研课程要点与复习

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1、高级体系结构课程要点第一章前言计算机技术快速法进步的原因技术进步－－Moore定律发展体系结构发展体系结构演化过程现代计算机体系结构的组成高级计算机体系结构研究范畴计算机系统结构的分类Flynn分类法---定性冯氏分类法---定量第三章Instruction-LevelParallelismandItsDynamicExploitationWhatispipelining?HowisthepipeliningImplemented?Whatmakespipelininghardtoimplement?Howdoe

2、sCPIdescend?CPI=1CPI<1CPI<<1IdealPerformanceforPipeliningIdealspeedupequaltoNumberofpipestagesMIPSinstructionformatWorksintheMIPS5stagepipelineTheMIPSpipeliningPipelinehazard:themajorhurdleStructuralhazardsDatahazardsControlhazardsberesolvedbyStallSolutionima

3、ginableforStructuralhazards“doublebump”InsertstallprovideanothermemoryportsplitinstructionmemoryanddatamemoryuseinstructionbufferfullypipelinedfunctionunitWhyallowmachinewithstructuralhazard?SolutionimaginableforDatahazardsInterlock:insertstallsDetect:DataHaz

4、ardLogicForwarding:reducedatahazardstallscompilertoavoidloadstallSolutionimaginableforControlhazardsMovetheBranchComputationForwardSimplesolutionsFreezeorflushthepipelinePredict-not-taken(Predict-untaken)TreateverybranchasnottakenPredict-takenTreateverybranch

5、astakenDelayedbrancha,b,cCancellingfunctionExtendingtheMIPSPipelinetoHandlecomplexpipelinestructurePipeliningtimeparameterLatencyInitiationintervalTheoutoforderThenewtypesofdatahazardsRAWStallsarisingWAWInstruction-LevelParallelismCPIpipelined=IdealpipelineCP

6、I+pipelinedstallcyclesperinstruction=1+Structualstalls+RAWstalls+WARstalls+WAWstalls+ControlstallsBasicBlockILPisquitesmallDataDependenceandHazardsTrueDataDependence→RAW(Readafterwrite)NamedependenceAnti-dependence→WAR(Writeafterread)Outputdependence→WAW(Writ

7、eafterwrite)SomePropertyaboutDependencesareapropertyofprogramshazardorlengthofanystallisapropertyofthepipeline(hardware)ControlDependenciesBranchBehaviorOvercomingDataHazardswithDynamicSchedulingKeyidea:Allowinstructionsbehindstalltoproceedin-orderissueout-of

8、-orderexecutionout-of-ordercompletionDynamicSchedulingwithaScoreboardIssue:ainstructionisissuedwhenThefunctionalunitisavailableandNootheractiveinstructionhasthesamedestinationregister.Avo