操作系统概念(英文)(4)
操作系统概念(英文)
October 2012 Operating System Concepts- Chapter4 Threads 10
a traditional process as a single-thread
more than one thread in one process
Fig.4.1 Single and Multithreaded Processes
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resource shared by all threads in the process
Traditional process, also named heavyweight process, has a single thread of control A thread is also called a lightweight process (LWP)
October 2012 Operating System Concepts- Chapter4 Threads 9
Basic concepts (cont.)
线程内容 tID 程序计数器 堆栈 寄存器组 状态 子线程
进程内容 PID 地址空间 全局变量 打开文件 子进程 定时器 信号 信号量 记账信息
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Operating System Concepts- Chapter4 Threads -
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4.1 Overview
4.1.1Why thread needed As described in Chapter 3, the process is as the unit of resource allocation unit of CPU scheduling The costs of process management, such as costs of process creation, cancellation, process switch and process communication, are somewhat high, refer to Fig.3.4, and the concurrency (or multiprogramming degree) may be limited. To reduce costs of process management and improve degrees of concurrency and parallelism, the thread is presented
“操作系统”英语怎么说
“操作系统”英语怎么说名词解释：操作系统(Operating System，简称OS)是管理和控制计算机硬件与软件资源的计算机程序，是直接运行在“裸机”上的最基本的系统软件，任何其他软件都必须在操作系统的支持下才能运行。
你知道怎么用英语表达吗?Microsoft has decided to continue providing virus warnings for the ageing Windows XPoperating system until 2015.The warnings were due to end on 8 April 2014 when all other support for the software is scheduled to stop.However, the numbers still running the 12-year-old operating system convinced it to provide more help.About 30% of all desktop computers are still running XP, according to figures from a research firm.微软已经决定将继续为老一代操作系统Windows XP提供病毒警报直至2015年。
按原来的计划，Windows XP的安全警报以及其他支持服务会在2014年4月8日到期结束。
虽然XP已是12岁“高龄”，但是运行XP的电脑数量之多，证明仍有必要为其提供一些服务。
根据一家研究公司的数字，仍有约30%的台式电脑还在使用运行Windows XP操作系统。
【讲解】文中的operating system就是“操作系统”的意思，可以简写为OS。
其中operating是一个形容词，在这里解释为“操作的”，它还可以解释作“手术的”，如operating room或operating theatre(手术室)、operating table(手术台)。
操作系统概念OperatingSystemconcepts
操作系统概念OperatingSystemconceptsOS⼤题预测进程同步与信号量，对semaphore的定义，wait()和singal()操作进程调度策略，画Gantt图，求各个进程的轮转时间，等待时间，以及平均轮转时间，平均等待时间给出页⾯的引⽤串，根据不同的调度策略（LRU,Opt,FIFO,Clock）进⾏计算，得出缺页次数与缺页率死锁避免，银⾏家算法，系统安全状态（能否找到⼀个安全序列），对于进程的资源请求判断是否会造成死锁（避免算法）给定⽂件的索引结构，计算查找特定记录所需要的磁盘I/O次数，以及⽂件可存储的最⼤⼤⼩操作系统类型简单批处理系统多道程序批处理系统：⽆论何时都有程序在运⾏，从⽽使CPU的利⽤率达到最⼤。
分时系统(time-sharing)：在进程之间频繁切换CPU，以便⽤户在程序运⾏时能与其进⾏交互，特点是⽴即响应。
并⾏/多处理器系统：增加吞吐量（多个处理器加速⽐⼩于N），规模经济（资源共享减少开销），增加可靠性（⼀个处理器故障不会导致系统罢⼯）实时系统分布式系统：资源共享，计算加速，可靠性，通信系统调⽤System CallSystem call - the method used by a process to request action by the operating system.Usually takes the form of a trap (software interrupt).Control passes through an interrupt vector to a service routine in the OS, and the mode bit is automatically set to supervisor mode.The OS verifies that the parameters are correct and legal, executes the request, and returns control to the instruction following the system call.参数传递机制Passing parameters to the kernel for a system call must be performed differently than when using an ordinary functional call. This is because a system call is performed by the kernel itself, which typically runs in a completely different address space than the process which made the call. Thus it is not possible to simply place system call parameters onto the process’ stack as this will not be readily available to the kernel. There are three main methods to pass the parameters required for a system call:(1) Pass the parameters in registers (this may prove insufficient when there are more parameters than registers).(2) Store the parameters in a block, or table, in memory, and pass the address of block as a parameter in a register. This approach is used by Linux and Solaris.(3) Push the parameters onto a stack(内核栈); to be popped off by the OS. Block and stack methods do not limitt the number or length of parameters passed.中断InterruptThe occurrence of an event is usually signaled by a (an) interrupt from either the hardware or the software.Hardware may trigger it at any time by sending a signal to the CPU, usually by way of the system bus.硬件中断，⼜称外部中断，由CPU的外部硬件信号引发。
操作系统概念(英文)
December 2010
Operating System Concepts - Chapter9 Virtual Memory -
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Solution (cont.)
