copyright c01027

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1、UNIVERSITYofCALIFORNIASANTACRUZMANAGINGTHESOFTREAL-TIMEPROCESSESINRBEDAprojectreportsubmittedinpartialsatisfactionoftherequirementsforthedegreeofMASTEROFSCIENCEinCOMPUTERSCIENCEbyCaixueLinMarch2003TheprojectreportofCaixueLinisapproved:ProfessorScottA.BrandtProfessorEthan

2、L.MillerCopyrightcbyCaixueLin2003AbstractManagingtheSoftReal-TimeProcessesinRBEDbyCaixueLinThispaperdescribestheimplementationofaResource-rateBasedEarliestDeadlineFirstscheduler(RBED).Theschedulerconsistsoftwoindependentcomponents:aresourceallocationpolicyandascheduling

3、algorithm.Itprovidesuniformschedulingforhardreal-time(HRT),softreal-time(SRT),andnon-real-timeprocesses.Weighted-proportionalResourceAllocationPolicy(WRAP)inRBEDensuresthetotalactualresourceusageofallprocessesisnomorethan1underallsituations.EachHRTprocessreservesafractio

4、noftheresources.SRTprocessesaremanagedtoreceivetheresourcewitharate(fraction)weightedproportionaltotheirtargetresourceusage.WRAPautomaticallyadjuststheresourceshareamongtheSRTprocesseswhentheloadchanges.Non-real-timeprocessesreceiveafairshareoftheleftoverresourcesbyHRTan

5、dSRTprocesses,buttheyneverstarveunderanysituationinRBED.Withresourceusagenomorethan1,theEDF-basedschedulingalgorithminRBEDal-waysfindsafeasiblescheduleforanysetofprocesses.Eachreal-timeprocess(includingHRTandSRT)isscheduledaccordingtoitsdeadline,whichmaybedynamicallyadjus

6、tedbecauseoftheloadchange.Non-real-timeprocessesarescheduledasSRTprocesseswiththeirpseudodeadlinesassignedbythescheduler.TheperformanceresultsdemonstrateRBED'sfeasibility(inunderloadedsituations)andflexibility(inoverloadedsituations)forfullyintegratedschedulingofHRT,SRT,a

7、ndnon-real-timeprocesses.ContentsAbstractiiiListofFiguresviiListofTablesixAcknowledgementsx1Introduction......................................11.1RBED.....................................22ResourceAllocationinRBED............................42.1ResourceDistributionandAdm

8、issionControlinRBED..........42.2ResourceAllocationforSRTprocesses...................63EDFSchedulinginR