计算机操作系统期末考试题集锦Word格式.doc

计算机操作系统期末考试题集锦Word格式.doc

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5、Theoperatingsystemisresponsibleforthefollowingactivitiesinconnectionwithfilemanagement:

（Creatinganddeletingfiles）,Creatinganddeletingdirectoriestoorganizefiles,Supportingprimitivesformanipulatingfilesanddirectories,Mappingfilesonto（secondarystorage）,Backingupfilesonstable（nonvolatile）storagemedia.

6、Fiveservicesprovidedbyanoperatingsystemthataredesignedtomakeitmoreconvenientforuserstousethecomputersystemare（Program）,I/Ooperations,File-systemmanipulation,（Communications）andErrordetection.

7、Thetwomodelsofinterprocesscommunicationaremessage－passingmodelandthe（share-memoryFF）model.

8、Systemcallsallow（running）processestorequestservicesoftheoperatingsystem.

9、Thethreemajoractivitiesofanoperatingsysteminregardtosecondary-storagemanagementareFree-spacemanagement,Storageallocationand（Diskscheduling）.

10、Systemcallscanbegroupedroughlyintofivemajorcategories:

processcontrol,（filemanagement）,devicemanipulation,（Informationmaintenance）,andcommunications.

11、A（process）canbethoughtofasaprograminexecutionwhichwillneedcertainresources-suchasCPUtime,memory,files,andI/Odevices-toaccomplishitstask.

12、Twocommontechniquesforloadingexecutablefilesare（double-clicking）aniconrepresentingtheexecutablefileandenteringthenameoftheexecutablefileonthe（commandline）.

13、Asaprocessexecutes,itchangesstatefromnewstate,（runningstate）,waitingstate,（readystate）,terminatedstate.

14、Theobjectiveofmultiprogrammingistohavesomeprocessrunningatalltimes,tomaximize（CPU）utilization.

15、Asprocessesenterthesystem,theyareputintoa（job）queue,whichconsistsofallprocessesinthesystem.

16、Thelong-termscheduler,or（jobscheduler）,selectsprocessesfromthispoolandloadsthemintomemoryforexecution.

17、The（short-term）scheduler,orCPUscheduler,selectsfromamongtheprocessesthatarereadytoexecuteandallocatestheCPUtooneofthem.

18、Theprimarydistinctionbetweenthelong-termschedulerandtheshort-termschedulerschedulersliesin（frequency）ofexecution.

19、Whenaninterruptoccurs,thesystemneedstosavethecurrent（context）oftheprocesscurrentlyrunningontheCPUsothatitcan（restore）thatcontextwhenitsprocessingisdone,essentiallysuspendingtheprocessandthen（resuming）it.

20、Thecontextisrepresentedinthe（PCB）oftheprocess;

itincludesthevalueoftheCPUregisters,the（processstate）andmemory-managementinformation.

21、SwitchingtheCPUtoanotherprocessrequiresperformingastatesaveofthecurrentprocessandastaterestoreofadifferentprocess.Thistaskisknownasa（contextswitch）.

22、Aprocessmaycreateseveralnewprocesses,viaacreate-process（systemcall）,duringthecourseofexecution.Thecreatingprocessiscalledaparentprocess,andthenewprocessesarecalledthe（children）ofthatprocess.

23、Aprocessterminateswhenitfinishesexecutingitsfinalstatementandaskstheoperatingsystemtodeleteitbyusingthe（exit（））systemcall.

24、Aprocessisindependentifitcannotaffectorbeaffectedby（theotherprocesses）executinginthesystem.

25、Theadvantagesofprocesscooperationinclude（information）,computationspeed-up,modularityandconvenience.

26、Withindirectcommunication,themessagesaresenttoandreceivedfrommailboxes,orportswhichcanbeviewedabstractlyasanobjectintowhichmessagescanbeplacedbyprocessesandfromwhichmessagescanberemoved.

27、Messagepassingmaybeeitherblockingor（nonblocking）alsoknownas（synchronous）andasynchronous.

28、Whethercommunicationisdirectorindirect,messagesexchangedbycommunicatingprocessesresideinatemporaryqueues.Basically,suchqueuescanbeimplementedinthreeways:

（Zerocapacity）,（Bounded）andunboundedcapacity.

29、A（thread）isabasicunitofCPUutilization;

ItcomprisesathreadID,aprogramCounter,aregisterset,andastack.

30、A（traditional）（orheavyweight）processhasa（single）threadofcontrol.Ifaprocesshasmultiplethreadsofcontrol,itcanperformmorethanonetaskatatime.

31、Thebenefitsofmultithreadedprogrammingcanbebrokendownintofourmajorcategories:

（Responsiveness）,（Resource）,Economy,Utilizationofmultiprocessorarchitecture.

