现代计算机体系结构.ppt

现代计算机体系结构1现代计算机体系结构主讲教师：张钢教授天津大学计算机学院通信邮箱：提交作业邮箱：2016年

2TheMainContents课程主要内容Chapter1.FundamentalsofQuantitativeDesignandAnalysisChapter2.MemoryHierarchyDesignChapter3.Instruction-LevelParallelismandItsExploitationChapter4.Data-LevelParallelisminVector,SIMD,andGPUArchitecturesChapter5.Thread-LevelParallelismChapter6.Warehouse-ScaleComputerstoExploitRequest-LevelandData-LevelParallelismAppendixA.Pipelining:BasicandIntermediateConcepts

3.4/3.5/3.6课堂讨论

AdvantagesofDynamicSchedulingDynamicschedulingHardwarerearrangestheinstructionexecutiontoreducestallswhilemaintainingdataflowandexceptionbehaviorWhat’sthemeaningthatmaintainingdataflowandexceptionbehavior?

AdvantagesofDynamicSchedulingAdvantagesIthandlescaseswhendependencesunknownatcompiletimeitallowstheprocessortotolerateunpredictabledelayssuchascachemisses,byexecutingothercodewhilewaitingforthemisstoresolveItallowscodethatcompiledforonepipelinetorunefficientlyonadifferentpipelineItsimplifiesthecompilerWhy?

HWSchemes:InstructionParallelismKeyidea:Allowinstructionsbehindstalltoproceed

DIVD F0,F2,F4

ADDD F10,F0,F8

SUBD F12,F8,F14Enablesout-of-orderexecutionandallowsout-of-ordercompletion(e.g.,SUBD)Inadynamicallyscheduledpipeline,allinstructionsstillpassthroughissuestageinorder(in-orderissue)Whatarethemeaningthatin-orderissue,out-of-orderexecution,out-of-ordercompletion?

HWSchemes:InstructionParallelisilldistinguishwhenaninstructionbeginsexecutionandwhenitcompletesexecution;between2times,theinstructionisinexecutionWhenandWhereinapipeline?Note:DynamicexecutioncreatesWARandWAWhazardsandmakesexceptionsharderWhyitcancreateWARandWAW?

DynamicSchedulingStep1Simplepipelinehad1stagetocheckbothstructuralanddatahazards:InstructionDecode(ID),alsocalledInstructionIssueSplittheIDpipestage