Tips for Using Trepn Profiler

Tuesday 6/10/14 11:00am
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Posted By Rick Schwartz
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Trepn Recent Apps ListRecent Apps List

Trepn Profiler is one of the few Android applications designed to provide accurate power profiling of apps, and there are many power-related elements it is designed to measure including:

  • Which of two similar apps use less power?
  • How much more power does a free app with ads consume over a paid app without ads?
  • Does one mobile device consume more power than another?
  • Do you really save noticeable amounts of power when you enable power saving modes?
  • What is the impact of settings on power consumption (e.g. do you save noticeable amounts of power when you turn off Bluetooth, Wi-Fi or 4G?)
  • Does the new version of an app consume more or less power than the previous version?
  • How much power do the different parts of your mobile device consume (e.g. CPU vs GPU, etc.)? [Only works on Snapdragon MDP developer devices]

But before you start profiling, there are several things you should do to increase your chances of getting the most accurate power measurements possible.

Tips for More Accurate Power Measurements

  • Minimize the number of things running in the background - It’s not enough to close everything in the Recent Apps list shown above. Make sure you also stop anything you don’t want considered in your power readings. Restart your mobile device and go to Settings to view the currently running applications. You may wait a minute for Android housekeeping and app updates to finish before continuing. Then stop any non-essential apps (e.g. Facebook, Google Search, etc.) by touching the “Stop” button. Some apps have multiple processes running that you need to stop, and if you don’t do this, your readings could be artificially high. For example, before closing down unused apps, I measured a reading of 1043mW with my tablet idle. After restarting and closing unused apps, the idle power reading dropped to 726mW. That’s a 30% reduction in power consumption.
  • Make sure you mobile processor stays awake – If you are going to be profiling for more than a minute, you should make sure your mobile processor stays awake to ensure accurate average power readings. To do this, go to the General Settings page in the Trepn app and check “Acquire Wakelock while Profiling.” If you don’t do this, you could end up with average power readings that are much higher than they should be because Trepn will average any spikes over a short time period.  

Trepn Profiler Graph view with wakelocks disabled
          Trepn Profiler Graph view with wakelocks disabled

Here’s an example why this is so important. The chart above and the chart below both profile the same device running idle. Without forcing the processor to stay awake, the average power reading is 1223mW. With a wakelock set, the power measured is 301mW. That’s a difference of over 900mW and shows how important this setting can be. 

Trepn Profiler Graph view with wakelocks disabled
          Trepn Profiler Graph view with wakelocks enabled

  • Minimize the impact of the screen - The screen on a mobile device is normally the biggest user of power. If you want to measure the average power being consumed by your device, and don’t need the screen to be easily readable, you should set the screen timeout to a short value (e.g., 1 minute or less).
  • Focus on what you’re measuring – If you want to measure the power consumption of one thing like Wi-Fi power, go to Settings and turn off everything that is not Wi-Fi related (e.g., GPS, Bluetooth, Mobile networks, etc.) Turning down screen brightness will also help give more accurate readings because the screen is such a big consumer of power.

Measuring Power Usage
Once you’ve completed the above steps, you are ready to profile.

  • First Launch Trepn Profiler
  • Next, go to Settings and select the data points you want to measure. For power consumption tests, select “Battery Power” and uncheck everything else. Before proceeding, make sure your device is on the list of supported devices (shown below). If you see very low power readings like 0 or 1.80mW your device is unsupported and cannot accurately display power. Also check to make sure the device isn’t connected to a charger as that may cause Trepn Profiler to display inaccurate power readings.
  • Press the “Profile System” or “Profile App” buttons to start profiling. If you select “Profile App,” you’ll be asked to pick an app.
  • Next, perform your tests, or measure the power of the device idle.
  • After your tests are finished, press the “Stop Profiling” button and save your results as a .db. Then touch “Save.” It can take a minute or longer to save all of the data collected.
  • Press the “Analyze Run” button and check the desired data.  

Trepn screenshot - profile battery power relative to CPU and GPU usage on a game
Using Trepn to profile battery power relative to CPU and GPU usage on a game

  • Then touch “Analyze,” and view the graphed data and stats. In Graph view you can zoom in or out using the + and – buttons. In Stats view, Trepn displays the average power consumed and estimate of the power that will be consumed in an hour (e.g., mWh).
  • When you are finished, touch the “Close Session” button.

Happy profiling!

Supported Mobile Devices

The following devices have been tested and support battery power measurements:

  • Google/ASUS Nexus 7
  • LG Nexus 4
  • LG Nexus 5
  • HTC One (2013)
  • Sony Xperia ZL
  • HTC Droid DNA
  • LG Optimus G Pro
  • Snapdragon 805 (8084) MDP tablet
  • Snapdragon 800 (8974) MDP tablet
  • Snapdragon 801 (8974 AB) MDP smartphone
  • Snapdragon 800 (8974) MDP smartphone
  • Snapdragon 600 (8064) MDP tablet
  • Snapdragon S4 Pro (8960) MDP smartphone

Known devices which don’t report accurate battery power

  • Samsung Galaxy S III (SCH-I535)
  • Samsung Galaxy S4 (SCH-I545)
  • Samsung Galaxy S5
  • Samsung Galaxy Note II
  • Samsung Galaxy Note 3 (SM-N900V)
  • DragonBoard (all versions)
  • Inforce IFC6410 SBC