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Energy and Power Measurement on Mobile Devices

3c332dfc0b438785cb10c5234652dd66?s=47 Yuhao Zhu
October 10, 2017

Energy and Power Measurement on Mobile Devices

Tutorial in MobiTools co-located with ISCA 2016


Yuhao Zhu

October 10, 2017

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  1. Energy and Power Measurement on Mobile Devices Yuhao Zhu (@yzhu88)

    The University of Texas at Austin MobiTools 2016 1
  2. 2 You can’t fix what you can’t measure

  3. 3 8 6 4 2 0 Measured Peak Power (W)

    Droid Galaxy S Galaxy Nexus Galaxy S3 Galaxy S4 Galaxy S5 Galaxy S6 (2009) (2010) (2011) (2012) (2013) (2014) (2015) Display Radio CPU T H R OT T L I N G
  4. Measurement Granularity ▸Entire device ▹SoC, Radio, Screen ▸SoC ▹CPU, GPU,

    Memory, DSP, other accelerators ▸Component: CPU/GPU/Memory 4
  5. Hardware Platform ▸Smartphone (tablets, etc.) ▹Mostly close-sources ▸Development board ▹Designed

    for hacking ▹Mostly open-source (schematic, PCB design, etc.) ▹SoC with peripherals (WiFi, USB, etc.) ▹Typically does not come with a screen 5
  6. Measurement Visibility 6 Smartphone Dev board Device SoC Component

  7. Power Measurement Tools ▸NI DAQ ▹A range of choices (sampling

    rate, channels, price) ▹An example of a high-end DAQ - 2M samples per second - 8 channels, 16 bit resolution - ~$4400 ▹ An example of a low-end DAQ - 10k samples per second - 8 channels, 12 bit resolution - $149 7
  8. A Typical DAQ Setup 8 + - Vin+ Vin- Vout

    GND Sense resistor 15mΩ SoC ARM Cortex A9 VRM Gain x50 Probe ▸Do you need an amplifier circuit? ▸Before or after the VRM?
  9. 9 Power Measurement Tools ▸Monsoon ▹5k samples per second ▹1

    channels, 16 bit resolution ▹~$770 ▹Built-in sense resistor (the reason why people use it!!!)
  10. 10 Data Processing Software ▸NI LabView ▹ Specifically designed for

    NI DAQ ▹ Rich API for manipulating data, well integrated with IDEs
  11. ▸Monsoon software 11 Data Processing Software

  12. ARM DS-5 Streamline 12

  13. ARM DS-5 Streamline 13

  14. ▸Correlate over a timeline all your software execution activity with

    power ▸Specifications ▹No built-in sense resistors ▹10k samples per second ▹3 channels, 10 bit resolution ▸No programming APIs 14 ARM DS-5 Streamline
  15. BattOr: Portable Power Monitor ▸ Store power measurements while mobile,

    stream power measurements while stationary. ▸ Open source: https://github.com/aschulm/battor ▸ Integrated into Android and Chrome trace viewer 15
  16. Conclusions 16 Smartphone Dev board Device SoC Component ▸DAQ ▸Monsoon

    ▸BattOr ▸Streamline