Chapter2:

Computer-SystemStructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:

Computer-System1UniprocessorComputer-SystemArchitecturecontrollerUniprocessorComputer-SystemA2ControllerAdevicecontrollerisapartofacomputersystemthatmakessenseofthesignalsgoingto,andcomingfromtheCPUprocessor.Eachdevicecontrollerisinchargeofaparticulardevicetype.Devicecontrollersusebinaryanddigitalcodes.Eachdevicecontrollerhasalocalbufferandacommandregister.I/Oisfromthedevicetolocalbufferofcontroller.I/OdevicesandtheCPUcanexecuteconcurrently.DevicecontrollerscommunicatewiththeCPUbycausinganinterrupt.ControllerAdevicecontroller3FunctionsofdevicecontrollersReceivingandunderstandingthecommandsofCPUimplementingthedataexchangebetweenCPUanddevices(formatconversion)RecordingthestatusofdevicetobequeriedbyCPU(statusregister)IdentifyingtheaddressofeachdeviceFunctionsofdevicecontroller4CommonFunctionsofInterruptsInterruptstransferscontroltotheinterruptserviceroutinegenerally,throughtheinterruptvector,whichcontainstheaddressesofalltheserviceroutines.

通常中斷通過中斷向量把控制傳給中斷服務(wù)程序Interruptarchitecturemustsavetheaddressoftheinterruptedinstruction.Incominginterruptsaredisabledwhileanotherinterruptisbeingprocessedtopreventalostinterrupt.Atrap

isasoftware-generatedinterruptcausedeitherbyanerrororauserrequest.Anoperatingsystemisinterruptdriven.CommonFunctionsofInterrupts5InterruptHandlingTheoperatingsystempreservesthestateoftheCPUbystoringregistersandtheprogramcounter.Determineswhichtypeofinterrupthasoccurred:polling

vectoredinterruptsystemSeparatesegmentsofcodedeterminewhatactionshouldbetakenforeachtypeofinterruptInterruptHandlingTheoperatin6InterruptTimeLineForaSingleProcessDoingOutput(P21)InterruptTimeLineForaSing7Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:Computer-System8I/OStructure1.Nochannel(IOP):pollingCPU-OrientedCPURAMCCCCDiskDrivePrinterDeviceSystemBus…I/OStructure1.Nochannel(IO9I/OStructure2.channel(IOP):Memory-OrientedC1IOP1CPURAMIOP2C2C3C4Device1Device2Device3Device4Device5Device6Device7I/OStructure2.channel(IOP):10HowtooutputthedatainRAM?ConstructachannelprogramSubmitthechannelprogramtothecorrespondingIOPviaRAMTheIOPexecutesthechannelprogramTheIOPnotifiesCPUbycausinganinterruptuponcompletionAchannelprogramisasequenceofI/Oinstructionsexecutedbytheinput/outputchannelprocessor(IOP).Thechannelprogramconsistsofoneormorechannelcommandwords.HowtooutputthedatainRAM11TwoI/OMethodsSynchronousAsynchronousTwoI/OMethodsSynchronousAsyn12SynchronousI/OAfterI/Ostarts,controlreturnstouserprogramonlyuponI/Ocompletion.

waitinstructionidlestheCPUuntilthenextinterruptwaitloop(contentionformemoryaccess).AtmostoneI/Orequestisoutstandingatatime,nosimultaneousI/Oprocessing.SynchronousI/OAfterI/Ostart13AsynchronousI/OAfterI/Ostarts,controlreturnstouserprogram,withoutwaitingforI/Ocompletion.

Systemcall–requesttotheoperatingsystemtoallowusertowaitforI/Ocompletion.Device-statustablecontainsentryforeachI/Odeviceindicatingitstype,address,andstate.OperatingsystemindexesintoI/Odevicetabletodeterminedevicestatusandtomodifytableentrytoincludeinterrupt.ThemainadvantageofasynchronousI/Oisincreasedsystemefficiency.AsynchronousI/OAfterI/Ostar14Device-StatusTableDevice-StatusTable15I/OStructureProgrammedinput/output(PIO)isamethodoftransferringdatabetweentheCPUandaperipheral.Ingeneral,programmedI/OhappenswhensoftwarerunningontheCPUusesinstructionsthataccessI/OaddressspacetoperformdatatransferstoorfromanI/Odevice.WithDirectMemoryAccess(DMA),theCPUwouldinitiatethetransfer,dootheroperationswhilethetransferisinprogress,andreceiveaninterruptfromtheDMAcontrolleroncetheoperationhasbeendone.I/OStructureProgrammedinput/16DirectMemoryAccess(DMA)StructureUsedforhigh-speedI/Odevicesabletotransmitinformationatclosetomemoryspeeds.DevicecontrollertransfersblocksofdatafrombufferstoragedirectlytomainmemorywithoutCPUintervention.Onlyoneinterruptisgeneratedperblock,ratherthantheoneinterruptperbyte.DirectMemoryAccess(DMA)Str17Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructure

StorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:Computer-System18StorageStructureMainmemory

–onlylargestoragemediathattheCPUcanaccessdirectly.Secondarystorage

–extensionofmainmemorythatprovideslargenonvolatile

storagecapacity.Magneticdisks

–rigidmetalorglassplatterscoveredwithmagneticrecordingmaterialDisksurfaceislogicallydividedintotracks,whicharesubdividedintosectors.Thediskcontrollerdeterminesthelogicalinteractionbetweenthedeviceandthecomputer.StorageStructureMainmemory–19Moving-HeadDiskMechanismPositioningtime(random-accesstime)seektimerotationallatencytransfertimeTodecreasemechanicaldelays,i.e.,theseektimeandtherotationallatencyè

DiskSchedulingAlgorithmMoving-HeadDiskMechanismPosi20Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchy

HardwareProtectionGeneralSystemArchitectureChapter2:Computer-System21StorageHierarchyStoragesystemsorganizedinhierarchy.Speed

cost

volatility

Caching

–copyinginformationintofasterstoragesystem;mainmemorycanbeviewedasafastcacheforsecondarystorage.StorageHierarchyStoragesyste22Storage-DeviceHierarchy寄存器緩存主存儲器電子盤磁盤光盤磁帶Storage-DeviceHierarchy寄存器23Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtection

GeneralSystemArchitectureChapter2:Computer-System24HardwareProtectionDual-ModeOperationI/OProtectionMemoryProtectionCPUProtectionHardwareProtectionDual-ModeO25Dual-ModeOperationSharingsystemresourcesrequiresoperatingsystemtoensurethatanincorrectprogramcannotcauseotherprogramstoexecuteincorrectly.Providehardwaresupporttodifferentiatebetweenatleasttwomodesofoperations.

至少在兩個運行模式之間提供硬件支持1. Usermode

–executiondoneonbehalfofauser.2. Monitormode(alsosupervisormodeorsystemmode)–executiondoneonbehalfofoperatingsystem.Dual-ModeOperationSharingsys26userWhenaninterruptorfaultoccurshardwareswitchestomonitormode.Dual-ModeOperation(Cont.)Modebitaddedtocomputerhardware(PSW)toindicatethecurrentmode:monitor(0)oruser(1).Privileged

instructions

canbeissuedonlyinmonitormode.特權(quán)指令只能在管態(tài)下執(zhí)行

monitorInterrupt/faultsetusermodeuserWhenaninterruptorfault27I/OProtectionPrivilegedinstructionsAllI/Oinstructionsareprivilegedinstructions.Enable/disableinterruptsModifyaddressregistersSetPSWMustensurethatauserprogramcouldnevergaincontrolofthecomputerinmonitormode.I/OProtectionPrivilegedinstr28MemoryProtectionMustprovidememoryprotectionatleastfortheinterruptvectorandtheinterruptserviceroutines.Inordertohavememoryprotection,addtworegistersthatdeterminetherangeoflegaladdressesaprogrammayaccess:baseregister

–holdsthesmallestlegalphysicalmemoryaddress.limitregister

–containsthesizeoftherangeMemoryoutsidethedefinedrangeisprotected.MemoryProtectionMustprovide29ABaseAndAlimitRegisterDefineALogicalAddressSpaceABaseAndAlimitRegisterDe30HardwareProtectionWhenexecutinginmonitormode,theoperatingsystemhasunrestrictedaccesstobothmonitoranduser’smemory.Theloadinstructionsforthebaseandlimitregistersareprivilegedinstructions.HardwareProtectionWhenexecut31CPUProtectionTimer

–interruptscomputerafterspecifiedperiodtoensureoperatingsystemmaintainscontrol.Timerisdecrementedeveryclocktick.Whentimerreachesthevalue0,aninterruptoccurs.Timercommonlyusedtoimplementtimesharing.Timeralsousedtocomputethecurrenttime.

