操作系統(tǒng)概念第七版答案含編程代碼

1、Operatingsystemconcepts(Seventhedition)2008.3solutionstotheexercisesChapter11.1Inamultiprogrammingtimesharingenvironmentseveraluserssharethesystemsimultaneously.Thissituationcanresultinvarioussecurityproblems.a.Whataretw

2、osuchproblemsb.CanweensurethesamedegreeofsecurityinatimesharedmachineasinadedicatedmachineExplainyouranswer.Answer:a.Stealingcopyingone’sprogramsdatausingsystemresources(CPUmemydiskspaceperipherals)withoutproperaccountin

3、g.b.Probablynotsinceanyprotectionschemedevisedbyhumanscaninevitablybebrokenbyahumanthemecomplextheschemethemedifficultitistofeelconfidentofitscrectimplementation.1.2Theissueofresourceutilizationshowsupindifferentfmsindif

4、ferenttypesofoperatingsystems.Listwhatresourcesmustbemanagedcarefullyinthefollowingsettings:a.Mainframeminicomputersystemsb.Wkstationsconnectedtoserversc.HheldcomputersAnswer:a.Mainframes:memyCPUresourcesstagewkbwidth.b.

5、Wkstations:memyCPUresoucesc.Hheldcomputers:powerconsumptionmemyresources.1.3UnderwhatcircumstanceswouldauserbebetteroffusingatimesharingsystemratherthanaPCsingleuserwkstationAnswer:Whentherearefewotherusersthetaskislarge

6、thehardwareisfasttimesharingmakessense.Thefullpowerofthesystemcanbebroughttobearontheuser’sproblem.Theproblemcanbesolvedfasterthanonapersonalcomputer.Anothercaseoccurswhenlotsofotherusersneedresourcesatthesametime.Aperso

7、nalcomputerisbestwhenthejobissmallenoughtobeexecutedreasonablyonitwhenperfmanceissufficienttoexecutetheprogramtotheuser’ssatisfaction.1.4Whichofthefunctionalitieslistedbelowneedtobesupptedbytheoperatingsystemfthefollowin

8、gtwosettings:(a)hhelddevices(b)realtimesystems.a.Batchprogrammingb.Virtualmemyc.TimesharingOperatingsystemconcepts(Seventhedition)2008.3Fexamplelet’sconsiderasystemofnodesthatsharecookingrecipes.Undertheclientservermodel

9、allrecipesarestedwiththeserver.Ifaclientwishestoaccessarecipeitmustrequesttherecipefromthespecifiedserver.Usingthepeertopeermodelapeernodecouldaskotherpeernodesfthespecifiedrecipe.Thenode(perhapsnodes)withtherequestedrec

10、ipecouldprovideittotherequestingnode.Noticehoweachpeermayactasbothaclient(i.e.itmayrequestrecipes)asaserver(itmayproviderecipes.)1.8Consideracomputingclusterconsistingoftwonodesrunningadatabase.Describetwowaysinwhichthec

11、lustersoftwarecanmanageaccesstothedataonthedisk.Discussthebenefitsdisadvantagesofeach.Answer:Considerthefollowingtwoalternatives:asymmetricclusteringparallelclustering.Withasymmetricclusteringonehostrunsthedatabaseapplic

12、ationwiththeotherhostsimplymonitingit.Iftheserverfailsthemonitinghostbecomestheactiveserver.Thisisappropriatefprovidingredundancy.Howeveritdoesnotutilizethepotentialprocessingpowerofbothhosts.Withparallelclusteringthedat

13、abaseapplicationcanruninparallelonbothhosts.Thedifficultyimplementingparallelclustersisprovidingsomefmofdistributedlockingmechanismffilesontheshareddisk.1.9HowarewkcomputersdifferentfromtraditionalpersonalcomputersDescri

14、besomeusagescenariosinwhichitisadvantageoustousewkcomputers.Answer:Awkcomputerreliesonacentralizedcomputerfmostofitsservices.Itcantherefehaveaminimaloperatingsystemtomanageitsresources.Apersonalcomputerontheotherhhastobe

15、capableofprovidingalloftherequiredfunctionalityinastalonemannerwithoutrelyingonacentralizedmanner.Scenarioswhereadministrativecostsarehighwheresharingleadstomeefficientuseofresourcesarepreciselythosesettingswherewkcomput

16、ersarepreferred.1.10WhatisthepurposeofinterruptsWhatarethedifferencesbetweenatrapaninterruptCantrapsbegeneratedintentionallybyauserprogramIfsofwhatpurposeAnswer:Aninterruptisahardwaregeneratedchangeofflowwithinthesystem.

17、Aninterrupthlerissummonedtodealwiththecauseoftheinterruptcontrolisthenreturnedtotheinterruptedcontextinstruction.Atrapisasoftwaregeneratedinterrupt.AninterruptcanbeusedtosignalthecompletionofanIOtoobviatetheneedfdevicepo