2024年-DMSA簡介演示幻燈片

HowandWhyToUsePrimeTime’sDistributedMulti-ScenarioAnalysis2015-04-091AboutThisPresentationThispresentationexplores:WhypeopleneedmultipleSTAanalysisHowtheyaresometimescombinedtogetherTheadvantagesanddisadvantagesofmerginganalysistogetherversusanalyzingthemseparatelyHowPrimeTime’sDMSAcanhelpyougetthemostaccurateanalysis,inlesstime,withlessusereffort,andfewerresources2WhereMultiAnalysisComeFromThetwoprimarycausesofmultipleanalysisMultipleoperatingmodesMultipleanalysiscornersWhatarethey?3WhereMultiAnalysisComeFromAdesigntypicallyhasmultipleoperatingmodesMultiplemissionmodesDifferentclockfrequencesDifferentclockmuxingconfigurationsDifferentconfigurationconstantstocontrollogicbehavioretc…MultipletestmodesATPGscanBISTmodesJTAGmodesetc…4WhereMultiAnalysisComeFromAdesignmustreliablyoperateacrossItsspecifiedrangeofvoltage/temperature(VT)conditions:thechip’senviromentTherangeofpossibleprocess/interconnect(P)conditions:thechip’smanufacturingcharacteristicsAspecificsetofconditions(PVT)iscalledaconner5WhereMultiAnalysisComeFromSTAmustpassineveryoperatingmodeundereveryPVTconnerconditionThesetermsmultiply:That’salotofanalysis!6DifficultiesOfMultiAnalysisManagingmultipleoperatingmodesacrossmultiplecornersisdifficultMustmanagemultiplePrimeTimeruns…Mustanalyzelotsofreports…Ifthereareviolations…wheredowestart?7WhatToDO?Designerssometimestrytoreducethenumberofrunsusingvarioustechniques:Skippingcertainmode/cornercombinationsentirelyLimitingcornercombinationsandaddingmoremarginCombiningsimilaroperatingmodestogether8WhatToDO?ThefirsttwoaresimplyomissionsofcorneranalysisbasedonengineeringjudgmentNotageneralwayanddonotrecommended!Thethird–whethertocombineoperatingmodestogetherorkeepthemseparate–isourfocusLet’stalkmoreaboutthis…9CombiningModes:AnExampleConsiderthefollowingexamplecircuit:10CombiningModes:AnExampleAnalyzedseparately,caseanalysisisusedtoselecttheappropriateclockforeachmode11CombiningModes:AnExampleAnalyzedtogether,wecouldcombinethesemodestogetherwiththefollowingcommands:Needset_clock_groupstopreventCLK250←→CLK33012CombiningModes:LimitationsOnthesurface,itseemslikecombingmodesisthewaytogo!FewerrunstogetthesameamountofworkdoneHowever,therearedrawbackstocombiningmodesTimingpessimismIncreasedmemory/runtime13CombiningModes:slewpropagationpessimismPrimeTimecomputesbothminandmaxtimingforeverytimingarcinthedesignFastslewsalwayspropagatedformin-delaycomputationSlowslewsalwayspropagatedformax-delaycomputation14CombiningModes:slewpropagationpessimismWhenthemodesareanalyzedseparately:Theclockbuffershaveslowminandmaxdelaysinmode0Theclockbuffershavefastminandmaxdelaysinmode115CombiningModes:slewpropagationpessimismHowever,whenthemodesareanalyzedtogether,bothclockspropagatedintothenetwork:TheslowCLK250slew(red)isusedformax-delaypropagationThefastCLK333slew(green)isusedformin-delaypropagation16CombiningModes:slewpropagationpessimismSetuppathsusemax-delaylaunch,min-delaycaptureForsetuppathinCLK250domain,captureispessimisticForsetuppathinCLK333domain,launchispessimistic17CombiningModes:crosstalkSIinteractions(example#1)Whenthemodesareanalyzedseparately:Onlyasinglefrequencyclockispresentonn1andn2Theedgeonn1isalwayslaterthantheedgeonn2Overlapcanneveroccur,sonodeltadelaysoccuroneithernet18CombiningModes:crosstalkSIinteractions(example#1)Whenthemodesareanalyzedtogether:BothclocksareseenonbothnetsCrosstalkinteractionsbetweentheclocksareprobableInfact,theyareacertaintyiftheclocksareasynchronous

19CombiningModes:crosstalkSIinteractions(example#2)Whenthemodesareanalyzedtogether:Slewmergingpessimismcausesthemin/maxtimingofbuffersU1-U3towidenn1isattackedbyn2althoughitcouldn’thappenineithermodeNowthewindow/slewsonn3pessimisticallyattackn4…20PessimismFromCombiningModes:WhatHaveWeLearned?Whendifferentmodesaremergedtogether:SlewmeringpessimismoccursSIpessimismacrossclockoccursWindowmergingpessimismwithinclockdomainoccursTheseeffectsinteractandcompoundTheresultingmerged-modetimingismorepessimisticthananyoftheoriginalmodesTheresultinganalysisissafebutpessimisticPrimeTimeisdoingtherightthing,butwithpessimisticinputWehaveindeedreducedthenumberofruns,butatanaccuracycost21CombiningModes:

AnalysisMemory/RuntimeWhencombiningrunstogether,memoryandruntimeincreaseTounderstandwhy,let’slookathowPrimeTimestoresthetimingdataforthefollowingexamplecircuit:22CombiningModes:

AnalysisMemory/RuntimeArrivaltimesarecomputedperclockdomain23CombiningModes:

