中科大操作系统原理与实现课件5_CPU_Scheduling1.pdf
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中科大操作系统原理与实现课件5_CPU_Scheduling1.pdf

中科大操作系统原理与实现课件5_CPU_Scheduling1.pdf

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操作系统原理与设计第5章CPUSchedulingII陈香兰中国科学技术大学计算机学院2009年09月01日......提纲Multiple-ProcessorSchedulingReal-TimeSchedulingOSexamplesAlgorithmEvaluation小结和作业......OutlineMultiple-ProcessorSchedulingReal-TimeSchedulingOSexamplesAlgorithmEvaluation小结和作业......Multiple-ProcessorSchedulingIOnesingleprocessor!multipleCPUSICPUschedulingmorecomplexILoadsharingITobesimple,supposeItheprocessorsareidentical–homogeneous–intermsoftheirfunctionalityIso,anyprocessorcanexecuteanyprocessinthequeue......ApprochestoMultiple-ProcessorSchedulingIAsymmetricmultiprocessing–onlyoneprocessoraccessesthesystemdatastructures,alleviatingtheneedfordatasharingpISymmetricmultiprocessingIonecommonreadyqueue,orIoneprivatereadyqueueforeachprocessor......ProcessorAffinityIMigrationofprocessesfromoneprocessortoanotherprocessorCOSTsmuch.IForexample:cacheImostSMPsystemstrytoavoidsuchmigrationIProcessoraffinity:aprocesshasanaffinityfortheprocessoronwhichitiscurrentlyrunning.ISOFTaffinityVS.HARDaffinity.......LoadBalancingILoadbalanceingattemptstokeeptheworkloadevenlyIforSMPsystemwithoneprivatereadyqueueforeachprocessorItwogeneralapproachesIpushmigrationIpullmigrationoftenworkstogetherinloadbalancingsystemsIloadbalancingVS.processoraffinity......SymmetricMultithreadingIIINTEL:hyperthreadingtechnology(HT)IlogicalprocessorsVS.physicalprocessorsIeachlogicalprocessorhasitsownarchitecturestate,includinggeneral-purposeregistersandmachine-stateregisters,andinterruptsIshare:cachememoryandbuesesI?fromtheviewpointofOS?......OutlineMultiple-ProcessorSchedulingReal-TimeSchedulingOSexamplesAlgorithmEvaluation小结和作业......Real-Time.SchedulingIHardreal-timesystems–requiredtocompleteacriticaltaskwithinaguaranteedamountoftimeISoftreal-timecomputing–requiresthatcriticalprocessesreceivepriorityoverlessfortunateonesIOS1.priorityscheduling2.shortdispatchlatencyIapproachesforshortdispatchlatency1.preemption1.1