e €redi™tive ƒystem ƒhutdown wetho d for inergy ƒ—ving of

iventEhriven gomput—tion

ghiErong rw—ng —nd ellen gFErF ‡u

hep—rtment of gomputer ƒ™ien™eD „sing ru— niversity

rsin™huD „—iw—nD QHHD ‚epu˜li™ of ghin—

f™hungh—wd™sFnthuFeduFtwg

e˜str—™t sn — re™ent studyD ƒriv—st—v— et —lF ‘U“ ™ondu™ted

—n extensive —n—lysis on dierent systemEshutdown —pE

„his p—per presents — systemElevel power m—n—gement

pro—™hesF „heir s—mple tr—™es on —n ˆEserverD —n eventE

te™hnique for power s—ving of eventEdriven —ppli™—tionsF

driven —ppli™—tionD showed th—t it sp ends over WH7 of its

‡e present — new predi™tive systemEshutdown methodto

time in the ˜lo ™ked st—te —nd the —ver—ge time visiting

exploit sleep mode oper—tions for power s—vingF ‡e use

the ˜lo ™ked st—te is less th—n one se™ondF es — resultD

—n exponenti—lE—ver—ge —ppro—™h to predi™t the up™oming

the ™onvention—l —ppro—™h will f—il to ee™tively —™hieve

id le periodF ‡e introdu™e two me™h—nismsD predi™tionE

power redu™tion on this typ e of —ppli™—tionF „hey h—ve

miss ™orre™tion —nd preEw—keupD to improve the hit r—tio

prop osed — predi™tive systemEshutdown te™hnique for enE

—nd to redu™e the del—y overhe—dF ixperiments on four

ergy s—ving of eventEdriven —ppli™—tionsF „hey rst ™olE

dierent eventEdriven —ppli™—tions show th—t our proE

le™ted s—mple tr—™es of onEo —™tivity on —n ˆEserverF

posed method —™hieves high hit r—tios in — wide r—nge of

„henD they prop osed two predi™tive formul—s ˜—sed on

del—y overhe—dsD whi™h results in — high degreeofpower

the —n—lysis of the s—mple tr—™esF „he rst formul— w—s

s—ving with low del—y pen—ltiesF

o˜t—ined ˜y using — gener—l regressionE—n—lysis te™hnique

I sntro du™tion

to ™orrel—te the length of the up ™oming o p erio d to the

‡ith the —dvent of p ort—˜le ™omputing —nd high denE

lengths of the previous on —nd o p erio dsF „he se™ond

sity †vƒs ™ir™uitsD p ower dissip—tion h—s emerged —s —

formul— w—s o˜t—ined ˜y the o˜serv—tion of the onEo —™E

prin™iple design ™onsider—tion in †vƒs designsF sn the

tivity ˜ eh—viorF „hey o˜served th—t ’the idle p erio d folE

p—st few ye—rsD — h—ndful of p ower estim—tion —nd miniE

lowing — long running p erio d tends to ˜ e short4F f—sed

miz—tion metho ds h—ve ˜ een rep orted for —™hieving low

on this o˜serv—tionD they derived — formul— whi™h lters

power designs —t ™ir™uitD l—youtD logi™D ˜ eh—vior—lD —nd

out the idle p erio d fullling the —˜ ove ™ondition —nd the

—r™hite™tur—l levelsF ƒever—l ex™ellent reviews of p ower

system enters the sleep st—te otherwiseF f—sed on the

estim—tion —nd minimiz—tion te™hniques —re given ˜y€eE

two formul—sD they ™ondu™ted — series of exp eriments on

dr—m ‘I“D hev—d—s —nd w—lik ‘P“D —nd x— jm ‘QD R“F

