalkernel.ItalsoadvancesanimprovedschedulingarithmeticandimprovestheReal-timeperformancebasedonthestudyofLinux'sschedulingarithmetic.Intheend,thepaperdiscussestheprimaryrealtimeperformancevalueofnewLinux,provingthesuccessoftheschemedescribedinthepaperbycomparisonwiththeoriginalLinuxsystem.Moreover,thepapergivessomeforesightabouttheembeddedrealtimeLinux.Keywords：embeddedLinux,Real-time,scheduling,twokernelmechanism,realtimehardwareabstractlayerII北京航空航天大学硕士学位论文目录第一章绪论...........................................................................................................11.1嵌入式系统............................................................................................................................11.2嵌入式LINUX操作系统.......................................................................................................31.3课题研究背景和目的............................................................................................................61.4论文组织结构........................................................................................................................8第二章嵌入式LINUX实时操作系统................................................................92.1实时操作系统........................................................................................................................92.1.1实时操作系统的概念........................................................................................................92.1.2实时操作系统的发展........................................................................................................92.1.3实时操作系统和通用操作系统的差异..........................................................................102.1.4实时操作系统的性能指标..............................................................................................122.2标准LINUX的实时性能分析.............................................................................................122.2.1Linux本身支持实时性的分析.........................................................................................132.2.2Linux支持硬实时性的技术障碍.....................................................................................132.2.3Linux新内核在嵌入式和实时性方面的增强.................................................................152.3LINUX支持实时性的基本策略...........................................................................................162.3.1直接修改内核使其成为实时内核..................................................................................162.3.2采用双内核机制..............................................................................................................172.3.3兼容内核以及源内核的方法..........................................................................................182.3.4对目前嵌入式实时Linux系统的分析...........................................................................18第三章嵌入式LINUX实时性的解决方案......................................................213.1实时性方案的提出和比较..................................................................................................213.2双内核机制的分析..............................................................................................................223.2.1双内核的基本结构..........................................................................................................223.2.2双内核结构的通信机制..................................................................................................243.3实时硬件抽象层（RTHAL）............................................................................................253.3.1RTHAL的基本结构.........................................................................................................253.3.2RTHAL的作用.................................................................................................................273.3.3对原Linux内核的修改...................................................................................................293.4细粒度时钟的实现.