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An Analysis Of Power Consumption In a Smartphone

An Analysis Of Power Consumption In a Smartphone. Aaron Carroll, Gernot Heiser NICTA, Univ. New South Wales and Open Kernel Lab 2010 USENIX Annual Technical Conference Presented By : 박 세 준. Contents . Intro Benchmark – Overview Benchmark – Components Usage Scenarios

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An Analysis Of Power Consumption In a Smartphone

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  1. An Analysis Of Power Consumption In a Smartphone Aaron Carroll, GernotHeiser NICTA, Univ. New South Wales and Open Kernel Lab 2010 USENIX Annual Technical Conference Presented By : 박 세 준

  2. Contents • Intro • Benchmark – Overview • Benchmark – Components • Usage Scenarios • Validation & Analysis • Conclusion

  3. Introduction • Benchmark Environment • Tested on FreeRunner, validated on HTC Dream, Google Nexus One. • Disregard for power loss from voltage drop.E.g. Power supply from battery to devices • Substitution “real power(total power)” to“aggregate power” • Also disregard for backlight boost converter.

  4. And nothing in there..

  5. Benchmark - Overview • Baseline : Suspended • Equivalent to power-save mode • Data of 3G will be off,only GSM(call, SMS) • RAM doesn’t giveeffect much to result. • GSM subsystem consuming 45% of overall power. • GSM is to be awake, as it continuously communicates with BTS and keeps alive connection with BTS. • GSM doesn’t system memory, it has own. • GSM / Graphics have large RSD

  6. Benchmark - Overview • Baseline : IDLE • Just screen-off. • No foregroundapplication, but thisdoesn’t mean nobackground application. • All network activitiesrun on(=3g data isenabled) • Graphics are busy because of backgroundapplications. • GSM is still consuming large power. • LCD power consumption is derived from LCD touch screen.

  7. Benchmark - Overview • Display More darkness, more battery use..

  8. No free lunch..

  9. Micro Benchmarks • CPU&RAM • X-axisdiffers fromsort of benchmark • Each benchusesparticularCPU / RAMusage • Specific to ram bound or CPU bound

  10. Micro Benchmarks • CPU&RAM • Performance grows bypercentageRAM / CPUutilization. • Performanceis meaninglesssince it shows only data efficiency, so CPU utilization is less important than RAM utilization from data efficiency point of view. More RAM utilization leads more data to access, more data amount. • Energy efficiency is derived from power / performance.

  11. Micro Benchmarks • Flash Storage • Consumed power is measured by Linux dd program. • SD card requires controller, and it continues to more electric power than internal storage.

  12. Micro Benchmarks • Network • Wi-Fi throughput • 600~700KB/s • GPRS throughput • 3~4KB/s • Wi-Fi has greaterhigh speed thanGPRS, of course, consumes more electric power. • GSM(GPRS) showed consistent power consumption. • But in case phone in 2mm-thick metal covered box, GSM showed 30% increased power consumption but same on Wi-Fi.

  13. Micro Benchmarks • GPS • Irrelevant energy consumption to received data amount, number of connected satellites, GPS signal strength, and so on. • Past study for GPS announced if GPS module established with GPS its power consumption would be cut off 30%. But this study has no idea for this inconsistency..

  14. Usage Scenarios • Audio • Play music in SD. • GSM still consumedmuch power. • Audio subsystemconsumed 33.1mW.On the contrast, Graphics consumedabout 90mW, butno mention from paper.Maybe it is from GPUor otherwise case. • On the contrary case in MP3 player, decreasing volume didn’t make influence to result. Instead, consumed power increased.Also, none knows why did it happen.

  15. Usage Scenarios • Video(no sound) • Overall powerconsumptionincreasedcompared withformer case. • Backlight has aextreme influence. • CPU consumedmost of power excluding backlight. • Little change in Graphics and GSM. • We can suppose that audio codec uses power similar with video codec according to consumed power on Graphics.

  16. Usage Scenarios • Phone call • GSM consumedalmost of power. • Backlight contributedvery little comparedwith before case,because of androidpower-saving policy. • However consumed power on GSM is much greater than latter result, it comes usage period rather than difference among consumption of power per unit of time.

  17. Usage Scenarios • Email/Web browsing • Seemed similar between top two results. • Backlight contributed much more than former. • GPRS consumed more power than Wi-Fi, however its throughput much worse. • Similarly with LTE phone, cellular network improvement leads more power consumption, and of course, it will have to be cleared.

  18. Validation • Display(TFT vs OLED)

  19. Validation • CPU (see underline) • Due to SoC and S/Wsupport, G1 has strongerelectric power efficiencythan the others. • But worse efficiency for Wi-Fi network. • Phone call shows thatHSPA has better efficiency than GSM, butthere is no evidencewhether GSM is worse thanHSPA or Freerunner’s SW is worse than G1’s or N1’s SW in this paper.

  20. Analysis • Where do have energy gone? • GSM • Display(Strictly depends onbacklight level) • In a phone call case, GSMtakes almost electric power, however, there isfew things we(software experts) can contribute to solve this problem. It is likely to be hardware bounds, rather than be middleware or higher software layer. • But we can contribute via as like android back light off policy on phone call. It seems to be good and urgent thing that we can handle. • RAM, SD didn’t contribute much consumption.

  21. Analysis • DVFS(Dynamic Voltage and Frequency Scaling) • E means consumed total energy in benchmark. • means average consumed power • means idle power • means max time of benchmark • If DVFS is used, decreases significantly and total energy E drops. • Specially, N1 has quite difference frequency(that is, max of freq – min of freq).This leads power consumption to be cut while N1 frequency drops about minimum.

  22. Analysis • Modeling usage patterns • Suspend : Baseline • Casual : Very little phone utilization. • Regular : Balancing within data, media, call. • Business : Extremely SMS, call utilization. • PMD : Only media, no any communication.

  23. Limitation of this study • Too low android version. • GSM is treated by 2.5G network, but present network has evolved up to 3.9G as like LTE, WIBRO advanced, etc. • Processor used in this study is thought of old-fashioned. Actually, modern processors focused on performance, as well as very limited electric resources.(e.g. Exynos, Tegra, Omap, etc) • (Not in this study) There is sufficient evidence to save battery time with display.(e.g. Super Amoled, Letina display)

  24. Supplement • Android version history(view of power) Jellybean • In éclair, there is many optimization for advanced hardware and UI refresh. • Great performance from improvements with JIT compiler, memory management via automatically termination for application with self-study ability in Froyo. • Gingerbread provides enhanced concurrent garbage collector, ext4 file system, policy for strict power distribution among applications. • Recent Ice cream is armored with force-stop background application, improvements with DB, multimedia components. • Future Jellybean update will contain removal adobe flash and integration google base application, inclusion chrome.

  25. Thanks for attention If we can achieve this infinite resource, I would never have seen this paper..

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