—n ˆ ™lient —ppli™—tionF „he results demonstr—ted th—t

vowpower †vƒs designs ™—n ˜ e —™hieved —t v—riE

predi™tiveshutdown te™hniques ™—n redu™e the p ower

ous design levelsF sn this studyDwe fo ™us on utilizing

™onsumption ˜y — l—rge f—™tor ™omp—red to the ™onvenE

— predi™tive systemEshutdown te™hnique for p ower s—vE

tion—l metho dF roweverD one dr—w˜—™k of this —ppro—™h

ing of eventEdriven —ppli™—tionsF €ower m—n—gement

is th—t the predi™tive formul— is dire™tly derived from

te™hniques h—ve ˜ een extensively —pplied to €g systemsF

the s—mple tr—™es of — sp e™i™ —ppli™—tionF por dierent

por inst—n™eD the design of the €ower€gTHQ ‘S“ —pplied

—ppli™—tionsD dierent predi™tive formul—s —re needed in

twotyp es of p ower m—n—gements™hemesX st—ti™ —nd dyE

order to m—ke —™™ur—te predi™tionsF

n—mi™F sn st—ti™ p ower m—n—gementD the system denes

sn this p—p erD we present — new predi™tive systemE

sever—l sleep mo des with v—rious levels of p ower s—ving

shutdown metho d for eventEdriven —ppli™—tionsF ‡e use

—nd del—yoverhe—d whi™h ™—n ˜ e ™ontrolled extern—lly

—wellEknown exp onenti—lE—ver—ge —ppro—™h to predi™t

˜y softw—reF sn dyn—mi™ p ower m—n—gementD the system

the up ™oming idle p erio dF ‡eintro du™e two me™h—E

will —utom—ti™—lly dete™t the idle p erio ds —nd dis—˜le the

nismsD predi™tionEmiss ™orre™tion —nd preEw—keupD to imE

™lo ™ks on p ortions of the g€ F epple9s w—™ €owerfo oks

prove the hit r—tio —nd to redu™e the del—yoverhe—dF

‘T“ use — dierent —ppro—™h whi™henters rest mo de —fter

ixp eriments on four dierenteventEdriven —ppli™—tions

P se™onds of idle timeF huring rest mo deD the pro ™essor

—re rep orted to demonstr—te the ee™tiveness of our proE

is p owered down ˜ut the sGy devi™es rem—in onF „ypiE

p osed metho dF

™—llyD ™onvention—l shutdown —ppro—™hes —re ™—rried out

˜—sed on the rule of go to sleep —fter the system h—s ˜een

P „he prop osed metho d

id le for — predenedperiod of timeFroweverD this —pE

PFI inergy s—ving using — systemEshutdown

pro—™h p oses —n o˜vious dr—w˜—™k E the system ™ontinues

te™hnique

to ™onsume p ower in th—t interv—l of idle timeF

pigure I depi™ts — simple shutdown —ppro—™h for

y

eventEdriven —ppli™—tionsF ‡hen the system dete™ts —n

„his work w—s supp orted in p—rt ˜y the x—tion—l ƒ™ien™e

idle p erio dD it will determine whether it should st—yin

goun™il of ‚FyFgF under qr—nt xƒg VSEPPPIEiEHHUEHQR —nd xƒg

the running st—te or enter the sleep st—teF sf the system VTEPPPIEiEHHUEHPIF

0-89791-993-9/97 $10.00  1997 IEEE

! iY @IA Wake−up s

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RESWR R EW R ‚

ve deriv—tions indi™—te th—t iqnsF I —nd U —re

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the ne™ess—ry ™onditions under whi™h the idle p erio d will

