an analysis of power consumption in a smartphone€¦ · © nicta 2010 from imagination to impact...
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© NICTA 2010 From imagination to impact
An Analysis of Power Consumption in a
Smartphone
Aaron Carroll and Gernot Heiser
© NICTA 2010 From imagination to impact
Motivation
© NICTA 2010 From imagination to impact
Problem
• Where and how is power consumed in a smartphone?
• Approach: fine-grained instrumentation ofa real device
© NICTA 2010 From imagination to impact
Methodology
• OpenMoko Freerunner– 2.5G smartphone, c. 2008– 400 MHz ARM9– Lacking camera, 3G modem
– Open design– Amenable to power
instrumentation
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Methodology
Device
PowerManager
ADC
0 Ω100 mΩ
I = Vd / RP = IV
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Methodology
PowerManager
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Methodology
• Instrumented components
– CPU– RAM– GSM– GPS– Bluetooth– LCD panel
– WiFi– Backlight– Audio codec– Amplifier– NAND flash– SD card
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Benchmarks
• Micro-benchmarks– Suspend– Idle– Backlight– CPU/RAM
– Flash storage– Network– GPS
• Usage scenarios– Audio– Video– SMS
– Email– Web– Call
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Idle Power
GSM CPU GPU LCD Rest0
10
20
30
40
50
60
70
80
90
Pow
er (
mW
)
Idle: 269 mWSuspend: 69 mW
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Display Power
GSM CPU Display Rest0
100
200
300
400
500
600
Pow
er (
mW
) Backlight
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CPU and RAMeq
uake vp
rgz
ipcr
afty
mcf
idle
0
50
100
150
200
250
Pow
er (
mW
)
equa
ke vpr
gzip
craf
tym
cfid
le
0
50
100
150
200
250100 MHz 400 MHz
RAMCPU
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GSM CPU Display Rest0
50
100
150
200
250
300
350
400
Pow
er (
mW
)
Total: 610 mW
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Video
GSM CPU RAM Display Rest0
20
40
60
80
100
120
140
160
180
Pow
er (
mW
)
Total: 454 mW
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Audio
GSM CPU RAM Display Audio Rest0
20
40
60
80
100
120
140
Pow
er (
mW
)
Total: 320 mW
© NICTA 2010 From imagination to impact
Validation
• Benchmarks repeated on two devices:● HTC Dream (G1)● Google Nexus One (N1)
• Total system power only• 3-4 years of mobile
technology
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Validation
Suspe
nd
Idle
Phone
call
Web
(cell
)
Web
(WiF
i)
Networ
k (c
ell)
Networ
k (W
iFi)
Video
Audio
-80
-60
-40
-20
0
20
40
G1N1
% p
ower
diff
eren
c e
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DVFS
• Dynamic Voltage and Frequency Scaling• DVFS reduces power
… but does it reduce energy?
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DVFS
equake
vprgzip
craftymcf
-30
-20
-10
0
10
20
30
40
FreerunnerG1N1
% e
nerg
y sa
ving
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Conclusions
• Major consumers: display & cell radio‒ WiFi power low in most situations
• CPU can be significant‒ Future power driver
• Where power is not going:– RAM– Audio– Bluetooth– Storage
© NICTA 2010 From imagination to impact
Conclusions
• Both dynamic and static power important• DVFS hanging on (for now)• Networking power not increasing