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 1000 mΩΩ 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 ) 60 W m 50 ( r e 40 Click to edit Master subtitle style w o 30 P 20 10 0 GSM CPU GPU LCD Rest © NICTA 2010 From imagination to impact Display Power 600 500 ) 400 Backlight W m ( 300 r e Click to edit Master subtitle style w o 200 P 100 0 GSM CPU Display Rest © NICTA 2010 From imagination to impact CPU and RAM 250 200 ) W 150 m 100 MHz r ( we 100 Po 50 0 © NICTA 2010 RAM equake CPU vpr gzip 250 200 crafty 150 mcf 100 400 MHz idle From imagination to impact 50 0 equake vpr gzip crafty mcf idle Email 400 350 Total: 610 mW 300 ) 250 W m ( 200 r e w 150 o P 100 50 0 GSM CPU Display Rest © NICTA 2010 From imagination to impact Video 180 160 Total: 454 mW 140 ) 120 W 100 m ( r e 80 w o 60 P 40 20 0 GSM CPU RAM Display Rest © NICTA 2010 From imagination to impact Audio 140 120 Total: 320 mW 100 ) W 80 m ( r e 60 w o 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 e c n re 40 e iff d 20 r e Suspend w o 0 p Idle % -20 -40 Phone call -60 Web (cell) © NICTA 2010-80 Web (WiFi) Network (cell) Network (WiFi) Video From imagination to impact Audio G1 N1 DVFS • Dynamic Voltage and Frequency Scaling • DVFS reduces power … but does it reduce energy? © NICTA 2010 From imagination to impact DVFS 40 g in 30 v equake a s 20 y g r e 10 vpr n e % 0 gzip -10 -20 crafty -30 © NICTA 2010 mcf From imagination to impact Freerunner G1 N1 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.