基于泊松分布的-CPU-调度算法仿真(IJMSC-V6-N2-4)

I.J.MathematicalSciencesandComputing,2020,2,71-78PublishedOnlineApril2020inMECS()DOI:10.5815/ijmsc.2020.02.04Availableonlineat:02November2019;Accepted:28December2019;Published:08April2020AbstractNumerousschedulingalgorithmshavebeendevelopedandimplementedinabidtooptimizedCPUutilization.However,selectingaschedulingalgorithmforrealsystemisstillverychallengingasmostofthesealgorithmshavetheirpeculiarities.Inthispaper,acomparativeanalysisofthreeCPUschedulingalgorithmsShortestJobFirstNon-Preemptive,DynamicRound-Robineven-oddnumberquantumSchedulingalgorithmandHighestResponse-Ratio-Next(HRRN)wascarriedoutusingdatasetgeneratedusingPoissonDistribution.TheperformanceofthesealgorithmswasevaluatedinthecontextofAverageWaitingTime(AWT),AverageTurnaroundTime(ATT).ExperimentalresultsshowedthatShortestJobFirstNon-Pre-emptiveresultedinminimalAWTandATTwhencomparedwithtwootheralgorithms.IndexTerms:Poissondistribution,ShortestJobFirstNon-Preemptive,DynamicRound-Robineven-oddnumberquantumSchedulingalgorithm,HighestResponse-Ratio-Next.©2020PublishedbyMECSPublisher.Selectionand/orpeerreviewunderresponsibilityoftheResearchAssociationofModernEducationandComputerScience*Correspondingauthor.E-mailaddress:72SimulationofCPUSchedulingAlgorithmsusingPoissonDistribution1.IntroductionOneofthemostexpensiveresourcestheoperatingsystemhastomanageinacomputersystemistheCentralProcessingUnit(CPU).Inamulti-programmingandsingleprocessorenvironment,thesingleprocessorissharedamongtheseprocessesfollowingsomeCPUschedulingalgorithm.CPUschedulingistheprocesswherebyoneprocessisallowedtousetheCPUwhiletheexecutionofanotherprocessisonhold(waitingforanI/Ooraninterrupt)therebymakingfullutilizationoftheCPU[5].ThegoalofCPUschedulingistomaximizeCPUutilizationbyreducingprocessresponsetime,waitingtime,turnaroundtimeandnumberofcontextswitches.Inabidtofindthebestwayofschedulingprocessesforexecution,numerousCPUschedulingalgorithmshavebeendevelopedandimplementedsomeofwhicharepreemptive,whileothersarenon-preemptive.Inapreemptivescheduling,aprocesswithahigherprioritycanblockthecurrentlyrunningprocess,whileinanon-preemptiveschedulingalgorithm,oncetheCPUisallocatedtoaprocess,theprocessmustterminatebeforethenextprocesswillhavechancetorun.Mostoftheseschedulingalgorithmshavetheirprosandcons,consequently,choosingaschedulingalgorithmforarealsystembecomesaproblem.Toovercomethisproblem,numerousalgorithmevaluationtechniqueshavebeenproposed.Inviewoftheabove,thisstudyisemployingthesimulationtechniqueofalgorithmevaluationtoinvestigatetheperformanceofthreeschedulingalgorithmsnamelyShortestJobFirstNon-Preemptive,DynamicRound-Robineven-oddnumberquantumSchedulingalgorithmandHighestResponse-Ratio-Next(HRRN).1.1CPUSchedulingInamultiprogrammingenvironment,theCPUmustbesharedamongthemultipleprocessesfollowingsomeschedulingalgorithm.ThetaskofdeterminingwhentheprocessorshouldbeassignedandtowhichprocessandforhowlongiscalledCPUscheduling.ThegoalofCPUschedulingistomaximizeCPUutilization(keeptheCPUbusyallthetime)soastomaximizesystemthroughput.Andbydoingso,reducingprocessresponsetime,waitingtime,turnaroundtimeandnumberofcontextswitches.1.2CPUSchedulingAlgorithmsNumerousSchedulingalgorithmhavebeendevelopedandimplemented.Someoftheseinclude:1.2.1ShortestJobFirstNon-PreemptiveSchedulingalgorithmShortestjobfirst(SJF)orshortestjobnext,isaplanningarrangementthatchoosestheholdingupprocedurewiththelittlestexecutiontimetoexecutenext.SJNisanon-preemptivealgorithm.Non-preemptive:Wecan'texpelaprocedureuntilitfinishesitexecution.•ShortestJobfirsthasthebenefitofhavingleastnormalwaitingtimeamongallschedulingalgorithms.•ItisaGreedyAlgorithm.•Itmaycausestarvationifshorterprocedurescontinuecoming.Thisissuecanbetackledutilizingtheideaofaging.•ItisforallintentsandpurposesinfeasibleasOperatingSystemmaynotrealizebursttimeandthereforemaynotsortthem.Whileitisbeyondtherealmofimaginationtoexpecttoforeseeexecutiontime,afewtechniquescanbeutilizedtoappraisetheexecutiontimeforajob,forexample,aweightednormalofpastexecutiontimes.SJFcanbeutilizedinparticularconditionswherepreciseevaluationsofrunningtimeareaccessible.SimulationofCPUSchedulingAlgorithmsusingPoissonDistribution731.2.2HighestResponse-Ratio-Next(HRRN)SchedulingalgorithmRoundRobinschedulingisapreemptivetypeofFCFS.InRRscheduling,formsarelikewisedispatchedinFIFOsuccessionhowevereachprocedureispermittedtorununiquelyforaconstrainedmeasureoftime.InthisDynamicRound-Robineven-oddnumberquantumSchedulingalgorithm,two-timequantum'sTQ1andTQ2isdetermined.WhereTQ1isthebursttimeoftheconsiderablenumberofproceduresatevenplacesinthepreparedlineandTQ2isthenormalbursttimeoftheconsiderablenumberofprocessesatoddplacesinthepreparedline[6].Atthatpointweanalyzethetwotimequantum's,togetthemoreprominentTimeQuantum.Takemoreprominenttimeasaperiodquantumandapplytoeachprocedure.I