技术根儿扎得深，不怕“首都”狂风吹！

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请求，为用户分配i/o设备，管理i/o的缓存 和驱动i/o设备等功能。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"文件管理","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"计算机系统把大量需要长时间保留的数据信息已文件的形式存放在外存设备中，操作系统需要根据自己的文件管理程序完成外存空间的分配，回收，文件的按名存取，文件的组织，共享与保护。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"3.成长历程","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/3b/3b5d8f414f74a951200d621680f994f4.png","alt":null,"title":"","style":[{"key":"width","value":"100%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"3.1.无操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"硬件环境：电子管，没有用来存储程序的内存。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"使用方式：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1.操作人员把作业挂到输入设备上。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2.启动设备。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"3.运算结束取出结果。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"例子：操作员用穿孔卡片表示程序和数据，需要运行这些穿孔卡表示作业时，程序要把卡片和交给输入室的计算机输入员，然后程序员等待输出结果。计算机运行当前作业后，将计算机结果打印输出，操作员到打印机上撕下运算结果送到输出室，程序员可以在这里渠道自己的运行输出结果。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"新问题：机器速度很快的时候cpu长时间等待人工操作，造成来cpu资源的浪费。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"3.2.单道批操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"硬件环境：晶体管，开始使用磁性存储设备，内外存容量增加。计算机的运算速度提高。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"解决无操作系统的问题，利用磁性存储设备提高输入/输出速度。同时程序常驻内存并自动装入作业，撤销作业，输出运算结果。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"使用方式： ","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1.使用一台相对偏移的，专门用来输入的计算机把作业从穿孔卡输入到磁带上，一盘磁带可以存储多个作业。 ","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2.操作员把存有批量作业的磁带装入到磁带机。 ","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"3.操作员在专门技术的，性能较高的计算机上装入早期的操作系统，也称为“监控程序”，它能自动从磁带读入作业并运行。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"4.把作业运行结果写入专门存放输出结果的磁带上。 ","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"5.每当一个作业运行结束之后，操作系统自动从磁带中读取下一个作业并使之运行。 ","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"6.当一批作业完成后，操作员取下输入和输出磁带，将输入磁带换成下一批作业。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"特点：内存中只能驻留一道用户作业，cpu 和 内存作业被用户作业独占。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"新问题：在设备控制器控制设备完成输入/输出的一段时间内不需要 cpu 干预，此段时间内 cpu 空闲，无事可做。对于租用计算的用户而言，损失了cpu 的机时，而计算损失了系统的吞吐量。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"3.3.多道批操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"硬件环境：集成电路","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"商业活动中一些商人尝试生产一种通用计算机试图把用于科学计算，工程计算及磁带归档，打印处理的两类计算机合二为一。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通用计算机的新问题","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1.cpu 密集型的工作 ，输入输出设备操作较少。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"2.输入/输出 密集型的工作 ，cpu 等待最多产生 80%～90%浪费。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"最开始的想法：将内存分成几个部分，每一部分存放不同的作业，当一个作业等待输入/输出操作完成时候，另位一个作业可以使用cpu，任何时刻，当一个作业运行完毕，操作系统会自动从外存装入另一个作业到空闲的内存区域。这就是产生了多道批操作系统。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"新问题：早期的多到批操作系统不具备交互功能，提交作业之后，等待很长时间可能获取的只是一个语法的error。后面就产生了分时操作系统。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"3.4.微机器操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"个人计算机","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"3.5.实时操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"支持实时计算的系统，要求规定时间内计算出 1 + 1 = 2。不仅是计算出 1 +1 =2；","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"3.6.反思与对比","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"单道批操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"自动性：自动将作业装入内存内存运行，当运行完成后自动撤销运行完毕的作业，并异常装入下一个作业。使之运行。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"顺序性： 按照顺序依次将作业装入内存，先装入内存的作业先运行完毕。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"单道性：任何时刻只有一道作业","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"多道批操作系统","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"多道性：在内存中可以同时驻留多道程序，当cpu上对工作执行i/0操作时候，该cpu可以执行其他作业，从而提高系统资源的利用率和吞吐量。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"无序性：多个任务完成的顺序与他们进入内存的顺序之间没有严格的对应关系，同时驻留内存中的作业，其获得cpu的顺序和执行的进度无法预知。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"调度性：多道程序系统必须具备作业的调度功能。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"复杂性：多道程序系统对作业共享资源的管理，作业的并发执行，及分时系统的终端用户管理问题。因此其功能和实现计算比单到批覆杂的多。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"优点与不足：提高 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的软件和数据结构都放置在一个逻辑模块中，对外出的用户程序提供一个完整的内核界面（系统调用）。结构简单，便于理解和实现，而系统所有部分都集中在一个内核中，效率较高。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不足：整个系统由若干具有独立功能的子程序组成，系统部分之间没有明确的位置概念，彼此没有信息隐藏，运行一个子程序调用其他子程序。由于各个子程序之间可以相互调用，系统关系复杂，容易引起循环调用和死锁。修改一个子程序往往导致若干相关部分的变动，系统的可修改性和可维护性较差。","attrs":{}}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"5.3.层次结构模型","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"单结构体之间的各个部分紧密依赖，互相调用，当系统模块较多时候，无序的相互调用\b，造成系统的复杂度难以驾驭。层次结构的基本思想将系统分解为多个小的，容易理解的层，系统功能被隔离在不同的层中，每一层提供对系统功能的部分“抽象”，然后采用单向的调用顺序，形成一串彼此联系的对系统功能的“抽象串”，最终形成对整个功能的抽象。“分层”结构使操作系统中的各个模块之间的组织和依赖关系清晰明了，系统的可读性，可靠性，可移植性得到了增强。此外，对某一层的修改或替换只影响临近两层。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不足：分层设计的困难之处在于如何确定各层的顺序和内容，处理不好将会出现“循环依赖”问题。另外一个就是系统性能问题，有时候系统完成一个功能需要穿越多个层才能实现，系统的颗粒度越小，所花费的时间就越大。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"将所有功能模块放在内核模型中现有不足是功能和代码的增加结构变得复杂\b\b，这种系统的代码变得可扩展性，可移植性，可维护性越来越差。错误也随之增多。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"5.5.客户/服务器模型与微内核","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"微内核用水平分层结构代替了原来的传统的纵向分层的结构，这样带来的好处是系统结构清晰，就有较高的灵活性，可靠性，可维护性；首先只要接口规范，操作系统可以方便的增加和删除服务功能，系统具有很好的灵活性。","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不足：微内核的设计有一个严重的不足就是效率不高；微内核采用消息传递机制来实现组件之间的通信，消息收发的代价比传统的操作系统要大。应为任何消息的传递潜在的地方都有可能跨越系统的边界。那么参数需要被复制而不是从发送者的栈引用。另外，发送者和接收着消息之间的同步也增加了系统的开销。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"改进：一，直接优化系统的消息传递机制。二，扩大微内核并把关键性服务程序和驱动程序加入到内核中从而减少系统在用户态和核心态直接的切换。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"微内核技术是现在操作系统额一个发展趋势，结合面向对象设计的方法，微内核具有更多地应用空间。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"5.6.动态可扩展结构模型","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":" 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