Load-timerisaprivilegedinstruction.CPUProtectionTimer–interrup32Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:Computer-System33General-SystemArchitectureGiventheI/Oinstructionsareprivileged,howdoestheuserprogramperformI/O?Systemcall

–themethodusedbyaprocesstorequestactionbytheoperatingsystem.Usuallytakestheformofatraptoaspecificlocationintheinterruptvector.ControlpassesthroughtheinterruptvectortoaserviceroutineintheOS,andthemodebitissettomonitormode.Themonitorverifiesthattheparametersarecorrectandlegal,executestherequest,andreturnscontroltotheinstructionfollowingthesystemcall.General-SystemArchitectureGiv34UseofASystemCalltoPerformI/OUseofASystemCalltoPerfor35HomeworkP41-P42

2.9HomeworkP41-P4236Chapter2:

Computer-SystemStructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:

Computer-System37UniprocessorComputer-SystemArchitecturecontrollerUniprocessorComputer-SystemA38ControllerAdevicecontrollerisapartofacomputersystemthatmakessenseofthesignalsgoingto,andcomingfromtheCPUprocessor.Eachdevicecontrollerisinchargeofaparticulardevicetype.Devicecontrollersusebinaryanddigitalcodes.Eachdevicecontrollerhasalocalbufferandacommandregister.I/Oisfromthedevicetolocalbufferofcontroller.I/OdevicesandtheCPUcanexecuteconcurrently.DevicecontrollerscommunicatewiththeCPUbycausinganinterrupt.ControllerAdevicecontroller39FunctionsofdevicecontrollersReceivingandunderstandingthecommandsofCPUimplementingthedataexchangebetweenCPUanddevices(formatconversion)RecordingthestatusofdevicetobequeriedbyCPU(statusregister)IdentifyingtheaddressofeachdeviceFunctionsofdevicecontroller40CommonFunctionsofInterruptsInterruptstransferscontroltotheinterruptserviceroutinegenerally,throughtheinterruptvector,whichcontainstheaddressesofalltheserviceroutines.

通常中斷通過中斷向量把控制傳給中斷服務(wù)程序Interruptarchitecturemustsavetheaddressoftheinterruptedinstruction.Incominginterruptsaredisabledwhileanotherinterruptisbeingprocessedtopreventalostinterrupt.Atrap

isasoftware-generatedinterruptcausedeitherbyanerrororauserrequest.Anoperatingsystemisinterruptdriven.CommonFunctionsofInterrupts41InterruptHandlingTheoperatingsystempreservesthestateoftheCPUbystoringregistersandtheprogramcounter.Determineswhichtypeofinterrupthasoccurred:polling

vectoredinterruptsystemSeparatesegmentsofcodedeterminewhatactionshouldbetakenforeachtypeofinterruptInterruptHandlingTheoperatin42InterruptTimeLineForaSingleProcessDoingOutput(P21)InterruptTimeLineForaSing43Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:Computer-System44I/OStructure1.Nochannel(IOP):pollingCPU-OrientedCPURAMCCCCDiskDrivePrinterDeviceSystemBus…I/OStructure1.Nochannel(IO45I/OStructure2.channel(IOP):Memory-OrientedC1IOP1CPURAMIOP2C2C3C4Device1Device2Device3Device4Device5Device6Device7I/OStructure2.channel(IOP):46HowtooutputthedatainRAM?ConstructachannelprogramSubmitthechannelprogramtothecorrespondingIOPviaRAMTheIOPexecutesthechannelprogramTheIOPnotifiesCPUbycausinganinterruptuponcompletionAchannelprogramisasequenceofI/Oinstructionsexecutedbytheinput/outputchannelprocessor(IOP).Thechannelprogramconsistsofoneormorechannelcommandwords.HowtooutputthedatainRAM47TwoI/OMethodsSynchronousAsynchronousTwoI/OMethodsSynchronousAsyn48SynchronousI/OAfterI/Ostarts,controlreturnstouserprogramonlyuponI/Ocompletion.

waitinstructionidlestheCPUuntilthenextinterruptwaitloop(contentionformemoryaccess).AtmostoneI/Orequestisoutstandingatatime,nosimultaneousI/Oprocessing.SynchronousI/OAfterI/Ostart49AsynchronousI/OAfterI/Ostarts,controlreturnstouserprogram,withoutwaitingforI/Ocompletion.

