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Systrace

The systrace tool helps analyze the performance of your application by capturing and displaying execution times of your applications processes and other Android system processes. The tool combines data from the Android kernel such as the CPU scheduler, disk activity and application threads to generate an HTML report that shows an overall picture of an Android device’s system processes for a given period of time.

The systrace tool is particularly useful in diagnosing display problems where an application is slow to draw or stutters while displaying motion or animation. For more information on how to use systrace, see Analyzing Display and Performance with Systrace.

Usage

In order to run systrace, the adb tool and Python must be installed and included in your development computer's execution path. In order to generate a trace, you must connect a device running Android 4.1 (API Level 16) or higher to your development system using a USB debugging connection.

The syntax for running systrace is as follows.

$> python systrace.py [options]

Here is an example execution run that sets trace tags and generates a trace from a connected Android device.

$> cd android-sdk/tools/systrace
$> python systrace.py --set-tags gfx,view,wm
$> adb shell stop
$> adb shell start
$> python systrace.py --disk --time=10 -o mynewtrace.html

Options

The table below lists the command line options for systrace.

Option Description
-o <FILE> Write the HTML trace report to the specified file.
-t N, --time=N Trace activity for N seconds. Default value is 5 seconds.
-b N, --buf-size=N Use a trace buffer size of N kilobytes. This option lets you limit the total size of the data collected during a trace.
-d, --disk Trace disk input and output activity. This option requires root access on the device.
-f, --cpu-freq Trace CPU frequency changes. Only changes to the CPU frequency are logged, so the initial frequency of the CPU when tracing starts is not shown.
-i, --cpu-idle Trace CPU idle events.
-l, --cpu-load Trace CPU load. This value is a percentage determined by the interactive CPU frequency governor.
-s, --no-cpu-sched Prevent tracing of the CPU scheduler. This option allows for longer trace times by reducing the rate of data flowing into the trace buffer.
-w, --workqueue Trace kernel work queues. This option requires root access on the device.
--set-tags=<TAGS> Set the enabled trace tags in a comma separated list. The available tags are:
  • gfx - Graphics
  • input - Input
  • view - View
  • webview - WebView
  • wm - Window Manager
  • am - Activity Manager
  • sync - Sync Manager
  • audio - Audio
  • video - Video
  • camera - Camera

Note: When setting trace tags from the command line, you must stop and restart the framework ($> adb shell stop; adb shell start) for the tag tracing changes to take effect.
--link-assets Link to the original CSS or JS resources instead of embedding them in the HTML trace report.
-h, --help Show the help message.

You can set the trace tags for systrace with your device's user interface, by navigating to Settings > Developer options > Monitoring > Enable traces.

Trace Viewing Shortcuts

The table below lists the keyboard shortcuts that are available while viewing a systrace trace HTML report.

Key Description
w Zoom into the trace timeline.
s Zoom out of the trace timeline.
a Pan left on the trace timeline.
d Pan right on the trace timeline.
e Center the trace timeline on the current mouse location.
g Show grid at the start of the currently selected task.
Shift+g Show grid at the end of the currently selected task.
Right Arrow Select the next event on the currently selected timeline.
Left Arrow Select the previous event on the currently selected timeline.
Double Click Zoom into the trace timeline.
Shift+Double Click Zoom out of the trace timeline.