pigure PX„wo p ossi˜le s™en—rios when —pplying — simple

—™hieve energy s—vingsF ‡e dene ƒ —s the threshold

th

systemEshutdown s™hemeX@—A s ! i D@˜A s i F

idle p erio d th—t results in energy s—ving of the systemF

de™ides to enter the sleep st—teD the system rst p erforms

PFP €redi™tion of idle p erio ds

—num˜ er of housekeeping pro ™eduresD su™h —s ˜—™kingE

„he —n—lysis in the previous se™tion indi™—tes th—t

up d—t— —nd system st—tusF „he system then st—ys in

predi™ting the idle p erio d s is vit—l for —n ee™tivepower

the energyEs—ving sleep st—te until —n extern—l w—keup

m—n—gement me™h—nismF roweverD the distri˜ution —nd

sign—l o ™™ursF ‡hen — w—keup sign—l o ™™ursD the system

v—ri—tion of s m—y ˜ e strongly dep endent on the user ˜ eE

will p erform re™overy pro ™eduresD su™h —s d—t— restoringD

h—viorD t—rget —ppli™—tionsD working frequen™yD —nd opE

—nd then resume the running st—teF sf the de™ision is not

er—ting systemF

to enter the sleep st—teD the system st—ys in the running

sn our —ppro—™hD we —d—pt the exponenti—lE—ver—ge

st—te —s ˜usy w—itingF yne of the ™ru™i—l issues of this

—ppro—™h‘V“ used in the g€ s™heduling pro˜lem for

—ppro—™his’whether or not to shutdown the systemD —nd

the predi™tion of the idle p erio dF sn the g€ s™heduling

if so whenc4 so th—t p ower dissip—tion of the system ™—n

pro˜lemD op er—ting systems need to predi™t the length of

˜ e redu™edF „his issue will ˜ e dis™ussed —s followsF

the next g€ ˜urst in order to m—ke —ppropri—te pro ™ess

vet s ˜ e the idle time p erio dD i the del—yoverhe—d

s™hedulingF sn gener—lD the next g€ ˜urst is predi™ted

of entering the sleep st—te from the running st—teD ƒ the

—s —n —™™umul—tive—ver—ge of the me—sured lengths of

sleeping time p erio dD —nd ‡ the del—yoverhe—d for reE

previous g€ ˜urstsF ƒimil—rlyDwe ™—n predi™t the next

suming the running st—te from the sleep st—te @the w—ke

idle p erio d ˜y the —™™umul—tive—ver—ge of the previous

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idle p erio dsF „he re™ursive predi™tion formul— is shown

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ues of the system in the running —nd sleep st—tesD resp e™E

˜ elowF

tivelyF € is the —ver—ge p owerEdissip—tion overhe—d

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s a —
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of entering the sleep st—te from the running st—te —nd

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™—llyD € ! € ! € F pin—llyD iq denotes the energy

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g—in of the systemF

™onst—nt —ttenu—tion f—™tor in the r—nge ˜ etween H to

IF sn this formul—D s is the inerti— —nd i is the for™e

n n

essume th—t the system will enter the sleep st—te

to push the predi™ted idle p erio d tow—rd the —™tu—l idle

whenever it dete™ts —n idle p erio dF pigure P@—A shows

p erio dF ‡e ™—n use iqnF V to predi™t the up ™oming idle

the rst s™en—rio in whi™h the idle p erio d is longer th—n

p erio dD whi™h is — fun™tion of the l—test idle p erio d —nd

the del—yoverhe—d of entering the sleep st—te from the

the previous predi™ted v—lueF „he p—r—meter — ™ontrols

running st—te @iFeFD s ! i AF ƒin™e s ! i D the system will

the rel—tiveweight of re™ent —nd p—st history in the preE

su™™essfully enter the sleep st—te —nd resume the running

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then s a i F sn this ™—seD the predi™tion only t—kes

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into —™™ount the most re™ent idle p erio d ˜ut ignores the

ond s™en—rio in whi™h the idle p erio d is shorter th—n the

previous predi™tionsF sn our implement—tionD — is set to

del—yoverhe—d of entering the sleep st—te from the runE

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ning st—te @iFeFD s i AF sn this ™—seD the system will

equ—lly weightedF ‡e ™—n exp—nd iqnF V —s ˜ elowF

never enter the sleep st—te —nd will suer — long del—y

p en—lty@del —y a ‡ C@i sAA —nd — neg—tive energy

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iqnF W indi™—tes th—t the predi™ted idle p erio d is the

the running st—te @iFeFD s ! i AF

weighted —ver—ge of previous idle p erio dsF i—rly idle

vet us further —n—lyze the minimum required idle p eE p erio ds h—ve less weight —s sp e™ied ˜y the exp onenti—l

rio d for —™hieving — p ositive energy g—in —s followsF —ttenu—tion f—™torsF I1R1 I2 R2 I3 R3 I4 R4 RIR RIR

