FAQ

General

Why does Trepn crash when I start profiling?
It’s possible that Trepn does not have the proper permissions enabled for profiling. Go to the Android Settings menu and select Apps. Tap the gear icon in the upper-right corner of the screen (your device’s UI may vary). Then select 'Draw over other apps,' scroll down to Trepn Profiler, and make sure ‘Permit drawing over other apps’ is enabled.

Does Trepn run on mobile devices without a Snapdragon processor?
Trepn Profiler runs on smartphones and tablets running Android 4.0 or later. However, there are extra capabilities when using a mobile device with a Snapdragon processor including the following:

  • Accurate battery power in mW on supported devices
  • GPU frequency and load
  • Wi-Fi and cellular data by application
    • Older Snapdragon chipsets (8960 and earlier) do not support this feature
  • Screen brightness values

What devices report accurate battery power?
Check the list of Trepn supported devices. If your device is not listed, you can test it by touching the beaker icon in the upper right-hand corner, going to Settings/Data Points and selecting Battery Power. Then press the Back button and touch Profile System and Stats. If you see power values when your device is idle in the following range, it is reporting accurate battery power:

  • 4” to 5” smartphone – 400 mW to 800 mW
  • 6” smartphone/7” tablet – 700 mW to 2500mW
  • 10” tablet – 2000 mW to 4000 mW

Is there a way to save the results of a profiling session so I can analyze the data later?

  1. Touch the beaker icon in the upper right-hand corner to enter Advanced Mode.
  2. Go to Settings/Data Points and check the items you want to profile.  
  3. Press the Back button and select Profile System or Profile App. Then select Overlays, Graph or Stats.
  4. After you have finished profiling, touch the Stop Profiling button. If you don’t see it on the screen, pull down the notification shade and select Trepn.
  5. Then select Save as .db and Save to save your data in a format that Trepn can analyze at a later time.

Where are Trepn files saved on my mobile device?

  1. Use an app like ES File Explorer to browse the stored files on your mobile device. You can also connect your device to your computer and use MTP to mount your device on your desktop.
  2. Scroll down the list of folders until you see a folder called “trepn”
  3. Select the desired file(s) and use More and Share to send it via email, or upload it to a cloud storage locker like Google Drive.

How can I submit feature requests or bug reports?
Feature requests and other feedback can be sent to: trepnfeedback@qti.qualcomm.com. There is also a Trepn forum where you can post questions.

Advanced FAQ

Why do I get a message that says ‘SD Card Unmounted’ when I try to stop profiling data in Advanced mode?
This could mean that Trepn doesn’t have permission to write to storage. Select ‘Don’t Save’ and go to the Android Settings menu. Go to ‘Apps’ and scroll down to Trepn Profiler. Select ‘Permissions’ and make sure ‘Storage’ is enabled.

Is there a way to profile with Trepn in the background and nothing on the screen?

  1. Yes, touch the beaker icon in the upper right-hand corner to enter Advanced Mode.
  2. Go to Settings/Overlays and touch each overlay that doesn’t say “No overlay selected.”
  3. Next, change the overlay type to None and touch OK.
  4. Now, touch the Back button and profile either the system or an app and select Overlays.
  5. After you have finished profiling, touch the Stop Profiling button. If you don’t see it on the screen, pull down the notification shade and select “Trepn.“

Is there a list of things that Trepn can profile?
By going to Settings you can select any of the following data points:

  • CPU stats: Overall CPU Load, Normalized CPU Load, Core 1 Frequency, Core 1 Load, Core 2 Frequency, Core 2 Load, etc. (up to eight cores can be visible at once)
  • GPU stats: GPU Frequency, GPU Load
    • Not all data points are available on all devices. Data points may change depending on manufacturer and chipset.
  • Power stats: Battery power,1 Percent battery remaining
  • Network states: Bluetooth state, Mobile data state, Wi-Fi state, Wi-Fi RSSI level
  • Screen stats: Screen brightness (%), Screen state (on/off)
    • Not all data points are available on all devices. Data points may change depending on manufacturer and chipset.
  • Other stats: Wi-Fi and cellular data by application, Application state, GPS state, Memory usage, Wakelocks, and Wi-Fi locks
    • Wakelocks and Wi-Fi locks are only available on devices that run Android 4.3 or earlier.

How can I profile the power usage of a single app?
Power measurements for a single app can be achieved with a feature called Show Deltas. If the Battery Power data point and Show Deltas are selected when a Trepn profiling session is started, the current battery power is measured and it becomes the baseline.  For the rest of the session, the battery power that is shown will be a delta value that shows how much more power is being used than when the baseline was measured. Here are detailed instructions how to profile the power usage of a single app:

  1. Close your application.
  2. Select Battery Power and Show Deltas settings in Trepn Profiler.
  3. Select Profile an App in Trepn Profiler.
  4. Select your application from the app list.
  5. A baseline is calculated and then your application is launched and Trepn Profiler begins profiling.
  6. The power that your application uses will be included in the value that you see on the graph.

