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authorLecopzer Chen <lecopzer.chen@mediatek.com>2019-05-09 13:31:16 +0300
committerJonathan Corbet <corbet@lwn.net>2019-06-07 20:56:51 +0300
commit78a89463a31ce463a4b968553f57ff9932a0697f (patch)
tree2bd19f254013908911c754e1fa954f67a65a20cb /Documentation/trace
parent462e5a521ab73f7762583add73cbab1662612beb (diff)
downloadlinux-78a89463a31ce463a4b968553f57ff9932a0697f.tar.xz
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>
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/kprobetrace.rst6
-rw-r--r--Documentation/trace/uprobetracer.rst7
2 files changed, 12 insertions, 1 deletions
diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
index 235ce2ab131a..baa3c42ba2f4 100644
--- a/Documentation/trace/kprobetrace.rst
+++ b/Documentation/trace/kprobetrace.rst
@@ -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.
::
diff --git a/Documentation/trace/uprobetracer.rst b/Documentation/trace/uprobetracer.rst
index 4346e23e3ae7..0b21305fabdc 100644
--- a/Documentation/trace/uprobetracer.rst
+++ b/Documentation/trace/uprobetracer.rst
@@ -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.