FeedbackControlTheoryaComputerSystem’sPerspectiveOutlineControlOpen-loopcontrolFeedback(close-loop)ControlFeedback(close-loop)ControlWhyfeedbackcontrol?Open,unpredictableenvironmentsWhyfeedbackcontrol?WewantQoSguaranteesAdvantageoffeedbackcontroltheoryOutlineControldesignmethodologySystemModelsDynamicModelExampleUtilizationcontrolinavideoserverModelDifferentialequationThreewaysofsystemmodelingLaplacetransformofasignalf(t)BasictranslationsImpulsefunctionf(t)=(t)F(s)=1Stepsignalf(t)=a•1(t)F(s)=1/sRampsignalf(t)=a•tF(s)=a/s2Expsignalf(t)=eatF(s)=1/(s-a)Sinusoidsignalf(t)=sin(at)F(s)=a/(s2+a2)CompositionrulesLinearityL[af(t)+bg(t)]=aL[f(t)]+bL[g(t)]DifferentiationL[df(t)/dt]=sF(s)–f(0-)IntegrationL[tf()d]=F(s)/sADivergetoMathTransferfunctionADivergetoMathPolesandZerosADivergetoMathTimeresponsevs.polelocationADivergetoMathBlockdiagramBacktoOurutilizationcontrolexampleModelTransferfunc.&blockdiag.ControldesignmethodologyDesignGoalsPerformanceSpecificationsPerformanceSpecsStabilityPerformanceSpecsStabilityPerformancespecificationsExample:Control&ResponseinanEmailServer(IBM)PerformanceSpecsSteady-stateerrorPerformanceSpecsSteady-stateerrorPerformanceSpecsRobustnessPerformanceSpecsGoalofFeedbackControlControldesignmethodologyControllerDesignPIDcontrolControllerDesignCPUUtilizationControlProportionalControlStabilityProportionalControlSteady-stateerrorCPUUtilizationProportionalControlProportional-IntegralControlStabilityProportionalControlSteady-stateerrorCPUUtilizationProportional-IntegralControlControllerDesignSummary&pointersDiscreteControlDiscreteModelingRootLocusanalysisofDiscreteSystemsEffectofdiscretepolesFeedbackcontrolworksinCSAdvancedControlTopicsIssuesforComputerScienceAcknowledgements