This version of Trepn is very different than earlier versions. Is there a way to access all of the previous functionality?
Yes. Touch the beaker icon in the upper right-hand corner of the home screen to enter Advanced Mode, which contains all of the functionality of earlier Trepn Profiler versions.

How can I change the left axis units on a profiling graph?
Double-tab the vertical axis to switch between all of the unit types.

How can I configure Trepn to display overlays for an octa-core processor on a tablet?

  1. Go to Settings/Data Points and ensure that CPU load or CPU frequency are checked for all eight cores. Uncheck all other data points.
  2. Go to Settings/Overlays and touch each overlay that says “No overlay selected” and touch where it says None and select Graph.
  3. Next, setup CPU frequency (or CPU load) as shown below.

         

The ‘CPU Frequency Overlay’ preset only shows the first four cores of my Snapdragon 810 processor. Are these the ‘big’ or the ‘LITTLE’ cores?
The ‘LITTLE’ cores are shown by default (CPU 1-4). If you setup Trepn so all eight cores are displayed as described above, CPU 5-8 are the ‘big’ cores.

How often does Trepn Profiler collect data?
By default Trepn Profiler collects data once every 100ms resulting in 10 samples every second.

How much of the CPU does Trepn Profiler consume?
The amount of CPU that Trepn Profiler consumes depends on the number of data points selected and the sampling interval. An estimate would be 20-30% of a quad-core CPU.

How can I reduce the number of CPU cycles that Trepn Profiler consumes?
There are several ways you can reduce the amount of CPU load that Trepn Profiler consumes:

  1. Go to Settings/General and select Profiling Interval. Change the value to 300ms or larger. The higher the value, the lower the amount of data collected.
  2. Go to Settings/Data Points and make sure only a few data points are checked.
  3. Go to Settings/Overlays and touch each overlay that doesn’t say “No overlay selected.” Then, change the overlay type to None and touch OK. Then touch the Back button and profile the system or an app.
  4. Finally, press the Back button until you return to the Android home screen.

What are the differences between Profile System and Profile Apps?
There are no major differences between using the Profile System and Profile App options. It's primarily used for convenience - such as launching the application when baselining is complete (when using the Show Deltas option) and saving information in the database about the application being tested.

What is the difference between CPU Load and CPU Load Normalized?
CPU Load reports the usage with respect to the operating frequency. CPU Load – Normalized reports the usage with respect to the maximum frequency. For example, if a single-core CPU has a maximum frequency of 1000 MHz but the workload is low, the system scales the CPU down to 500 MHz (in one second, there are 500M clock cycles). If the device uses 100M of those cycles for work and is idle for the remaining cycles. CPU Load would show 20% (100/500). However, the maximum potential of the CPU was 1000M cycles, so CPU Load - Normalized would show 10% (100/1000).

Does Trepn run on non-mobile devices running Android software?
No. Trepn Profiler does not run on Android TV, Android Wear or other non-mobile devices.

Developer FAQ

Can I insert markers in my code that appear in Trepn Profiler?
The Application State feature of Trepn Profiler is a way to correlate a block of your app’s code, or an event in your application, to the data points that Trepn is profiling. You can isolate sections of your code and discover which blocks have power or usage spikes. Application states work by placing a small piece of code in your application which sends an Android system intents to Trepn Profiler. These can include an application state integer value and an optional text description.  A marker for the application state is recorded in the profiling session and graphed.

How can I reduce power usage in my application?
Trepn Profiler allows you to profile the battery power being used while running the app.  This can be utilized several ways:

  • You can monitor data points such as Data State, CPU Load and GPU Load (on supported devices) to identify what hardware modules your app is using most. Based on this information, you can reduce the activity of that hardware component and reduce overall power usage.
  • Use the Application State to pinpoint where in your code there are power spikes.  This allows for focused analysis of those areas to improve power efficiency.
  • Run two profiling sessions where some code was modified between the two and compare the battery power values to see which code implementation was more power efficient.

Do you have suggestions on how to get accurate power measurements?
Yes, please refer to our Best Practices post in the Trepn Profiler forum.

How can I determine if my app is CPU bound or GPU bound?
You can profile CPU Load – Normalized and GPU Load and see if either of them are maxed at 100% while your app is running.

  • If either CPU or GPU is maxed (or both), your app is bound by that component(s).
  • if neither is maxed, your app is neither CPU nor GPU bound

    Note: GPU Load is only available on Snapdragon MDPs and other select devices with Snapdragon processors.
How can I use scripts with Trepn?
Trepn Profiler can receive several types of Android intents, which can be used to control your profiling sessions. These intents can be issued from a PC’s command prompt or from a script and allow you to start or stop profiling. These commands can also be sent to Trepn Profiler from an Android application on the device.

Script commands include:

  • Start profiling
  • Stop profiling
  • Save current preferences
  • Load saved preferences
  • Change the Application State