xref: /aosp_15_r20/external/trace-cmd/Documentation/trace-cmd/trace-cmd-reset.1.txt (revision 58e6ee5f017f6a8912852c892d18457e4bafb554)

TRACE-CMD-RESET(1)
==================

NAME
----
trace-cmd-reset - turn off all Ftrace tracing to bring back full performance

SYNOPSIS
--------
*trace-cmd reset* ['OPTIONS']

DESCRIPTION
-----------
The trace-cmd(1) reset command turns off all tracing of Ftrace. This will
bring back the performance of the system before tracing was enabled. This is
necessary since 'trace-cmd-record(1)', 'trace-cmd-stop(1)' and
'trace-cmd-extract(1)' do not disable the tracer, event after the data has
been pulled from the buffers. The rational is that the user may want to
manually enable the tracer with the Ftrace pseudo file system, or examine other
parts of Ftrace to see what trace-cmd did. After the reset command happens,
the data in the ring buffer, and the options that were used are all lost.

OPTIONS
-------
Please note that the order that options are specified on the command line is
significant. See EXAMPLES.

*-b* 'buffer_size'::
    When the kernel boots, the Ftrace ring buffer is of a minimal size (3
    pages per CPU). The first time the tracer is used, the ring buffer size
    expands to what it was set for (default 1.4 Megs per CPU).

    If no more tracing is to be done, this option allows you to shrink the
    ring buffer down to free up available memory.

    trace-cmd reset -b 1

    The buffer instance affected is the one (or ones) specified by the most
    recently preceding *-B*, *-t*, or *-a* option:

    When used after *-B*, resizes the buffer instance that precedes it on
    the command line.

    When used after *-a*, resizes all buffer instances except the top one.

    When used after *-t* or before any *-B* or *-a*, resizes the top
    instance.

*-B* 'buffer-name'::
    If the kernel supports multiple buffers, this will reset the trace for
    only the given buffer. It does not affect any other buffer. This may be
    used multiple times to specify different buffers. The top level buffer
    will not be reset if this option is given (unless the *-t* option is
    also supplied).

*-a*::
    Reset the trace for all existing buffer instances. When this option
    is used, the top level instance will not be reset unless *-t* is given.

*-d*::
    This option deletes the instance buffer(s) specified by the most recently
    preceding *-B* or *-a* option. Because the top-level instance buffer
    cannot be deleted, it is invalid to use this immediatly following *-t* or
    prior to any *-B* or *-a* option on the command line.

*-t*::
    Resets 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 reset.

EXAMPLES
--------

Reset tracing for instance-one and set its per-cpu buffer size to 4096kb.
Also deletes instance-two. The top level instance and any other instances
remain unaffected:

    trace-cmd reset -B instance-one -b 4096 -B instance-two -d

Delete all instance buffers. Top level instance remains unaffected:

    trace-cmd reset -a -d

Delete all instance buffers and also reset the top instance:

    trace-cmd reset -t -a -d

Invalid. This command implies an attempt to delete the top instance:

    trace-cmd reset -a -t -d

Reset the top instance and set its per-cpu buffer size to 1024kb. If any
instance buffers exist, they will be unaffected:

    trace-cmd reset -b 1024


SEE ALSO
--------
trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(1),
trace-cmd-stop(1), trace-cmd-extract(1), trace-cmd-split(1),
trace-cmd-list(1), trace-cmd-listen(1)

AUTHOR
------
Written by Steven Rostedt, <[email protected]>

RESOURCES
---------
https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/

COPYING
-------
Copyright \(C) 2010 Red Hat, Inc. Free use of this software is granted under
the terms of the GNU Public License (GPL).