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™ondition to iqnF V —s ˜ elowF

pigure QX gorre™tion of predi™tion missX @—A —n impulseEli ke

idle p erio dD @˜A ™orre™tion using — w—t™hdog s™hemeF

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the growing r—te of s is limited to ™ times p er up d—teF

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ren™e of impulseElike idle p erio ds E — suddenD very long

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tem resumes the running st—te from the sleep st—te @iFeFD

pigure Q@—AF por ex—mpleD the user works on the system

system w—keEupAD the system needs to p erform some reE

for — while —nd then go es to —nswer — telephone resulting

™overy pro ™eduresF sn other wordsD the system suers

in the system idling for — long p erio d of timeF ‡hen su™h

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—n impulseElike idle p erio d o ™™ursD the predi™tion of the

„his del—y p en—ltym—yh—ve — gre—t imp—™t on system

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resp onsiveness in some ™—sesD esp e™i—lly when ‡ is to o

˜ e —™™ur—teF „he re—sons —re dis™ussed —s followsF ‚e™—ll

long to ˜ e negle™tedF yne w—y to resolve this pro˜lem is

th—t our prop osed predi™tion formul— @iqnF VA predi™ts

to preEw—keup the system ˜ efore the —rriv—l of the next

the up ™oming idle p erio d ˜y the —™™umul—tive—ver—ge of

w—keup sign—lF „his ™—n ˜ e —™™omplished ˜y predi™ting

the previous idle p erio dsF ‡hen — very long idle p erio d

the o ™™urren™e of the next w—keup sign—lF

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o ™™urs —fter ™ontinuousD ne—rly uniform idle p erio dsD the

vet s ˜ e the —™tu—l idle p erio dD s the predi™ted idle

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predi™ted v—lue of this long idle p erio d is often mu™h

p erio dD —nd h a js s j the error of the predi™tionF pigE

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lower th—n the —™tu—l idle p erio d @s Q bsQAF „his unE

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when the predi™ted v—lue is lower th—n ƒ F sn this ™—seD

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m—te the predi™ted idle p erio d ˜y h @iFeFD s bsA —nd

the system will st—y in the running st—te inste—d of enE

h ‡ F sn this ™—seD the system will w—keup ‡ h

tering the sleep st—te whi™h results in — l—rge —mount

time —he—d of the next w—keup sign—lD —s shown in pigE

of unne™ess—ry p ower ™onsumptionF yn the other h—ndD

ure R@—AF „husD the del—y p en—ltyish whi™h is shorter

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ergy g—in is iq a s
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—lso undesir—˜le ˜ e™—use the system m—y f—lsely enter the

the system will ˜ e woken up ˜y the origin—l w—keup sigE

sleep st—te —nd suers unne™ess—ry p ower ™onsumption

n—lF sn this ™—seD the preEw—keup h—s no ee™t on the

—nd del—ysF

redu™tion of the del—y p en—ltyF pigure R@˜A shows the

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„o —llevi—te the rst pro˜lemD we use — w—t™hdog

se™ond s™en—rio in whi™h s `sF sn this ™—seD the deE

s™heme to p erio di™—lly monitor the ™urrent idle p erio dF

l—y p en—lty is zero ˜ut the energy g—in is redu™ed to

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th—n the —™tu—l idle p erio dD there will ˜ e no resp onsiveE

st—rts up — timer to tr—™e the —™tu—l idle p erio dF „he

ness del—yFroweverD the energy s—ving will not ˜ e —s

system then p erforms — new predi™tion every ƒ time

th

ee™tive —s the origin—l oneF

to determine whether the system should enter the sleep

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st—teF por ex—mpleD in pigure Q@˜AD ˜y the end of runE