Systemcall–requesttotheoperatingsystemtoallowusertowaitforI/Ocompletion.Device-statustablecontainsentryforeachI/Odeviceindicatingitstype,address,andstate.OperatingsystemindexesintoI/Odevicetabletodeterminedevicestatusandtomodifytableentrytoincludeinterrupt.ThemainadvantageofasynchronousI/Oisincreasedsystemefficiency.AsynchronousI/OAfterI/Ostar50Device-StatusTableDevice-StatusTable51I/OStructureProgrammedinput/output(PIO)isamethodoftransferringdatabetweentheCPUandaperipheral.Ingeneral,programmedI/OhappenswhensoftwarerunningontheCPUusesinstructionsthataccessI/OaddressspacetoperformdatatransferstoorfromanI/Odevice.WithDirectMemoryAccess(DMA),theCPUwouldinitiatethetransfer,dootheroperationswhilethetransferisinprogress,andreceiveaninterruptfromtheDMAcontrolleroncetheoperationhasbeendone.I/OStructureProgrammedinput/52DirectMemoryAccess(DMA)StructureUsedforhigh-speedI/Odevicesabletotransmitinformationatclosetomemoryspeeds.DevicecontrollertransfersblocksofdatafrombufferstoragedirectlytomainmemorywithoutCPUintervention.Onlyoneinterruptisgeneratedperblock,ratherthantheoneinterruptperbyte.DirectMemoryAccess(DMA)Str53Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructure

StorageHierarchyHardwareProtectionGeneralSystemArchitectureChapter2:Computer-System54StorageStructureMainmemory

–onlylargestoragemediathattheCPUcanaccessdirectly.Secondarystorage

–extensionofmainmemorythatprovideslargenonvolatile

storagecapacity.Magneticdisks

–rigidmetalorglassplatterscoveredwithmagneticrecordingmaterialDisksurfaceislogicallydividedintotracks,whicharesubdividedintosectors.Thediskcontrollerdeterminesthelogicalinteractionbetweenthedeviceandthecomputer.StorageStructureMainmemory–55Moving-HeadDiskMechanismPositioningtime(random-accesstime)seektimerotationallatencytransfertimeTodecreasemechanicaldelays,i.e.,theseektimeandtherotationallatencyè

DiskSchedulingAlgorithmMoving-HeadDiskMechanismPosi56Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchy

HardwareProtectionGeneralSystemArchitectureChapter2:Computer-System57StorageHierarchyStoragesystemsorganizedinhierarchy.Speed

cost

volatility

Caching

–copyinginformationintofasterstoragesystem;mainmemorycanbeviewedasafastcacheforsecondarystorage.StorageHierarchyStoragesyste58Storage-DeviceHierarchy寄存器緩存主存儲器電子盤磁盤光盤磁帶Storage-DeviceHierarchy寄存器59Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtection

GeneralSystemArchitectureChapter2:Computer-System60HardwareProtectionDual-ModeOperationI/OProtectionMemoryProtectionCPUProtectionHardwareProtectionDual-ModeO61Dual-ModeOperationSharingsystemresourcesrequiresoperatingsystemtoensurethatanincorrectprogramcannotcauseotherprogramstoexecuteincorrectly.Providehardwaresupporttodifferentiatebetweenatleasttwomodesofoperations.

至少在兩個運行模式之間提供硬件支持1. Usermode

–executiondoneonbehalfofauser.2. Monitormode(alsosupervisormodeorsystemmode)–executiondoneonbehalfofoperatingsystem.Dual-ModeOperationSharingsys62userWhenaninterruptorfaultoccurshardwareswitchestomonitormode.Dual-ModeOperation(Cont.)Modebitaddedtocomputerhardware(PSW)toindicatethecurrentmode:monitor(0)oruser(1).Privileged

instructions

canbeissuedonlyinmonitormode.特權(quán)指令只能在管態(tài)下執(zhí)行

monitorInterrupt/faultsetusermodeuserWhenaninterruptorfault63I/OProtectionPrivilegedinstructionsAllI/Oinstructionsareprivilegedinstructions.Enable/disableinterruptsModifyaddressregistersSetPSWMustensurethatauserprogramcouldnevergaincontrolofthecomputerinmonitormode.I/OProtectionPrivilegedinstr64MemoryProtectionMustprovidememoryprotectionatleastfortheinterruptvectorandtheinterruptser