Operating Systems (操作系统原理).ppt

Operating Systems(操作系统原理)n nText book:Text book:uuDinosaur book Dinosaur book（恐龙书）恐龙书）uu操作系统概念操作系统概念 (中译本中译本)n nTeacher:Teacher:uu郑扣根（郑扣根（ZhengZheng KougenKougen）uuProf.Dr.Mr.Prof.Dr.Mn nTATA“OS Homework”“OS Homework”Operating Systems(操作系统原理)n nRefs:Refs:uuKernighan and Pike,The UNIX Programming Kernighan and Pike,The UNIX Programming Environment,Prentice-Hall,1984.Environment,Prentice-Hall,1984.uuW.R.Stevens,Advanced Programming in the UNIX W.R.Stevens,Advanced Programming in the UNIX Environment,Prentice-Hall,1992Environment,Prentice-Hall,1992uuW.R.Stevens,UNIX Network Programming I,W.R.Stevens,UNIX Network Programming I,Prentice-Hall,1997.Prentice-Hall,1997.uuW.R.Stevens,UNIX Network Programming II,W.R.Stevens,UNIX Network Programming II,Prentice-Hall,1998.Prentice-Hall,1998.uuwww.kernel.orgwww.kernel.orgCHAPTER 1:INTRODUCTIONn nWhat is an Operating System?What is an Operating System?n nMainframe SystemsMainframe Systemsn nDesktop SystemsDesktop Systemsn nMultiprocessor SystemsMultiprocessor Systemsn nDistributed Systems Distributed Systems n nClustered SystemClustered Systemn nReal-Time SystemsReal-Time Systemsn nHandheld SystemsHandheld Systemsn nFeature MigrationFeature Migrationn nComputing EnvironmentsComputing EnvironmentsWHAT IS AN OPERATING SYSTEM?An operating system(操作系统)n nmanages the computer resources,such as CPUs,Memories,Hard disks,and acts as an intermediary between the computer hardware and the computer user,n nprovides the system services to user programs,n nprovides an environment for executing programs.What Is an Operating System?The components of a computer systemWhat Is an Operating System?The components of a computer systemn nHardware provides basic computing resources(CPU,Hardware provides basic computing resources(CPU,memory,I/O devices).memory,I/O devices).n nOperating system controls and coordinates the use of Operating system controls and coordinates the use of the hardware among the various application programs the hardware among the various application programs for the various users.for the various users.n nApplications programs define the ways in which the Applications programs define the ways in which the system resources are used to solve the computing system resources are used to solve the computing problems of the users(compilers,database systems,problems of the users(compilers,database systems,video games,business programs).video games,business programs).n nUsers(people,machines,other computers).Users(people,machines,other computers).What Is an Operating System?User viewn nPC usersPC users（PCPC用户）：用户）：The OS is designed to mostly The OS is designed to mostly for ease of use,with some attention paid to for ease of use,with some attention paid to performance,and none paid to resource utilization.performance,and none paid to resource utilization.n nMainframe or minicomputer users(Mainframe or minicomputer users(大型机和小型机用大型机和小型机用户户)：The OS is designed to maximize resource The OS is designed to maximize resource utilization.utilization.n nWorkstation usersWorkstation users（工作站用户）：工作站用户）：The OS is The OS is designed to compromise between resource utilization designed to compromise between resource utilization and individual usability.and individual usability.n nHandheld users Handheld users（手持设备用户）：手持设备用户）：Mostly for Mostly for individual usability,but performance per amount of individual usability,but performance per amount of batter life is important as well.batter life is important as well.What Is an Operating System?System viewn nAn operating system is a resource An operating system is a resource allocatorallocator （分配器）分配器）n nAn operating system is a control program that manages An operating system is a control program that manages the execution of user programs to prevent errors and the execution of user programs to prevent errors and improper use of the computer.improper use of the computer.n nAn operating system is to execute user programs and to An operating system is to execute user programs and to make solving user problems easier.make solving user problems easier.n nWhat is part of the OSWhat is part of the OSuuAn OS is anything a vendor ships.An OS is anything a vendor ships.uuAn OS is the kernel An OS is the kernel（内核）内核）part and all else are part and all else are applications.applications.The matter of what constitutes an OS is becoming The matter of what constitutes an OS is becoming important(Microsoft case in 1998)important(Microsoft case in 1998)What Is an Operating System?System goalsnOS goalsuConvenience:Make the computer