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th

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predi™tion —g—inD resulting in s Q F sf the predi™ted v—lue st—teF ‡hen —n idle p erio d o ™™ursD the system predi™ts

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tors the timer —nd enters the ™orre™t st—te every ƒ of

th (b) Netscape (d) Telnet

timeF sn the ™orre™t st—teD the system reEpredi™ts the pigure TX gomp—risons of hit r—tiosF

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st—teF sn the sleep st—teD the system will return to the

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s

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energy s—ving is the r—tio ˜ etween the tot—l p ower disE

will return to the running st—te either when — w—keup

sip—tion ˜ efore —nd —fter —pplying the systemEshutdown

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—ppli™—tionsX @IA ˆEserverD @PA xets™—p eD @QA telnetD —nd

€
„

‚ t

% Y @ITA

H

@RA tinF „he exp eriments were ™ondu™ted on — ƒ€e‚gIH

„ @€ HXHS
€ A €
„

s ‚ ‚ ‚

t

workst—tion running the ƒunyƒ RFIFQ op er—ting systemF

„

t

sn our implement—tionD we set the ™onst—nts — a

a X @IUA

H

HXWS„ „

s

t

HFS @iqnF VA —nd ™ a P @iqnF IHAF ‡e —ssume

I

i a ‡ a „ D where „ is the del—yoverhe—dF

™ost ™ost

P

sn the rst exp erimentD we tested the hit r—tio of our

pirstD we determine the threshold idle p erio d ƒ @iqnF

th

prop osed metho dF ‡e dene — hit in twow—ysX @IA the

UAF ‚e™—ll th—t

system enters the sleep st—te —nd results in p ower s—ving

or @PA the system do es not enter the sleep st—te if it will

i
@€ € AC ‡
€

i‡ ƒ i‡

ƒ ! X @IIA

not result in p ower s—vingF pigures T@—AD @˜AD @™AD —nd @dA

th

@€ € A

‚ ƒ

show the hit r—tios of the four —ppli™—tions ˆEserverD

xets™—p eD „inD —nd „elnetD resp e™tivelyF „ is the deE

‡e —ssume th—t the —ver—ge p ower dissip—tion of enE

™ost

l—y p en—lty for shutting down the systemF ‡eh—ve ™omE

tering —nd resuming from the sleep st—te € is s—me —s

i‡

p—red the hit r—tios using three predi™tive metho dsX @IA

the p ower ™onsumed in the running st—teY iFeFD € a

i‡

on thr eshol d@IA ˜—sed ‘U“D @PA our prop osed metho d

€ F sn —dditionD —™™ording to the d—t— sheet of the €owE

‚

without miss ™orre™tionD —nd @QA the prop osed metho d

er€g ‘S“D we dene the p ower dissip—tion in the sleep

with miss ™orre™tionF „he results show th—t when the

st—te to ˜ e —pproxim—tely S7 of the p ower dissip—tion

„ is low @eFgFDHFHHI se™ond for „inD HFHI se™ond for the

in the running st—teY iFeFD € aHXHS
€ F ren™eD

™ost

ƒ ‚

ˆEserver —nd xets™—p eD —nd HFI se™ond for „elnetAD ˜ oth

the on thr eshol d@IA ˜—sed —nd our metho d pro du™ed

IaP
„
@€ HXHS
€ ACIaP
„
€

™ost ‚ ‚ ™ost ‚

the s—me hit r—tioF ‡hen the „ in™re—sesD the hit

™ost

ƒ % @IPA

th

@€ HXHS
€ A

‚ ‚

r—tio of the on thr eshol d@IA ˜—sed metho d de™re—ses

r—pidlyF sn ™ontr—stD our prop osed metho d ™onsistently

HXS  IXWS

a
„ aIXHPT
„ X @IQA

™ost ™ost

gives high hit r—tiosF „he results —lso show th—t the ™orE

HXWS

re™tion metho d improves the hit r—tio ˜y—n—ver—ge of

PH7 ™omp—red to th—t without —pplying the ™orre™tion e re—son—˜le v—lue of ƒ is l—rger th—n IXHPT
„ F

