an analysis of power consumption in a smartphone€¦ · © nicta 2010 from imagination to impact...

© NICTA 2010 From imagination to impact

An Analysis of Power Consumption in a

Smartphone

Aaron Carroll and Gernot Heiser


Motivation


Problem

• Where and how is power consumed in a smartphone?

• Approach: fine-grained instrumentation ofa real device


Methodology

• OpenMoko Freerunner– 2.5G smartphone, c. 2008– 400 MHz ARM9– Lacking camera, 3G modem

– Open design– Amenable to power

instrumentation


Methodology

Device

PowerManager

ADC

0 Ω100 mΩ

I = Vd / RP = IV


Methodology

PowerManager


Methodology

• Instrumented components

– CPU– RAM– GSM– GPS– Bluetooth– LCD panel

– WiFi– Backlight– Audio codec– Amplifier– NAND flash– SD card


Benchmarks

• Micro-benchmarks– Suspend– Idle– Backlight– CPU/RAM

– Flash storage– Network– GPS

• Usage scenarios– Audio– Video– SMS

– Email– Web– Call


Click to edit Master subtitle style

Idle Power

GSM CPU GPU LCD Rest0

10

20

30

40

50

60

70

80

90

Pow

er (

mW

)

Idle: 269 mWSuspend: 69 mW


Click to edit Master subtitle style

Display Power

GSM CPU Display Rest0

100

200

300

400

500

600

Pow

er (

mW

) Backlight


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


Email

GSM CPU Display Rest0

50

100

150

200

250

300

350

400

Pow

er (

mW

)

Total: 610 mW


Video

GSM CPU RAM Display Rest0

20

40

60

80

100

120

140

160

180

Pow

er (

mW

)

Total: 454 mW


Audio

GSM CPU RAM Display Audio Rest0

20

40

60

80

100

120

140

Pow

er (

mW

)

Total: 320 mW


Validation

• Benchmarks repeated on two devices:● HTC Dream (G1)● Google Nexus One (N1)

• Total system power only• 3-4 years of mobile

technology


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


DVFS

• Dynamic Voltage and Frequency Scaling• DVFS reduces power

… but does it reduce energy?


DVFS

equake

vprgzip

craftymcf

-30

-20

-10

0

10

20

30

40

FreerunnerG1N1

% e

nerg

y sa

ving


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


Conclusions

• Both dynamic and static power important• DVFS hanging on (for now)• Networking power not increasing

an analysis of power consumption in a smartphone€¦ · © nicta 2010 from imagination to impact...

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