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 of a 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
© NICTA 2010 From imagination to impact Methodology
100 m0 ΩΩ Power Manager Device
ADC I = Vd / R P = IV
© NICTA 2010 From imagination to impact Methodology
Power Manager
© NICTA 2010 From imagination to impact Methodology
• Instrumented components
– CPU – WiFi – RAM – Backlight – GSM – Audio codec – GPS – Amplifier – Bluetooth – NAND flash – LCD panel – SD card
© NICTA 2010 From imagination to impact Benchmarks
• Micro-benchmarks – Suspend – Flash storage – Idle – Network – Backlight – GPS – CPU/RAM
• Usage scenarios – Audio – Email – Video – Web – SMS – Call
© NICTA 2010 From imagination to impact Idle Power
90 Suspend: 69 mW 80 Idle: 269 mW 70
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P 20 10 0 GSM CPU GPU LCD Rest
© NICTA 2010 From imagination to impact Display Power
600
500
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m
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300
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o 200
P
100
0 GSM CPU Display Rest
© NICTA 2010 From imagination to impact CPU and RAM
100 MHz 400 MHz 250 250 RAM 200 200 CPU
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© NICTA 2010 From imagination to impact Email
400 350 Total: 610 mW 300
) 250
W
m
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200
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P 100 50 0 GSM CPU Display Rest
© NICTA 2010 From imagination to impact Video
180 160 Total: 454 mW 140
) 120
W 100
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P 40 20 0 GSM CPU RAM Display Rest
© NICTA 2010 From imagination to impact Audio
140
120 Total: 320 mW 100
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W 80
m
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e 60
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P 40
20
0 GSM CPU RAM Display Audio Rest
© 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
© NICTA 2010 From imagination to impact Validation
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© NICTA 2010 From imagination to impact DVFS
• Dynamic Voltage and Frequency Scaling • DVFS reduces power … but does it reduce energy?
© NICTA 2010 From imagination to impact DVFS
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© NICTA 2010 From imagination to impact 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
© NICTA 2010 From imagination to impact