trace-cmd-reset - Man Page

trace-cmd reset [Options]

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​.

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 immediately 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​.

-k dynevent-name

This option allows preserving specified dynamic event during reset​. Valid parameters are kprobe, kretprobe, uprobe, uretprobe, eprobe, synth and all (for keeping all dynamic events)​. This may be used multiple times to specify different dynamic event types​.

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

Prevent kprobes and kretprobes from being destroyed during reset:

trace-cmd reset -k kprobe -k kretprobe

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)

Written by Steven Rostedt, <rostedt@goodmis​.org​^[1]>

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

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

1.

rostedt@goodmis.org
mailto:rostedt@goodmis.org