trace-cmd-extract - extract out the data from the Ftrace Linux
trace-cmd extract [OPTIONS]
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
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.
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
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 event.
By default, the extract command will create a
trace.dat file. This option will change where the file is written
Extract from the snapshot buffer (if the kernel supports
This is the same as the trace-cmd-record(1)
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
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 extracted.
Written by Steven Rostedt,
Copyright (C) 2010 Red Hat, Inc. Free use of this software is
granted under the terms of the GNU Public License (GPL).