convenient to use.uEfficiency:Use the computer hardware in an efficient manner.nBuilding an OS is a complex taskuDesigning and implementationuRevising and updatinguHardware support.nTo find out What the OS is and what it does,let us trace the evolution(not revolution)of OS.MAINFRAME SYSTEMS(大型机系统)n nNo OS No OS（无操作系统）无操作系统）n nBatched OSBatched OS（批处理操作系统批处理操作系统）n nMultiprogrammedMultiprogrammed OS OS（多道程序操作系统）多道程序操作系统）n nTime-sharing OS Time-sharing OS（多时操作系统）多时操作系统）Mainframe Systems:No OSn nDesigner,Implementer,Operator,User Designer,Implementer,Operator,User n nDesigner,Implementer/Operator,User Designer,Implementer/Operator,User n nDrawbacks:Drawbacks:uuScheduling time Scheduling time uuSetup time Setup time uuslowslowMainframe Systems:Batch OSn nThe OS The OS uuwas always resident in memorywas always resident in memoryuuautomatically transferred control from one job to automatically transferred control from one job to another.another.n nBatching:Batching:uuProgrammers submitted jobs in a job control Programmers submitted jobs in a job control languages(shell,languages(shell,awkawk,perlperl)uuOperators batched together jobs with similar needs Operators batched together jobs with similar needs and ran them through the computer as a group.and ran them through the computer as a group.n nDrawbacks:Drawbacks:uufast CPU and slow I/O devices.fast CPU and slow I/O devices.Mainframe Systems:Multiprogrammed OSn nMultiprogrammedMultiprogrammed OS(vs.OS(vs.uniprogrammeduniprogrammed OS)OS)uuKeeping many jobs in memory(see the next slide)Keeping many jobs in memory(see the next slide)uuSwitching to another job if the CPU is idleSwitching to another job if the CPU is idleuuAs long as at least one job needs to execute,the CPU As long as at least one job needs to execute,the CPU is never idle.is never idle.n nMultiprogrammedMultiprogrammed OS OSuuJob scheduling for selecting a job to load into memoryJob scheduling for selecting a job to load into memoryuuCPU scheduling for selecting which job to runCPU scheduling for selecting which job to runuuMemory managementMemory managementuuProtection.Protection.n nDrawback:not interactiveDrawback:not interactiveMainframe Systems:Multiprogrammed OSMainframe Systems:Time-sharing OSn nMemory sharing Memory sharing multiprogrammingmultiprogrammingn nMemory sharing+time sharing Memory sharing+time sharing multiprogramming+multiprogramming+interaction(or multi-tasking)interaction(or multi-tasking)n nThe CPU is The CPU is rapidlyrapidly multiplexed among several jobs that multiplexed among several jobs that are kept in memory.(I/O operation is terribly slow!)are kept in memory.(I/O operation is terribly slow!)n nTime-sharing OSTime-sharing OSuuMemory management(virtual memory)and protectionMemory management(virtual memory)and protectionuuFile system,disk managementFile system,disk managementuuProcess synchronization(Process synchronization(同步同步)and communication)and communicationuuDeadlock handling Deadlock handling（死锁处理）死锁处理）.DESKTOP SYSTEMSn nPersonal computers Personal computers uucomputer system dedicated to a single puter system dedicated to a single user.uuI/O devices keyboards,mice,display screens,small I/O devices keyboards,mice,display screens,small printers.printers.uuIndividuals have sole use of computer and do not need Individuals have sole use of computer and do not need advanced CPU utilization of protection features.advanced CPU utilization of protection features.n nUser convenience and responsiveness not maximizing User convenience and responsiveness not maximizing CPU and peripheral utilizationCPU and peripheral utilizationn nCan adopt some of the technology developed for larger Can adopt some of the technology developed for larger operating system.operating system.uuNot much of utilizationNot much of utilizationuuProtection,and so onProtection,and so onn nMany possible Many possible OSesOSes:(Windows,:(Windows,MacOSMacOS,UNIX,Linux),UNIX,Linux)PARALLEL AND DISTRIBUTED SYSTEMSn nTwo typesTwo typesuuTightly coupled systems Tightly coupled systems（紧耦合系统紧耦合系统）t tParallel systems or multiprocessor systemsParallel systems or multiprocessor systemst tProcessors share memory and a clock;Processors share memory and a clock;communication usually takes place through the communication usually takes place through the shared memory.shared memory.uuLoosed coupled systemsLoosed coupled systems（松耦合系统松耦合系统）t tDistributed systems and clustered systemsDistributed systems and clustered systemst tEach processor has its own local memory;Each processor has its own local memory;processors communicate