Documentation: {u,k}probes: add tracing_on before tracing

After following the document step by step, the `cat trace` can't be
worked without enabling tracing_on and might mislead newbies about
the functionality.

Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Lecopzer Chen 2019-05-09 18:31:16 +08:00 committed by Jonathan Corbet
parent 462e5a521a
commit 78a89463a3
2 changed files with 12 additions and 1 deletions

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@ -189,6 +189,12 @@ events, you need to enable it.
echo 1 > /sys/kernel/debug/tracing/events/kprobes/myprobe/enable
echo 1 > /sys/kernel/debug/tracing/events/kprobes/myretprobe/enable
Use the following command to start tracing in an interval.
::
# echo 1 > tracing_on
Open something...
# echo 0 > tracing_on
And you can see the traced information via /sys/kernel/debug/tracing/trace.
::

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@ -152,10 +152,15 @@ events, you need to enable it by::
# echo 1 > events/uprobes/enable
Lets disable the event after sleeping for some time.
Lets start tracing, sleep for some time and stop tracing.
::
# echo 1 > tracing_on
# sleep 20
# echo 0 > tracing_on
Also, you can disable the event by::
# echo 0 > events/uprobes/enable
And you can see the traced information via /sys/kernel/debug/tracing/trace.