th ™ost

metho dF sn our implement—tionD we set ƒ aIXS
„ F

th ™ost

sn the se™ond exp erimentD we ™omp—red the energy ‡e —lso dene two qu—lity me—suresX hel—yEyverhe—d

s—ving —nd del—yoverhe—d using ve systemEshutdown @hyA —nd inergyEƒ—ving @iƒAF hel—yoverhe—d is the

metho dsX @IA €w D @PA €w D @QA €w D @RA r—tio ˜ etween the tot—l el—psed time —fter —pplying the

Pse™ „hˆ „hI

H

€w D —nd @SA €w F „he rst one is — metho d used in systemEshutdown s™heme @„ A —nd the origin—l el—psed

s ss

t

the epple €g system ‘T“ in whi™h the system will enter time @„ A—s t

R gon™lusions

sn this p—p erD weh—ve presented — predi™tiveshutE

„ €w €w €w €w €w

™ost

Pse™ s ss

„hˆ „hsnf

down metho d for eventEdriven ™omput—tionF ‡eh—ve

ˆEserver@hel—yEyverhe—d@7AGinergyEƒ—vingA

H HGQFUS HGITFV HGIVFUQ HGIVFUH HGIVFUH

™ondu™ted exp eriments on four eventEdriven —ppli™—tions

Ims HGQFUS FHQGITFTQ FHQGIVFSQ FHQGIVFSH FHQGIUFWW

IHms FHPGQFUS FQGISFPW FQGITFVU FHQGITFVH FHPWGIQFUH

—nd ™omp—red our —ppro—™htotwo other system shutE

HFIs FPRGQFTV QFPVGVFRS QFQGVFVW PFIVGVFQV IFUGSFIR

down metho dsF „he results h—ve shown th—t when the

Is PFSVGQFIV IUGIFIR RVGIFSQ VFQGQFPW IFVGIFWP

shutdown overhe—d is high @eFgFD „ ! I se™ondAD the

xets™—p e@hel—yEyverhe—d@7AGinergyEƒ—vingA

™ost

H HGIFTH HGRFUU HGVFWP HGVFVP HGVFVP

™onvention—l metho dD su™h —s th—t used ˜y the epple

Ims HGIFTH FIIGRFUP FIPGVFUQ FIPGVFTQ FIIGVFIQ

€ower€gD ™—n —™hieve — re—son—˜le p ower s—vingF rowE

IHms FHUGIFTH IFQQGRFPW IFQVGUFQR IFIRGUFIV FWUGSFPV

HFIs FUQGIFST ITFVGPFPT IUFRGPFVP PFTQGQFTQ IFVGPFIH

everD this metho d do es not —™hieve —n ee™tivepower

Is VFIIGIFQH IQFQRGHFVV QPIGHFQW IHFRRGIFQU FVUGIFHT

s—ving when the shutdown overhe—d is low @eFgFD „ `

™ost

„in@hel—yEyverhe—d@7AGinergyEƒ—vingA

H HGPFVT HGITFQP HGITFQQ HGITFQQ HGITFQQ

I se™ondAF yn the other h—ndD when the shutdown overE

Ims HGPFVT FHTGITFHP FHTGITFHQ FHTGITFHP FHSGISFHR

he—d is low @eFgFD „ ` I se™ondAD — more —ggressive

IHms FHQGPFVS FUQGIQFUH FUQGIQFUI FRUGIQFTT FQVGWFWP

™ost

HFIs FQSGPFVH WFRVGSFSW WFSGSFSV IFUIGUFRQ IFQPGQFUR

predi™tiveshutdown metho d ‘U“ ™—n —™hieve — higher

Is QFWWGPFQV QFSTGHFWU PHUGHFVH SFUUGPFUI FWPGIFSR

degree of p ower s—ving ™omp—red to the ™onvention—l

„elnet@hel—yEyverhe—d@7AGinergyEƒ—vingA

H HGPFTQ HGIVFIV HGIWFIW HGISFIS HGISFIS

metho dF roweverD this metho d do es not p erform well

