计算机操作系统OperatingSystemOverview

1、计算机操作系统OperatingSystemOverview计算机操作系统-Operating-System-OverviewFigure 2.1 Layers and Views of a Computer SystemComputer HardwareOperating SystemUtilities (Compiler, Database)Applications ProgramsOperatingSystem DesignerProgrammersEnd UserInterrupt processingDevice DriversJob SequencingControl Langua

2、ge InterpreterUser Program AreamonitorMemory layout for a resident(驻留) monitorRead one record0.0015 secondsExecute 100 instructions0.0001 secondsWrite one record0.0015 secondsTOTAL0.0031 secondsFigure 2.4 System Utilization Exlev 256k available memoryJOB1JOB2JOB3Type of JOBHeavy ComputerHeavy I/OHea

3、vy I/ODuration5min15min10minMemory required50k100k80kNeed diskNoNoYesNeed terminalNoYesNoNeed printerNoNoYesTable 2.1 Sle Program Execution Attributes v Single Processor use5/(5+15+10)=17% Memory use=(50*5+100*15+80*10)/256/30 =33% Disk use=10/30=33% Printer use10/30=33% Total time 5+15+1030 Through

4、put 6 job/hour Mean response time（5+20+30）/3=18 Processor use5/15=33% Memory use=(50+100+80)*5+(100+80)*5+100*5/256/15 =65% Disk use=10/15=67% Printer use10/15=67% Total time15 Throughout 12job/hour Mean response time（5+10+15）/3=10Batch Multiprogramming Time Sharing Reducing the spending for accessi

5、ng disk Fig 2.10 Two Views of a Storage SystemVirtual ProcessorReal ProcessorMapper (AddressTranslate)Main MemoryAuxiliaryMemoryVirtualMemoryFiles(a) Users View(b) Operating System Designers ViewVirtualAddressMemoryAddressSwappingRead, WriteCopyLong-term StoreFig 2.11 Key elements of an Operating System for MultiprogrammingService CallHand