The trace-cmd(1) extract is usually used after trace-cmd-start(1) and
trace-cmd-stop(1). It can be used after the Ftrace tracer has been
started manually through the Ftrace pseudo file system.
The extract command creates a trace.dat file that can be used by
trace-cmd-report(1) to read from. It reads the kernel internal ring
buffer to produce the trace.dat file.
Although extract does not start any traces, some of the plugins
require just reading the output in ASCII format. These are the
latency tracers, since the latency tracers have a separate
internal buffer. The plugin option is therefore only necessary
for the wakeup, wakeup-rt, irqsoff, preemptoff and preemptirqsoff
With out this option, the extract command will extract from the internal
If a latency tracer is being extracted, and the -p option is
used, then there are some Ftrace options that can change the
format. This will update those options before extracting. To see
the list of options see trace-cmd-list. To enable an option,
write its name, to disable the option append the characters no to
it. For example: noprint-parent will disable the print-parent
option that prints the parent function in printing a function
By default, the extract command will create a trace.dat file.
This option will change where the file is written to.
Extract from the snapshot buffer (if the kernel supports it).
This is the same as the trace-cmd-record(1) --date option, but it
does cause the extract routine to disable all tracing. That is,
the end of the extract will perform something similar to
If the kernel supports multiple buffers, this will extract the
trace for only the given buffer. It does not affect any other
buffer. This may be used multiple times to specify different
buffers. When this option is used, the top level instance will
not be extracted unless -t is given.
Extract all existing buffer instances. When this option is used,
the top level instance will not be extracted unless -t is given.
Extracts the top level instance buffer. Without the -B or -a
option this is the same as the default. But if -B or -a is used,
this is required if the top level instance buffer should also be
This page is part of the trace-cmd (a front-end for Ftrace) project.
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know, please contact email@example.com] If you have a bug report for
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