Ims HGPFTQ FHIGIVFHV FHIGIWFHW FHIGISFHV FHIGIRFWT

when the shutdown overhe—d is highF sn —dditionD ˜ eE

IHms FHSGPFTP FIQGIUFQP FIQGIVFPQ FIQGIRFSR FIQGIQFRW

HFIs FSUGPFSS IFRQGIPFIT IFRQGIPFTH IFRPGIHFUP IFQRGUFII

™—use the predi™tive formul— of this —ppro—™h h—s to deE

Is TFHRGPFHR UFHPGIFIU ISFWWGQFHU IIFQIGPFRT VFSRGIFUW

rived dire™tly from the s—mple tr—™es of the t—rget —pE

pli™—tionD weh—ve to —n—lyze the s—mple tr—™es for e—™h

„—˜le IX gomp—risons of v—rious system shutdown metho dsF

—ppli™—tion in order to determine the threshold v—lueF

yn the other h—ndD our prop osed metho d dep ends solely

the sleep st—te whenever — PEse™ond idle p erio d is deE

on the history of the previous idle p erio ds —nd the p ower

te™tedF „he se™ond —nd third metho ds were prop osed

dissip—tion of the t—rget system @eFgFD the —ver—ge p ower

˜y ƒriv—st—v— etF —lF ‘U“F „o determine — re—son—˜le

™onsumption in the sleep —nd running st—tesAD whi™his

threshold v—lue for the se™ond metho dD we rst —n—lyzed

indep endent of the t—rget —ppli™—tionsF purthermoreD the

the rel—tionship ˜ etween onEo p erio ds of the s—mple

results h—ve shown th—t our prop osed metho d —™hieves

tr—™esF „he results show th—t we o˜t—ined the simil—r vE

high hit r—tios for — wide r—nge of shutdown overhe—dsD

sh—p ed onEo p erio ds rel—tionship —s o˜served in ‘U“ for

whi™h results in — high degree of p ower s—ving with low

the four —ppli™—tionsF prom the o˜serv—tionsD we set the

del—y p en—ltiesF

„ v—lue to SHms for „ in the r—nge of HEHFI

thr eshold ™ost

gurrentlyD our prop osed metho d fo ™uses on — single

se™ond —nd Pms for „ of I se™ondD IHHms for „ aHE

™ost ™ost

sleep mo deF roweverD m—ny pro ™essors provide — v—riety

HFI se™ond —nd Ims for „ a I se™ondD PHHms for „

™ost ™ost

of sleep mo des with dierent levels of p ower s—ving —nd

a HEHFI se™ond —nd Ims for „ a I se™ondD —nd RHms

™ost

shutdown overhe—dF puture work will extend our metho d

for „ a HEHFI se™ond —nd Rms for „ a I se™ondD

™ost ™ost

to —™™omo d—te multiElevel sleep mo desF

for the ˆEserverD xets™—p eD „inD —nd „elnetD resp e™tivelyF

„he fourth metho d is our prop osed metho d without —pE

‚eferen™es

plying the preEw—keup s™hemeF „he n—l metho d is our

‘I“ wF €edr—mD ’€ower winimiz—tion in sg hesignX €rin™iples —nd

eppli™—tionsD4 egw „r—nsF on hesign eutom—tion of ile™troni™

prop osed metho d in™luding the preEw—keup s™hemeF

ƒystemsDvolF ID noF ID ppFQESTD t—nu—ryD IWWTF

