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1、UnixSystemKernelInstructors:Fu-ChiungCheng(鄭福炯)AssociateProfessorComputerScience&EngineeringTatungInstituteofTechnology1Unix:IntroductionOperatingSystem:asystemthatmanagestheresourcesofacomputer.Resources:CPUs,Memory,I/Odevices,NetworkKernel:thememoryresidentportionofUnixsystemFilesys
2、temandprocesscontrolsystemaretwomajorcomponentsofUnixKernel.2ArchitectureofUnixSystemhardwarekernelshwhodateedwcgrepasnroffldcccppemacsOtherappsOSinteractsdirectlywiththehardwareSuchOSiscalledsystemkernel3UnixSystemKernelThreemajortasksofkernel:ProcessManagementDeviceManagementFileMan
3、agementThreeadditionalServicesforKernel:VirtualMemoryNetworkingNetworkFileSystemsExperimentalKernelFeatures:MultiprocessorsupportLightweightprocess(thread)support4BlockDiagramofSystemKernelSystemCallInterfaceFileSubsystemInter-processcommunicationSchedulerMemorymanagementProcesscontro
4、lsubsystemDevicedrivershardwarecontrolhardwareLibrariesUserProgramsUserLevelKernelLevelHardwareLevel5ProcessControlSubsystemProcessSynchronizationInterprocesscommunicationMemorymanagement:Scheduler:processscheduling(allocateCPUtoProcesses)6FilesubsystemAfilesystemisacollectionoffilesa
5、nddirectoriesonadiskortapeinstandardUNIXfilesystemformat.Kernel’sfilesybsystemregulatesdataflowbetweenthekernelandsecondarystoragedevices.7HardwareControlHardwarecontrolisresponsibleforhandlinginterruptsandforcommunicatingwiththemachine.DevicessuchasdisksorterminalsmayinterrupttheCPUw
6、hileaprocessisexecuting.Thekernelmayresumeexecutionoftheinterruptedprocessafterservicingtheinterrupt.8ProcessesAprogramisanexecutablefile.Aprocessisaninstanceoftheprograminexecution.Forexample:createtwoactiveprocesses$emacs&$emacs&$psPIDTTYTIMECMD12893pts/40:00tcsh12581pts/40:01emacs1
7、2582pts/40:01emacs$9ProcessesAprocesshastext:machineinstructions(maybesharedbyotherprocesses)datastackProcessmayexecuteeitherinusermodeandinkernelmode.Processinformationarestoredintwoplaces:ProcesstableUsertable10UsermodeandKernelmodeAtanygiveninstantacomputerrunningtheUnixsystemiseit
8、herex
