Power-Aware Computer Systems

WelcometotheproceedingsofthePower-AwareComputerSystems(PACS2002) workshopheld in conjunction with the 8th InternationalSymposium on High PerformanceComputerArchitecture(HPCA-8). Improvementsincomputers- temperformancehavebeenaccompaniedbyanalarmingincreaseinpowerand energydissipation, leading tohigher costandlowerreliabilityinallcomputer systemsmarketsegments. Thehigherpower/energydissipationhasalsosign- icantlyreducedbatterylife inportablesystems. Whilecircuit-leveltechniques continuetoreducepowerandenergy, alllevelsofcomputersystemsarebeing usedtoaddresspowerandenergyissues. PACS2002wasthesecondworkshopin itsseriestoaddresspower-/energy-awarenessatalllevelsofcomputersystems andbroughttogetherexpertsfromacademiaandindustry. Theseproceedingsincluderesearchpapersspanningawidespectrumof- eas in power-aware systems. We have grouped the papers into the following categories: (1)power-awarearchitectureandmicroarchitecture, (2)power-aware real-time systems, (3) power modeling and monitoring, and (4) power-aware operatingsystemsandcompilers. The?rstgroupofpapersproposepower-awaretechniquesfortheprocessor pipeline using adaptiveresizing of power-hungrymicroarchitecturalstructures andclockgating, andpower-awarecachedesignbyavoidingtagchecksin- riodswhenthetagshavenotchanged. Thisgroupalsoincludesideastoadapt energyandperformancedynamicallybydetectingregionsofapplicationatr- timewherethesupplyvoltagemaybescaledtoreducepowerwithabounded decrease in performance. Lastly, a paper on multiprocessor designs trades o? computingcapacityandfunctionalityforimprovedenergypercyclebysched- ing simple tasks on low-end and low-energy processorsand complex tasks on high-endprocessors. Thesecondgroupofpaperstargetreal-timesystemsincludingideasonal- complexityheuristicwhichschedulesreal-timetaskssuchthatnotaskmissesits deadlineandthetotalenergysavingsaremaximized. Theotherpapersinthis group(1)tunethesystem-levelparallelismtothecurrent-levelofpower/energy availabilityandoptimizethesystempowerutilization, and(2)performadaptive texturemappinginreal-time3Dgraphicssystemsbasedonamodelofhuman visualperceptiontoachievesigni?cantpowersavingswithoutnoticeableimage qualitydegradation. Thethirdgroupofpapersfocusonpowermodelingandmonitoringincluding statisticalpro?lingtodetectsoftwarehotspotsofpower, andusingPetriNetsto modelDRAMpowerpolicies. Thisgroupalsoincludesasimulatorforevaluating theperformanceandpowerofdynamicvoltagescalingalgorithms. Thelast groupconcentratesonOS and compilersfor lowpower. The ?rst paperproposesapplication-issueddirectivestosetthepowermodesindevices suchasadiskdrive. Thesecondpaperproposespoliciesforcluster-widepower VI Preface management. Thepoliciesemploycombinationsofdynamicvoltagescalingand turningonando?toreduceoverallclusterpower. PACS2002wasahighlysuccessfulforumduetothehigh-qualitysubmissions, theenormouse?ortsoftheprogramcommitteeandthekeynotespeaker, andthe attendees. WewouldliketothankRonnyRonenforanexcellentkeynotespeech, showingthetechnologicalscalingtrendsandtheirimpactonenergy/powerc- sumption in general-purposemicroprocessors, and pinpointing recentmicro- chitecturalstrategiestoachievemorepower-e?cientmicroprocessors. Wewould like to also thank Antonio Gonzalez, Andreas Moshovos, John Kalamatianos, andothermembersoftheHPCA-8organizingcommitteewhohelpedarrange forlocalaccomodationandpublicizetheworkshop. February2002 BabakFalsa?andT. N. Vijaykumar PACS2002 Program Committee BabakFalsa?, CarnegieMellonUniversity(co-chair) T. N. Vijaykumar, PurdueUniversity(co-chair) DaveA