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Energy-Efficiency in Mobile Software
JuliaRubin(jointlywithDulingLai,JürgenCito,PhillipStanley-Marbell)
January31,2017
Mobile Applications
• Morethan2billionsmartphonesinuse– Morethandesktopcomputers– Plussmartwatches,glasses,cameras,TVs,in-carnaviga=on,andmessaging
• Morethan3millionmobileappsinofficialappstores– …andmuchmoreappsinhundredsofalterna=vestores
• ~2.3millionac=vemobiledevelopersworldwide– 760,000peopleinAsia– 680,000peopleinNorthAmerica– 680,000peopleinEurope
2[h@ps://blog.newrelic.com/2014/06/13/mobile-app-development-trends-worldwide-need-know/][DeveloperEconomicsQ32014]
Mobile Application Developers
Lackknowledge,tools,andincen=vestodealwith:
– Security– Privacy– Energy-efficiency
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What Can Go Wrong?
4
What Can Go Wrong?
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Majorconsumersofenergy:Screen,WiFi,GPS,Sensors,Camera,CPU[Pathaketal.,EuroSys’12,Banerjeeetal.,FSE’14]
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Example App
GPS location used
GPS location update started
GPS location used
7
Example App
21
GPS location update started
GPS location used
8
Example App
21
GPS location update started
GPS location used
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Example App
21
1 47%moreenergy
Energy Bugs
Anerrorinthesystemthatcausesanunexpectedamountofhighenergyconsump=on
10 [Pathak et al., HotNets’11]
Energy Bugs and Hotspots
Anapplica=onconsumesanabnormallyhighamountofba^erypower…
• …evenaQerithascompletedexecuSonàBug
• …eventhoughtheu=liza=onofitshardwareresourcesislowàHotspot
11 [Banerjee et al., FSE’14]
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
12 [Banerjee et al., FSE’14]
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
13 [Banerjee et al., FSE’14]
Resources(e.g.,WiFi)thatarenotreleasedorthedevicecomponent(e.g.,screen,CPU)isleeinahigh-powerstateaeertheapplica=onhasfinishedexecu=on
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
14 [Banerjee et al., FSE’14]
Afailuretoremoveaservice(e.g.,loca=onorsensorupdates),whichwillkeeponrepor=ngdataeventhoughnoapplica=onneedsit
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
15 [Banerjee et al., FSE’14]
Respawninganapplica=onorservicewhentheapplica=onhasbeenclosedbytheuser
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
16 [Banerjee et al., FSE’14]
Bindingresourcestooearlyorreleasingthemtoolate
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
17 [Banerjee et al., FSE’14]
Sca^eredusageofcomponents(e.g.,screen,WiFi),whichcausestailenergyconsump=onwhencomponentisswitchedoff
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
18 [Banerjee et al., FSE’14]
Fine-grainedinsteadofcoarse-grainupdates(e.g.,GPSvs.WiFibasedloca=on);unnecessarilyhighsamplingrateforaservice
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
19 [Banerjee et al., FSE’14]
Repeatedlyexecu=ngpor=onoftheapplica=onevenifnotnecessary(e.g.,con=nuouslyaccessingunreachableserver)
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
20
• Pathaketal.,MobiSys’12:sta=canalysistofinddefini=ons(resourceacquisi=on)thatarenotkilled(released)
• Guoetal.,ASE’13(Relda):buildsaFunc=onCallGraph(callbacksandresource-relatedopera=ons)tocheckwhichresourcesarenotreleased
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
21
• Liuetal.,PerCom’13(GreenDroid):calculatesu=liza=onra=obyusingdynamictaintanalysis
• Banerjeeetal.,MobileSoQ’16:improvesbindingloca=onbymatchingdefectanddesignexpressions
GPS location update started
GPS location used
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Example App
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1 47%moreenergy
GPS location update started
GPS location used
23
Example App
21
1 47%moreenergy
2 visiblyslower
?
QoS Considerations
“Forbestloca=onaccuracy,youmightchoosetostartlisteningforloca=onupdateswhenusersbegincrea<ngthecontentorevenwhentheapplica<onstarts,<…>”“Youmightneedtoconsiderhowlongatypicaltaskofcrea=ngthecontenttakesandjudgeifthisdura=onallowsforefficientcollec=onofaloca=ones=mate.”
[h^ps://developer.android.com/guide/topics/loca=on/strategies.html]
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Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
25
• Chenetal.,HotPower’13:prefetchingads;upper-boundis3.2%,hardtoachieve
• Lietal.,ICSE’16:bundlessequen=alHTTPrequests,15%reduc=on
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
26
Taxonomy of Energy Bugs and Hotspots
HardwareResources
ResourceLeak
Subop=malResourceBinding
Sleep-stateTransi=onHeuris=cs
WakelockBug
TailEnergyHotspot
BackgroundServices
VacuousBackgroundServices
ExpensiveBackgroundServices
Defec=veFunc=onality
ImmortalityBug
LoopBug
27
• Citoetal.,ASE’16
Advertising and Analytics (A&A)
• Atleast3third-partylibsinanapp[Rubinatal.,ASE’15]
• Consume65%-75%ofenergy[Pathaketal.,EuroSys’12]
• Morethan40%ofHTTPconnec=onsdonotcontributetouser-observablebehavior[Rubinatal.,ASE’15]–Analy=cs
• Adver=singconsumes16%ofenergy(plus48%moreCPU=meand79%morenetworkdata)[Guietal.,ICSE’15]
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Main Idea
Automa=callyiden=fyrecurrentA&Arequestsandadapttheirfrequencytothecurrentba^erystate.
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Battery Aware Transformation Basedon• ρ–periodoftherecurrentrequests• b–ba^erystatusaddadelaybeforerecurrentA&Arequests
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Linearadapta=on:
Lowpowermode(at20%ba^erystatus):
Savings – an Example
• VLCDirect:videostreamplayer• Onerecurrentrequest–every30sec• Introduced100%delay–to60sec• Runfor30mins• 5.8%reduc=oninenergyconsump=on
(16%upperbound)
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Providing Incentives
• Problem:applica=onsare“greedy”– Donotconsiderotherapps– Donotconsiderba^erystatus
• Inplan:game-theore=calapproachformobileenergymarketplace– priceenergyandbillapplica=onsfortheenergytheyuse
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Summary
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