32、CPU（scheduling）isthebasisofmulti-programmedoperatingsystems.ByswitchingtheCPUamong（processes）,theoperatingsystemcanmakethecomputermoreproductive.

33、Processexecutionconsistsofacycleof（CPUexecution）andI/Owait.Processesalternatebetweenthesetwostates.

34、DispatchermodulegivescontroloftheCPUtotheprocessselectedbythe（short-term）scheduler;

Thisfunctioninvolves:

（switchingcontext）,switchingtousermode,jumpingtotheproperlocationintheuserprogramtorestartthatprogram.

35、Thetimeittakesforthedispatchertostoponeprocessandstartanotherrunningisknownasthe（dispatchlatency）.

36、ManycriteriahavebeensuggestedforcomparingCPUschedulingalgorithms.Thecriteriaincludethefollowing:

（CPUutilization）,throughput,（turnaroud）time,waitingtime,（Responsetime）.

37、TheSJFalgorithmcanbeeither（preemptive）ornonpreemptivewhichgivesminimum（averagewaiting）timeforagivensetofprocesses.

38、Amajorproblemwithpriorityschedulingalgorithmsisindefiniteblocking,orstarvation.Asolutiontotheproblemis（aging）.

39、The（roundrobin）schedulingalgorithmisdesignedespeciallyfor（time-sharingsystem）.ItissimilartoFCFSscheduling,butpreemptionisaddedtoswitchbetweenprocesses.

40、Asituationlikethis,whereseveralprocessesaccessandmanipulatethesamedataconcurrentlyandtheoutcomeoftheexecutiondependsontheparticularorderinwhichtheaccesstakesplace,iscalleda（racecondition）.

41、Considerasystemconsistingofnprocesses{PO,PI,...,Pn-1）.Eachprocesshasasegmentofcode,calleda（critical）,inwhichtheprocessmaybechangingcommonvariables,updatingatable,writingafile,andsoon.

42、Asolutiontothecritical-sectionproblemmustsatisfythefollowingthreerequirements:

（Mutualexclusion）,Progressand（Boundedwaiting）.

43、Ingeneral,wecanstatethatanysolutiontothecritical-sectionproblemrequiresasimpletool-a（lock）.Aprocessmustacquireitbeforeenteringacriticalsection.

44、Thevarioushardware-basedsolutionstothecritical-sectionproblemarecomplicatedforapplicationprogrammerstouse.Toovercomethisdifficulty,wecanuseasynchronizationtoolcalleda（semaphore）.

45、AsemaphoreSisanintegervariablethat,apartfrominitialization,isaccessedonlythroughtwostandardatomicoperations:

（wait（））and（signal（））.

46、Themaindisadvantageofthesemaphoredefinitiongivenhereisthatitrequires（busywaiting）.

47、Dispatcherobjectsmaybeineitherasignaledstateoranonsignaledstate.A（signaledstate）indicatesthatanobjectisavailableandathreadwillnotblockwhenacquiringtheobject.

48、Sometimes,awaitingprocessisneveragainabletochangestate,becausetheresourcesithasrequestedareheldbyotherwaitingprocesses.Thissituationiscalleda（deadlock）.

49、Asystemconsistsofafinitenumberofresourcestobedistributedamonganumberof（competingprocesses）.Theresourcesarepartitionedintoseveraltypes,eachconsistingofsomenumberofidentical（instances）.

50、Underthenormalmodeofoperation,aprocessmayutilizearesourceinonlythefollowingsequence:

（Request）,use,（Release）.

60、Multithreadedprogramsaregoodcandidatesfordeadlockbecausemultiplethreadscancompetefor（sharedresources）.

61、Deadlockcanariseiffourconditionsholdsimultaneously:

Mutualexclusion

（Holdandwait）,Nopreemption,（Circularwait）.

62、Deadlockscanbedescribedmorepreciselyintermsofadirectedgraphcalleda（systemresourceallocation）graph.ThisgraphconsistsofasetofverticesVandasetofedgesE.

63、Themainpurposeofacomputersystemistoexecuteprograms.Theseprograms,togetherwiththedatatheyaccess,mustbein（mainmemory）（atleastpartially）duringexecution.

64、Mainmemoryand（registers）areonlystorageCPUcanaccessdirectly.

65、Thebaseregisterholdsthesmallestlegal（physicalmemoryaddress）;

thelimitregisterspecifiesthesizeoftherange.

66、Addressbindingofinstructionsanddatatomemoryaddressescanhappenatthreedifferentstages:

（Compiletime）,Loadtime,（Executiontime）.

67、Logicalandphysicaladdressesarethesameincompile-timeand（load-time）address-bindingschemes;

logicalandphysicaladdressesdifferin（execution-time）address-bindingscheme.

68、InMMUscheme,thevalueintherelocationregisterisaddedtoeveryaddressgeneratedbyauserprocessatthetimeit