AnalysisMemory/RuntimeAswecombinemodesandaddmoreclocks:MoretimeisneededforextradelaycalculationsandclockpropagationMorememoryisneededtostoreeachclock’sarrivalsWehaveindeedreducedthenumberofruns,butatamemory,runtimeandaccuracycostWeneedamethodwhichcanmergemultiruns,buteachrunsdonotinteractwiththeothersLet’sintroduceanewmethodDMSA…24WhatisDistributedMulti-ScenarioAnalysis(DMSA)?DMSAprovidesefficientanalysisofmultiplePrimeTimeanalysis(orscenarios)fromasinglemasterPrimeTimeWecanworkwithmultipleanalysisaseasilyaswithasinglePrimeTimeanalysisrun!25DMSA:masterprocessTheDMSAmasterprocessisthept_shellinvokedbytheuserThemasteristheuser’spointofcontactThemasterinvokestheremoteslaveprocessesThemasterissuestaskstotheremoteprocesses,andcollectstheresultingdata26InvokingthemasterprocessTheDMSAmasterprocessisinvokedwiththe–multi-scenarioswitch:Thismasterpt_shellisaspecialDMSAcontrolshell:DifferentcommandsDifferentwarnings/errorsDifferentmanpagesDoesnotrequieanextralicense27DMSA:remoteprocessTheremoteprocessisaremotePrimeTimeprocessthatiscontrolledbythemasterAslaveisalsorefferedtoasaslaveprocessItiscreatedbythemaster,andisgiventaskstocompletebythemasterAtanygiventime,aslaveprocesscanonlybeperformingataskonasignlescenario28DMSAUsesIndependentAccurateAnalysisEachscenarioinaDMSArunisafullPrimeTimeanalysiswhichcanhaveitsownunique:DelayandslewtimingDetailedparasiticsPrimeTimevariablesettings29SettingUpDMSA TosetupaDMSArun,threekeycomponentsmustbeconfigured:NumberoflicensesNumberofremoteslaveprocessesScenariodefinitionsLet’stakealookathowtheseareconfigured30SettingUpDMSA:configuringlicensesWegiveDMSAtheupperlimitforthenumberoflicensestouseAminimumofoneisneededtodoanyworkAdditionallicensesarepulledfromthelicenseseverasneededThemasterdoesnotrequireanextralicenseIntheexamplebelow,weallowDMSAupto4PrimeTimeandPrimeTime-SIlicenses31SettingUpDMSA:

ConfiguringRemoteProcessesWegiveDMSAinformationontheremoteprocessestoinvokeMax_cores,specifytheCPUcoresusagelimitforthecurrentrunNum_process,specifythenumberofprocessestolaunchIntheexamplebelowWeaskDMSAtoinvoke8processeswith8CPUcoresset_host_options–max_cores8–num_processes832SettingUpDMSA:DefiningScenariosTheanalysisscenariosaredefinedinoneoftwoways:ProvidingPrimeTimescriptswhichload/constraintheanalysis:ProvidingexistingPrimeTimesavedsessions:33SettingUpDMSA:DefiningScenariosUsingScriptsIfyouhaveadifferentscriptforeachscenario,justpointtotheproperscriptforthatscenariodefinition34SettingUpDMSA:DefiningScenariosUsingScriptsThemorecommoncaseisasingleanalysisscriptusingvariablestocontrolwhichmode/cornerisanalyzedBelow,modeandcornercontroltheanalysis35SettingUpDMSA:DefiningScenariosUsingScriptsInthiscase,wesimplyvarythesevariablesacrosstheirdifferentcombinationsandcreatescenarios:The–specific_variablesoption“pushes”avariable’scurrentmastervalueintothescenarioHowdoesthiswork?36SettingUpDMSA:DefiningScenariosUsingScriptsUsing–specific_variablesinascenariodefinitioncanbethoughtofas:InvokingaPrimeTimesessionSettingthespecifiedvariablesSourcingthescenarioscript37SettingUpDMSA:DefiningScenariosUsingsessionsYoucanalsodefinescenarioswithsavedsessions:38FlexiblelicensemanagementWhen(#licenses)<(#remoteprocesses):ThemasterdistributeslicensestotheremoteprocessesWhenataskfinishesataremoteprocess,thelicenseisfreedtobeimmediatelyusedbyanotherprocess39Flexiblemachinemanagement When(#remoteprocesses)<(#scenarios)ScenarioimagesmustbeswappedtodisktoexecutethetaskacrossallscenariosThisisexpensiveintermsofdiskactivityandruntimeThisshouldbeavoidedunlessabsolutelynecessary40MergedReportingWehaveseenthatDMSAletsuseasilyrunallscenariostogetherThebigpayoffisthatwecanalsoeasilyanalyzeallscenariostogetherTheeasiestmethodisusingmergedreporting,wherewecanissuereportingcommandsacrossallscenariosThemergedreportingcommandsinclude:Report_timingReport_constraintReport_analysis_coverageReport_clock_timingReport_si_bottleneck41Mergedreport_timingToseethe10worstpathsineachpathgroupsacrossallscenarios,wesimplyissue:DMSAautomaticallymergestheresultsacrossallscenarios,savingusfromshiftingthroughhundredsofnearlyidenticalreportsTopologicalduplicatesareautomaticallyremoved42Mergedreport_timing

MergedreportstypicallyincludethescenarionameinthereportBelowisatimingreportfromreport_timing43DMSA:AutomaticallyECOfixingAlltheusualECOcommandsareavaliable:size_cellinsert_