重庆市中小学班主任基本功大赛决赛(I)

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1、ProcessesandSchedulingSectionIIIObjectiveofschedulingFairness----PreventstarvationEfficiencyThroughputResponsetimeTypesofscheduling（调度类型p379）SortedbyOStypes（按系统类型分类）Batchscheduling（批处理调度）Time-sharingscheduling(分时调度）Real-timescheduling（实时调度）Multiprocessorscheduling（多处理机调度）Sortedbyperformfrequenc

2、yandschedulingunit（按执行频率分类）Long-termscheduling（长程调度）Medium-termscheduling（中程调度）Short-termscheduling（短程调度）I/OschedulingSchedulingandProcessStateTransitions(p380)LevelsofScheduling（分级调度图P381）P382Long-termscheduling(P380)Determines(确定)whichprogramareadmittedtothesystemforprocessing.Controlsthedegree

3、ofmultiprogramming（多道程度）.Onceadmitted（提交）,ajobbecomesaprocessandisaddedtothequeueforshort-termschedulerorformedium-termscheduler.Inabatchsystem,thelong-termschedulerchoosesthejobsheldin(保持在)diskqueueandcreatesprocessesfromthequeuewhenitcan.Twoproblemsforlong-termscheduling（p381）Decidethenumberofp

4、rocessesthatOScantakeon,whichisdecidedbythedegreeofmultiprogramming.Whichjoborjobstoacceptandturninto(转化为)processes.Decidedbyschedulingalgorithm，e.g.FCFS、SJF、HRRNetc…Whentoinvokethelong-termscheduler?StatesofJob:admit,execution,finishMedium-termscheduling（p383）Partoftheswappingfunction(交换功能).Choo

5、seprocessesindisktoswapinforexecution.Short-termscheduling（p383）Knownasthedispatcher（分派器）,executesmostfrequentlyandmakesthefine-grained(细粒度)decisionofwhichprocesstoexecutenext.Theeventtoinvoked（引起）theshort-termschedulingClockinterruptsI/OinterruptsOperatingsystemcallsSignals（信号）SchedulingCriteria

6、（准则）T9.2(p385)UserOriented,PerformanceRelated（面向用户，考虑性能）Responsetime（响应时间）.Fromthesubmission（提交）ofarequestuntiltheresponsebeginstobereceived.Oftenbeusedintime-sharedtime.Turnaround（周转）time.Theinterval（间隙）oftimebetweenthesubmissionofaprocessanditscompletion.Oftenbeusedinbatchsystems.Deadlines（截止期）

7、.Thedeadlinesbespecifiedforaprocess,suchasstartingdeadlinesandcompletiondeadlines.SchedulingCriteria（II）SystemOriented（面向系统）Throughput（吞吐量）.Thenumberofprocessescompletedperunitoftime.Oftenusedinbatchsystem.ProcessorUti