(2) 若再增加300K内存，系统可容纳４个进程同时并发执 行 4 此时，CPU的利用率为 (1— (80%) ) = (1— 0.4096) = 0.5904 所以，若再增加300K内存，cpu利用率可提高： (0.5904—0.488) / 0.488 = 20.98%
Operating System Concepts - Chapter9 Virtual Memory 1
December 2010
Solution
(1) 当系统内存为900K时, 系统可容纳3个进程同时并发执 行 根据题意，进程在执行过程中有80%的I/O等待时间, 表明进程等待I/O的时间占其生命周期时长的80%, 进 程处于waiting状态的概率为0.8 对系统内并发执行的n个进程, 当这n个进程同时处于 I/O等待时, cpu是空闲的 系统内3个并发进程同时处于I/O等待态而导致CPU空闲 的概率为(80%)3=0.512 因此，系统有51.2%的CPU时间被浪费掉了，系统CPU 的利用率为(1—51.2%)＝48.8%。
Operating System Concepts - Chapter9 Virtual Memory 4
December 2010
December 2010
Operating System Concepts - Chapter9 Virtual Memory -
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Solution (cont.)
(3)根据题意，设系统内每个进程在其生命周期内处于 running态执行程序指令的总时间均为T 当系统内存为900K时, 系统可容纳3个进程并发执行。如 果3个进程全部执行完所需时间为L3，则： CPU的利用率=3T / L3=48.8%, L3 = 3T / (48.8%), , 系统吞吐量Th3=3/ L3= (48.8%) / T 当系统内存由900K增至1200K时，系统可容纳４个进程 同时并发执行。设4个进程全部执行完所需时间为L4，则: CPU的利用率 = 4T / L4=59.04%, L4=4T / (59.04%), 系统吞吐量Th4=4/ L4= (59.04%) / T 因此，若再增加300K内存，系统吞吐量可提高： ［(59.04%) / T —(48.8%) / T］/ [(48.8%) / T] = (0.5904—0.488) / 0.488 = 20.98% = 20.98%
操作系统概念operatingsystemconceptssixthedition
客户 － 服务器系统的通用结构
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1.6 集群系统（clustered system）
■ 集群系统将多个CPU集中起来完成计算任务 。然而， 集群系统与并行系统不同 ，它是由两个或多个独立的 系统耦合起来的。
■ 通常接受的定义是集群复读机共享存储并通过LAN网络 紧密链接
■ 通常用来提供高可用性（high availabilit y） ■ 非对称集群（asymmetric clustering）： 一 台机器处
■ Operating System － controls and coordinates the use of the hardware among the various application programs for the various users
■ Applications programs – define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs)
■ 软件实时系统（soft real-time system） ■ 关键实时任务的优先级要高于其他任务的优先级 ，且在完成之前能保持其高优先 级 。与硬实时系统一样 ， 需要限制操作系统内核的延迟：实时任务不能无休止地 等待内核来执行它。 ■ 可以与分时系统集成在一起 ■ 在那些需要快速响应时间的应用程序（如多媒体、虚拟现实） 中是非常有用的。
■ 操作系统的两大目标：
■ 执行用户程序 ， 并且更易于解决用户问题； ■ 更便于使用计算机系统；
操作系统概念(英文)——Syllabus for Operating Systems
Beijing University of Posts and Telecommunications (BUPT)School of Computer Science and TechnologySyllabus for Operating Systems1. OverviewsCourse No.: 313.04103 Course Title: Operating Systems Course Credit: 4 Credits, required courseSemester and Year: Fall 2008 Class: 06406—06410 Teaching hours:z Class teaching: 64 hoursz After-class experiments: 17 hoursz Course design, or professional practice for this course:（操作系统综合课程设计）, 30 hours, 1 credits, conducted inthe 3rd semester.Prerequisites:z Data Structurez Computer Organization Principles2. Lecture MeetingsTime: Monday AM: 10:00 – 12:00Wensday AM: 10:00 – 12:00Location: Room 402, 4th Teaching