Principles of Computer Design

Principles of Computer Design - 02-1 02-1...

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Unformatted text preview: 02-1 02-1 QuantitativeComputerDesign Designguidedbymeasuredperformance. Covered: DesignPrinciples(1.6) ComponentsofCPUPerformance(QuantitativePrinciples)(1.6) Benchmarks(1.5) (Numbersrefertobooksections.) 02-1 EE4720LectureTransparency.Formatted10:24,28August2002fromlsli02. 02-1 02-2 02-2 PrinciplesofComputerDesign Principlescomputerdesignersapplywidely. Makethecommoncasefast. Obviously. (Notcovered.) AmdahlsLaw: Dontmakecommoncasetoofast. Asspeedofonepartincreases ... ... impactontotalperformancedrops. (Notcovered.) LocalityofReference. Temporal: Itmighthappenagainsoon. Spatial: Itmighthappentoyourneighborssoontoo. 02-2 EE4720LectureTransparency.Formatted10:24,28August2002fromlsli02. 02-2 02-3 02-3 Locality Thefirsttwoprinciplesarecommonsense. However,localityisacharacteristic ofexecutingprograms ... ... whichhasheldandisexpectedtocontinuetohold. Becausemanydesignsworkonlywhenlocalityispresent ... ... ifitallofasuddenprogramsdidnotexhibitlocality ... ... computerswouldrunthemmany,manytimesslower! Localityusuallyappliedtomemoryaddressesissuedbyprocessor. Temporal: theresagoodchancethatanaddressusedwillbeusedagainsoon. Spatial: onceanaddressisusedtheresagoodchanceanearbyaddresswillbeused. Forexamples,analyzeexecutionofalmostanyprogram. 02-3 EE4720LectureTransparency.Formatted10:24,28August2002fromlsli02. 02-3 02-4 02-4 ComponentsofCPUPerformanceandPerformanceEquation CPUPerformanceDecomposedintoThreeComponents: ClockFrequency( ) Determinedbytechnologyandinfluencedbyorganization. ClocksperInstruction(CPI) Determinedbyorganizationandinstructionmix. InstructionCount(IC) DeterminedbyprogramandISA. Thesecombinedtoform CPUPerformanceEquation t T = 1 CPI IC , where t T denotestheexecutiontime. 02-4 EE4720LectureTransparency.Formatted10:24,28August2002fromlsli02. 02-4 02-5 02-5 ComponentofCPUPerformance:InstructionCount Givenaprogramtherearetwowaysinstructionscouldbetallied: StaticInstructionCount: Thenumberofinstructionsmakinguptheprogram. DynamicInstructionCount(IC): Thenumberofinstructionsexecutedinarunoftheprogram. Forestimatingperformance,dynamicinstructioncountisused. 02-5 EE4720LectureTransparency.Formatted10:24,28August2002fromlsli02. 02-5 02-6 02-6 InstructionCounts Example,assemblerprogramthatcomputes a = 9 i =0 i . WritteninSimplescalarassembler. IC 1 move r5,r0 !r0isalwayszero. 1 move r3,r0 L23: !Branchlabel. 10 addu r5,r5,r3 !Addunsigned. 10 addu r3,r3,1 10 slt r2,r3,10 !r2=r3<10 10 bne r2,r0,L23!BranchtoL23ifr2notequal0. Staticcount:6(numberofinstructions). Dynamiccount:42. 02-6 EE4720LectureTransparency.Formatted10:24,28August2002fromlsli02. 02-6 02-7 02-7 ComponentofCPUPerformance:ClockFrequency CPUsimplementedusingsynchronousclockedlogic. TypicalClockCycle Whenclockswitchesfromlowtohighworkstarts. Whileclockishighworkproceeds. Whenclockgoesfromhightolowworkshouldbecomplete. Clockfrequencydeterminedby criticalpath . CriticalPath: Logicdoingmosttimeconsumingwork(inacycle).Logicdoingmosttimeconsumingwork(inacycle)....
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