会员注册 | 登录 | 微信快捷登录 支付宝快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

47-How to Make a Multiprocessor Computer That Correctly Executes Multiprocess Programs.pdf47-How to Make a Multiprocessor Computer That Correctly Executes Multiprocess Programs.pdf -- 5 元

宽屏显示 收藏 分享

资源预览需要最新版本的Flash Player支持。
您尚未安装或版本过低,建议您

IEEETRANSACTIONSONCOMPUTERS,VOL.C28,NO.9,SEPTEMBER1979REFERENCES1C.Black,C.E.Sundberg,andW.K.S.Walker,Developmentofaspacebornememorywithasingleerroranderasurecorrectionscheme,inConf.Rec.,1977FaultTolerantComputingSymp.,FTCS7,June1977,pp.5055.2C.Blacketal.,Highlyreliablesemiconductormemoryfortheonboardcomputer,FinalRep.ESTECContr.2528/75/HP,BritishAircraftCorp.,Bristol,England.3R.W.Lucky,J.Salz,andE.J.Weldon,Jr.,PrinciplesofDataCommunication.NewYorkMcGrawHill,1968.4W.W.PetersonandE.J.Weldon,Jr.,ErrorCorrectingCodes,2ndEd.Cambridge,MAMITPress,1972.5M.Y.Hsiao,AclassofoptimalminimumoddweightcolumnSEC/DEDcodes,IBMJ.Res.Develop.,pp.395401,July1970.6G.Longo,AlgebraiccodingandcombinatoricsAtutorialsurvey,NATOAdvancedStudyInstitute,Darlington,England,Aug.820,1977,Conf.Rec.,SijthoffNoordhoff,1978,seriesE,no.25,pp.151169.7E.R.Berlekamp,AlgebraicCodingTheory.NewYorkMcGrawHill,1968.8R.P.Capece,Memoryrichminisgetaggressive,Electronics,pp.6970,Aug.18,1977.9H.J.HelgertandR.D.Stinaff,Minimumdistanceboundsforbinarylinearcodes,IEEETrans.InformationTheory,vol.IT19,pp.344356,May1973.10C.E.Sundberg,Sometransparentshortenedcodesforsemiconductormemories,TelecommunicationTheory,Univ.ofLund,Lund,Sweden,Tech.Rep.TR91,Sept.1977.11Erasuresanderrorsdecodingforsemiconductormemories,IEEETrans.Comput.,vol.C27,pp.696705,Aug.1978.12W.C.CarterandC.E.McCarthy,Implementationofanexperimentalfaulttolerantmemorysystem,IEEETrans.Comput.,vol.C25,pp.557568,June1976.ofeachindividualprocessordoesnotguaranteethatthemultiprocessorcomputerissequentiallyconsistent.Inthisbriefnote,wedescribeamethodofinterconnectingsequentialprocessorswithmemorymodulesthatinsuresthesequentialconsistencyoftheresultingmultiprocessor.Weassumethatthecomputerconsistsofacollectionofprocessorsandmemorymodules,andthattheprocessorscommunicatewithoneanotheronlythroughthememorymodules.Anyspecialcommunicationregistersmayberegardedasseparatememorymodules.Theonlyprocessoroperationsthatconcernusaretheoperationsofsendingfetchandstorerequeststomemorymodules.Weassumethateachprocessorissuesasequenceofsuchrequests.Itmustsometimeswaitforrequeststobeexecuted,butthatdoesnotconcernus.Weillustratetheproblembyconsideringasimpletwoprocessmutualexclusionprotocol.Eachprocesscontainsacriticalsection,andthepurposeoftheprotocolistoinsurethatonlyoneprocessmaybeexecutingitscriticalsectionatanytime.Theprotocolisasfollows.process1ifb0thencriticalsectionelse...fiHowtoMakeaMultiprocessorComputerThatCorrectlyExecutesMultiprocessProgranmLESLIELAMPORTAbstractManylargesequentialcomputersexecuteoperationsinadifferentorderthanisspecifiedbytheprogram.Acorrectexecutionisachievediftheresultsproducedarethesameaswouldbeproducedbyexecutingtheprogramstepsinorder.Foramultiprocessorcomputer,suchacorrectexecutionbyeachprocessordoesnotguaranteethecorrectexecutionoftheentireprogram.Additionalconditionsaregivenwhichdoguaranteethatacomputercorrectlyexecutesmultiprocessprograms.IndexTermsComputerdesign,concurrentcomputing,hardwarecorrectness,multiprocessing,parallelprocessing.Ahighspeedprocessormayexecuteoperationsinadifferentorderthanisspecifiedbytheprogram.Thecorrectnessoftheexecutionisguaranteediftheprocessorsatisfiesthefollowingconditiontheresultofanexecutionisthesameasiftheoperationshadbeenexecutedintheorderspecifiedbytheprogram.Aprocessorsatisfyingthisconditionwillbecalledsequential.Consideracomputercomposedofseveralsuchprocessorsaccessingacommonmemory.Thecustomaryapproachtodesigningandprovingthecorrectnessofmultiprocessalgorithms13forsuchacomputerassumesthatthefollowingconditionissatisfiedtheresultofanyexecutionisthesameasiftheoperationsofalltheprocessorswereexecutedinsomesequentialorder,andtheoperationsofeachindividualprocessorappearinthissequenceintheorderspecifiedbyitsprogram.Amultiprocessorsatisfyingthisconditionwillbecalledsequentiallyconsistent.ThesequentialityManuscriptreceivedSeptember28,1977revisedMay8,1979.TheauthoriswiththeComputerScienceLaboratory,SRIInternational,MerlsPark,CA94025.process2b1ifa0thencriticalsectionb0else..fiTheelseclausescontainsomemechanismforguaranteeingeventualaccesstothecriticalsection,butthatisirrelevanttothediscussion.Itiseasytoprovethatthisprotocolguaranteesmutuallyexclusiveaccesstothecriticalsections.Devisingaproofprovidesaniceexerciseinusingtheassertionaltechniquesof2and3,andislefttothereader.Hence,whenthistwoprocessprogramisexecutedbyasequentiallyconsistentmultiprocessorcomputer,thetwoprocessorscannotbothbeexecutingtheircriticalsectionsatthesametime.Wefirstobservethatasequentialprocessorcouldexecutetheb1andfetchboperationsofprocess1ineitherorder.Whenprocesslsprogramisconsideredbyitself,itdoesnotmatterinwhichorderthesetwooperationsareperformed.However,itiseasytoseethatexecutingthefetchboperationfirstcanleadtoanerrorbothprocessescouldthenexecutetheircriticalsectionsatthesametime.Thisimmediatelysuggestsourfirstrequirementforamultiprocessorcomputer.RequirementRlEachprocessorissuesmemoryrequestsintheorderspecifiedbyitsprogram.SatisfyingRequirementRIiscomplicatedbythefactthatstoringavalueispossibleonlyafterthevaluehasbeencomputed.Aprocessorwilloftenbereadytoissueamemoryfetchrequestbeforeitknowsthevaluetobestoredbyaprecedingstorerequest.Tominimizewaiting,theprocessorcanissuethestorerequesttothememorymodulewithoutspecifyingthevaluetobestored.Ofcourse,thestorerequestcannotactuallybeexecutedbythememorymodule,untilitreceivesthevaluetobestored.00189340/79/0900069000.75C1979IEEE690IEEETRANSACTIONSONCOMPUTERS,VOL.c28,NO.9,SEPTEMBER1979RequirementRIisnotsufficienttoguaranteecorrectexecution.Toseethis,supposethateachmemorymodulehasseveralports,andeachportservicesoneprocessororI/Ochannel.Letthevaluesofaandbbestoredinseparatememorymodules,andconsiderthefollowingsequenceofevents.1Processor1sendsthea1requesttoitsportinmemorymodule1.ThemoduleiscurrentlybusyexecutinganoperationforsomeotherprocessororI/Ochannel.2Processor1sendsthefetchbrequesttoitsportinmemorymodule2.Themoduleisfree,andexecutionisbegun.3Processor2sendsitsb1requesttomemorymodule2.Thisrequestwillbeexecutedafterprocessorlsfetchbrequestiscompleted.4Processor2sendsitsfetcharequesttoitsportinmemorymodule1.Themoduleisstillbusy.Therearenowtwooperationswaitingtobeperformedbymemorymodule1.Ifprocessor2sfetchaoperationisperformedfirst,thenbothprocessescanentertheircriticalsectionsatthesametime,andtheprotocolfails.Thiscouldhappenifthememorymoduleusesaroundrobinschedulingdisciplineinservicingitsports.Inthissituation,anerroroccursonlyifthetworequeststomemorymodule1arenotexecutedinthesameorderinwhichtheywerereceived.Thissuggeststhefollowingrequirement.RequirementR2MemoryrequestsfromallprocessorsissuedtoanindividualmemorymoduleareservicedfromasingleFIFOqueue.Issuingamemoryrequestconsistsofenteringtherequestonthisqueue.ConditionRIimpliesthataprocessormaynotissueanyfurthermemoryrequestsuntilafteritscurrentrequesthasbeenenteredonthequeue.Hence,itmustwaitifthequeueisfull.Iftwoormoreprocessorsaretryingtoenterrequestsinthequeueatthesametime,thenitdoesnotmatterinwhichordertheyareserviced.Note.Ifafetchrequeststhecontentsofamemorylocationforwhichthereisalreadyawriterequestonthequeue,thenthefetchneednotbeenteredonthequeue.Itmaysimplyreturnthevaluefromthelastsuchwriterequestonthequeue.ORequirementsRIandR2insurethatiftheindividualprocessorsaresequential,thentheentiremultiprocessorcomputerissequentiallyconsistent.Todemonstratethis,onefirstintroducesarelationonmemoryrequestsasfollows.DefineABifandonlyif1AandBareissuedbythesameprocessorandAisissuedbeforeB,or2AandBareissuedtothesamememorymodule,andAisenteredinthequeuebeforeBandisthusexecutedbeforeB.ItiseasytoseethatRIandR2implythatisapartialorderingonthesetofmemoryrequests.Usingthesequentialityofeachprocessor,onecanthenprovethefollowingresulteachfetchandstoreoperationfetchesorstoresthesamevalueasifalltheoperationswereexecutedsequentiallyinanyordersuchthatABimpliesthatAisexecutedbeforeB.Thisinturnprovesthesequentialconsistencyofthemultiprocessorcomputer.RequirementR2statesthatamemorymodulesrequestqueuemustbeservicedinaFIFOorder.Thisimpliesthatthememorymodulemustremainidleiftherequestattheheadofitsqueueisastorerequestforwhichthevaluetobestoredhasnotyetbeenreceived.ConditionR2canbeweakenedtoallowthememorymoduletoserviceotherrequestsinthissituation.Weneedonlyrequirethatallrequeststothesamememorycellbeservicedintheorderthattheyappearinthequeue.Requeststodifferentmemorycellsmaybeservicedoutoforder.Sequentialconsistencyispreservedbecausesuchaservicepolicyislogicallyequivalenttoconsideringeachmemorycelltobeaseparatememorymodulewithitsownrequestqueue.Thefactthatthesemodulesmaysharesomehardwareaffectstherateatwhichtheyservicerequestsandthecapacityoftheirqueues,butitdoesnotaffectthelogicalpropertyofsequentialconsistency.Therequirementsneededtoguaranteesequentialconsistencyruleoutsometechniqueswhichcanbeusedtospeedupindividualsequentialprocessors.Forsomeapplications,achievingsequentialconsistencymaynotbeworththepriceofslowingdowntheprocessors.Inthiscase,onemustbeawarethatconventionalmethodsfordesigningmultiprocessalgorithmscannotbereliedupontoproducecorrectlyexecutingprograms.Protocolsforsynchronizingtheprocessorsmustbedesignedatthelowestlevelofthemachineinstructioncode,andverifyingtheircorrectnessbecomesamonumentaltask.REFERENCES1E.W.Dijkstra,Hierarchicalorderingofsequentialprocesses,ActaInformatica,vol.1,pp.115138,1971.2L.Lamport,Provingthecorrectnessofmultiprocessprograms,IEEETrans.SoftwareEng.,vol.SE3,pp.125143,Mar.1977.3S.OwickiandD.Gries,Verifyingpropertiesofparallelprogramsanaxiomaticapproach,Commun.Assoc.Comput.Mach.,vol.19,pp.279285,May1976.CommentsonAnApproachtoHighlyIntegratedComputerMaintainedCellularArraysVISHWANID.AGRAWALAbstractTheabovepaperdescribesmachinesconstructedonfaultylogicarrays.Thesemachinesusesomeorallofthegoodcellsthatformaconnectivecluster.Itispointedoutherethatwhenthefaultycellsarerandomlydistributedoverthearray,thepropagationofafreelyexpandingsignal,whichmustavoidthefaultycells,isapercolationprocess.Thepercolationprocessdeterminesthelimittothesizeofamachineembeddedinafaultyarray.Someusefulcharacteristicsofthisprocessarediscussed.IndexTermsCellulararrays,faultsinlogicarrays,percolationprocess,programmablelogic,randomprocesses.Manning,inarecentpaper,hasdescribedtheembeddedmachineswhichareconfiguredinalogicarraycontainingsomeflawedcells.Inarectangulararray,eachcellcommunicatesthroughitsfourneighborsandhencebecomesinaccessibleifallthefourneighborsareflawed.Theembeddedmachinethususesaconnectiveclusteroflogiccellsboundedwithinthearrayboundariesandtheflawedcells.Asthenumberofflawedcellsincreases,thesizeofagoodcellclusterbecomesrestricted.Thepurposeofthiscommunicationistoillustratethattheformationofanembeddedclusterinanarrayofflawedcellsisapercolationprocesswhichhasbeenextensivelystudiedintheliterature1.ManuscriptreceivedNovember20,1977revisedApril20,1979.TheauthorwaswithTRWDefenseandSpaceSystemsGroup,RedondoBeach,CA90278.HeisnowwiththeBellLaboratories,MurrayHill,NJ07974.IF.B.Manning,IEEETrans.Comput.,vol.C26,pp.536552,June1977.00189340/79/0900069100.75C1979IEEE691
编号:201401051948356820    大小:465.94KB    格式:PDF    上传时间:2014-01-05
  【编辑】
5
关 键 词:
工业、机械、能源、设计、建模、模具、工学
温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

当前资源信息

4.0
 
(2人评价)
浏览:20次
baixue100上传于2014-01-05

官方联系方式

客服手机:13961746681   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

相关资源

相关资源

相关搜索

工业、机械、能源、设计、建模、模具、工学  
关于我们 - 网站声明 - 网站地图 - 友情链接 - 网站客服客服 - 联系我们
copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5