Ubuntu Wiki

This page details power management measurement metrics for devices typically found in a mobile platform such as a phone or a tablet. This document captures hardware and software system components that can be measured along with possible strategies describing how to test.

Identify metrics useful for system power testing

Power Meter Measurements:

Idle

• Idle with screen on
• Idle with screen off
• Fully suspended with screen off

R/F signals

• Need to put device in Faraday cage

  • http://www.lessemf.com/

GPS

• Off
• On, getting a fix
• On, tracking
  • Action: investigate GPS signal re-radiator into lab

Wifi

• Off
• Associating
  • Time to associate
  • Power to associate
• On + Idle
• On + Not Associated
• Receiving data
• Sending data
  • data Send/Receive scenarios:
    • occasional UDP packets (e.g. every 60 seconds, every 5 seconds, every second)
    • streaming UDP data
    • streaming TCP/IP data

Touchscreen

• Idle
• Being used (how to automate this?)

GSM / HSPA+

• Off
• On + Idle
• Receiving data
• Sending data
• Receving SMS
• Sending SMS
• Phone call

BlueTooth

• Off
• On + Idle
• Set up discovery mode
• Pairing + Bonding
• Send/Receive data

GPU

• Off (?)
• On + Idle
• Playback video
• Render 3D test

Camera

• Off
• On
• Take a photo
  • different resolutions
• Take multiple photos
• Record a video
  • different resolutions

Camera Flash/LED

• Off
• On, flash
• On, long duration

Screen Brightness

• Lowest
• 25%, 50%, 75%
• Highest
  • Nexus 4: /sys/devices/platform/msm_fb.525825/leds/lcd-backlight/brightness

Haptic Feedback

• Vibrate on/off

File System

• Maybe investigate best power saving fs, e.g.
  • Clean a partition and do:
    • format
    • fs populate
    • run known I/O sequences, bonnie++ or tiobench
    • dd write, dd read partion
    • dd write, dd read file system
    • Won't show up 'real world' usage though
  • Need to simulate real use cases.

USB

• lowpower modes? idle?
• send/receive data
• plug/unplug (automate?)
• OTG host mode

CPU

• exercise scheduler:
  • N tasks, different loads on/off
  • cpu affinity
  • cpu scaling
  • voltate level scaling + freq scaling
  • powering off CPUs

Audio Output, Speaker

• off
• idle?
• playing PCM .wav data
  • different rates, 44.1 Hkz, etc
• playing mp3
  • different bit rates

Audio Output, Headphone jack

• not plugged in
• plugged in idle
• playing PCM .wav data
  • different rates, 44.1 Hkz, etc
• playing mp3
  • different bit rates

Audio Input

• off
• on, idle(?)
• on, recording

Sensors

Gyro + Accellerometer

• Off,
• On, Idle
• On (Active)

Proximity Sensor

• Off
• On, Idle
• On, Sensing

Barometer

• Off
• On, Idle
• On, Sensing

Light Sensor

• Off
• On, Idle
• On, Sensing

Misc Tasks

• Identify hardware blocks + PM management in drivers

  • See MobileDevicePM

Other related measurements

Wakeup events

• evenstat etc
• long duration - check for occasional bursty events
• long duration - check for continuous high freq events

General Activity

• idle wakeup event counting
• idle irqs counting
• idle system call counting e.g. "find busy poll()/select() CPU tasks"
• CPU sucking processes
  • tools such as: top, htop, ps, vmstat, etc
• GPU sucking processes

Context Switches

• Identify heavy or unnecessary context switches
  • vmstat like tool, maybe modify eventstat
  • pidstat -w 10 1

Storage

• fatrace
  • look for busy open/close read/write tasks
• fsync, sync

  • use ftrace, see sys_fsync.sh