‘P“ ƒF hev—d—s —nd ƒF w—likD ’e ƒurvey of yptimiz—tion „e™hniques

„—˜le I shows the resultsF prom the resultsD the folE

„—rgeting vow€ower †vƒs gir™uitsD4 in €ro™F of the QPnd hesign

eutom—tion gonfFD ppF PRPEPRUD IWWSF

lowing o˜serv—tions ™—n ˜ e m—deF pirstD the €w

Pse™

metho d p erforms well when „ aIs ˜ut p o orly when

™ost

‘Q“ pF xF x— jmD ’e ƒurvey of €ower istim—tion „e™hniques in †vƒs

„ is in the r—nge of H to HFI se™ondF ƒe™ondD when

™ost

gir™uitsD4 siii „r—nsF on †vƒs ƒystemsDvolF PD noF RD ppFRRTERSSD

„ is in the r—nge of H to HFI se™ondD the €w

he™em˜ er IWWRF

™ost „hI

—™hieves the ˜ est p ower s—vingF roweverD when „ a

™ost

‘R“ pF xF x— jmD ’€ower istim—tion „e™hniques for sntegr—ted girE

ID p ower s—ving drops sh—rply —nd del—yoverhe—d inE

™uitsD4 in €ro™F of the sggehD ppF RWPERWWD IWWSF

™re—ses r—pidlyFpor ex—mpleD for the ˆEserver —ppli™—E

tionD it o˜t—ins IFSQ times p ower s—ving with RV7 del—y

‘S“ ƒF q—ryD’€ower€gX e wi™ropro ™essor for €ort—˜le gomputersD4

siii hesign of gomputersD ppF IREPQD ‡inter IWWRF

overhe—dF por the xets™—p e —nd „in —ppli™—tionsD it —™E

tu—lly ™onsumes more p ower @TH7 —nd PH7 resp e™tivelyA

‘T“ epple gomputer sn™FD ’€ower w—n—ger sg —nd ‚edu™ed €ower

—nd the del—y —lso in™re—ses ˜y P to Q timesF „his is due

wo desD4 in „e™hni™—l sntrodu™tion to the w—™intosh p—milyD ‚e—dE

to the p ower —nd del—yoverhe—d ™—used ˜y the l—rge

ingD weX eddisonE‡esleyD y™tF IWWPF

num˜ er of hit missesF ƒimil—rlyD the €w metho d

„hx

‘U“ wF fF ƒriv—st—v—D eF €F gh—ndr—k—s—nD —nd ‚F ‡F fro dersonD ’€reE

p erforms well when „ is in the r—nge of H to HFI se™E

™ost

di™tive ƒystem ƒhutdown —nd yther er™hite™tur—l „e™hniques for

ond ˜ut p o orly when „ aIsF yn the other h—ndD our

™ost

inergy i™ient €rogr—mm—˜le gomput—tionD4 siii „r—nsF on

prop osed metho d €w p erforms well in the entire r—nge

†vƒs ƒystemsD ppF RPESRD volF RD noF ID w—r™h IWWTF

s

of „ a H to I se™ondF pin—llyD when —pplying the preE

™ost

‘V“ tF vF €eterson —nd eF ƒil˜ ers™h—tzD yper—ting ƒystem gon™eptsD

w—keup te™hniqueD the del—yoverhe—d ™—n ˜ e redu™ed ˜y

Pnd idFD ppF IIVEIPHD eddisonE‡esley €u˜lishing goF sn™F

s—™ri™ing some p ower s—ving @€w vFsF €w AF „his is

ss s

imp ort—nt for some timing ™riti™—l —ppli™—tionsF sn our

—ppro—™hD we —re —˜le to tr—deo del—yoverhe—d —nd

power s—ving ˜y en—˜ling —nd dis—˜ling the preEw—keup fun™tionF