bytrace Usage Guidelines

Overview

bytrace is a tool for you to trace processes and analyze performance. It encapsulates and extends the kernel ftrace and supports event tracking in the user space. With bytrace, you can open a user-space or kernel-space label you want to view (run the bytrace -l command to query all the supported labels) and run the --trace_begin and -o filename (or --output filename) commands to capture traces and dump them to a specified file.

How to Develop

bytrace supports the following commands:

Table 1 Commands

Option

Description

-h, --help

Views the help text for bytrace.

-b n, --buffer_size n

Sets the size of the buffer (KB) for storing and reading traces. The default buffer size is 2048 KB.

-t n, --time n

Sets the bytrace uptime in seconds, which depends on the time required for analysis.

--trace_clock clock

Sets the type of the clock for adding a timestamp to a trace, which can be boot (default), global, mono, uptime, or perf.

--trace_begin

Starts capturing traces.

--trace_dump

Dumps traces to a specified position (console where you run this command by default).

--trace_finish

Stops capturing traces and dumps traces to a specified position (console where you run this command by default).

-l, --list_categories

Lists the bytrace categories supported by the device.

--overwrite

Sets the action to take when the buffer is full. If this option is used, the latest traces are discarded; if this option is not used, the earliest traces are discarded (default).

-o filename, --output filename

Outputs traces to a specified file.

-z

Compresses a captured trace.

Usage Example

The following are some examples of bytrace commands:

  • Run the following command to query supported labels:
bytrace -l

Alternatively, you can run the following command:

bytrace --list_categories
  • Run the following command to capture traces whose label is ability, with the buffer size set to 4096 KB and bytrace uptime set to 10s:
bytrace -b 4096 -t 10 --overwrite ability > /data/mytrace.ftrace
  • Run the following command to set the clock type for traces to mono:
bytrace --trace_clock mono -b 4096 -t 10 --overwrite ability > /data/mytrace.ftrace
  • Run the following command to compress the captured trace:
bytrace -z -b 4096 -t 10 --overwrite ability > /data/mytrace.ftrace