with one another processors communicate with one another through various communications lines,such as through various communications lines,such as high-speed buses or telephone lines.high-speed buses or telephone lines.Parallel and distributed systems:Parallel systemsn nAdvantages of parallel systems:Advantages of parallel systems:uuIncreased Increased throughputthroughputuuEconomy of scaleEconomy of scale uuIncreased reliabilityIncreased reliabilityt tgraceful degradation(The ability to continue graceful degradation(The ability to continue providing service proportional to the level of providing service proportional to the level of surviving hardware).fail-soft systems(systems surviving hardware).fail-soft systems(systems designed for graceful designed for graceful degrationdegration)n nAsymmetric multiprocessing Asymmetric multiprocessing（非对称处理）非对称处理）uuMaster processor schedules and allocated work to Master processor schedules and allocated work to slave processors.slave processors.uuEach processor is assigned a specific task;Each processor is assigned a specific task;uuMore common in extremely large systemsMore common in extremely large systemsParallel and distributed systems:Parallel systemsn nSymmetric multiprocessing(SMP)Symmetric multiprocessing(SMP)（对称处理）对称处理）uuEach processor runs an identical copy of the Each processor runs an identical copy of the operating system.operating system.uuMany processes can run at once without Many processes can run at once without performance deterioration.performance deterioration.uuMost modern operating systems support SMPMost modern operating systems support SMPn nSMP and ASMP may be the result of either hardware SMP and ASMP may be the result of either hardware and softwareand softwareParallel and distributed systems:Distributed systemsn nAdvantages of distributed systems.Advantages of distributed systems.uuResources Sharing Resources Sharing uuComputation speed up load sharing Computation speed up load sharing uuReliabilityReliabilityuuCommunicationsCommunicationsn nRequires networking infrastructure.Requires networking infrastructure.n nLocal area networks(LAN)or Wide area networks Local area networks(LAN)or Wide area networks(WAN)(WAN)n nMay be either client-server or peer-to-peer systems.May be either client-server or peer-to-peer systems.Parallel and distributed systems:Distributed systemsParallel and distributed systems:Clustered systems（集群系统）n nClustering allows two or more systems to share storage.Clustering allows two or more systems to share storage.n nProvides high reliability.Provides high reliability.n nAsymmetric clusteringAsymmetric clustering:one server runs the application:one server runs the application while other servers standby.while other servers standby.n nSymmetric clusteringSymmetric clustering:all:all N N hosts are running the hosts are running the application.application.REAL-TIME SYSTEMSn nOften used as a control device in a dedicated Often used as a control device in a dedicated application such as controlling scientific experiments,application such as controlling scientific experiments,medical imaging systems,industrial control systems,medical imaging systems,industrial control systems,and some display systems.and some display systems.n nWell-defined fixed-time constraints.Well-defined fixed-time constraints.n nReal-Time systems may be either Real-Time systems may be either hard hard or or softsoft real-time.real-time.Real-Time SystemsHard real-time:Hard real-time:uuSecondary storage limited or absent,data stored in Secondary storage limited or absent,data stored in short term memory,or read-only memory(ROM)short term memory,or read-only memory(ROM)uuConflicts with time-sharing systems,not supported Conflicts with time-sharing systems,not supported by general-purpose operating systems.by general-purpose operating systems.n nSoft real-timeSoft real-timeuuLimited utility in industrial control of roboticsLimited utility in industrial control of roboticsuuUseful in applications(multimedia,virtual reality)Useful in applications(multimedia,virtual reality)requiring advanced operating-system features.requiring advanced operating-system features.HANDHELD SYSTEMSn nPersonal Digital Assistants(Personal Digital Assistants(PDAsPDAs)()(个人数字助理个人数字助理)n nCellular telephonesCellular telephones（手机手机),Pocket PC,),Pocket PC,n nIssues:Issues:uuLimited memoryLimited memoryuuSlow processorsSlow processorsuuSmall display screens.Small display screens.OS FEATURE MIGRATIONCOMPUTING ENVIRONMENTSn nTraditional computingn nWeb-Based Computingn nEmbedded Computing