Building3. FacultyInstructorz Name: Dr. Wen YE (叶文)z Office: Room 918, 3rd Teaching Buildingz Office Hours: Wednesday 3:00 to 4:30 PM,I am also available by appointment at a time more convenientfor you, especially at the end of this semesterz Phone: 86-10-62282633 (O)z E-mail: gryew@, yewen@Graduate Teaching Assistant:z Name: Cheng Yan （成艳），chengy352@Ma Haiying（马海印），mahaiyinmhy@ z Responsibility: checking homework, directing experimentsz Office: Room 918, 3rd Teaching Buildingz Office Hours: Wednesday 3:00 to 4:30 PM, or by appointment 4. Text Book1. Abraham Silberschatz, Peter Baer Galvin, Greg Gagne, Operating System Concepts(Seventh Edition), Higher Education Press and McGraw-Hill Companies, Beijing, May, 2007.References1.Andrew S.Tanenbaum, Modern Operating Systems, ChinaMachine Press and Prentice Hall, Beijing, Jan.1999.2.孙钟秀，费翔林，洛斌，谢立，操作系统教程（第3版），高等教育出版社，北京，2003年8月3.曹聪, 范廉明，操作系统原理与分析，科学出版社，北京，2003年9月。
操作系统概念(英文)
Process Concept (cont.)
3.1.5 Process vs program dynamic vs static process: lifecycle being created —— executing —— being deleted composition： program + data + PCB A program may correspond to several processes; a process may also contains several programs (e.g. main routines, subroutines and procedures )
The process is characterized with dynamic and concurrent features Roles of processes unit of running entity in system, i.e., CPU allocation unit of resource (e.g. memory, files, devices,…) allocation
3.1.2 Process Definition A process is a program in execution the unit of resources (CPU, memory, I/O devices) allocation runs concurrently with other processes
October 2012
Operating System Concepts- Chapter3 Processes -
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§3.2 Process Scheduling
操作系统概念(英文)
September 2012
§1.2 Computer-System Organization
1.2.1 Computer-System Operation Fig. 1.2 A modern computer system
Commonly acknowledged classifications of OS PC/Desktop OS : Windows, Linux，Mac OS X Server OS : Unix, Linux, Windows NT Mainframe OS : Unix, Linux——open source！！ Embedded OS : Vxworks, (Palm OS), (Symbian), (WinCE)/Windows Mobile/Phone, Android, iOS, embedded Linux (e.g. μcLinux)
September 2012 Operating System Concepts- Chapter1 Introduction 8
1.1.2 OS Concepts (cont.)
For OS definitions in other textbooks, refer to Appendix 1.B OS definitions
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Operating System Concepts- Chapter1 Introduction -
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Fig.1.1-1 Components of a computer system
Application Software