On Thu, 9 May 2019 18:31:16 +0800 <lecopzer.chen@xxxxxxxxxxxx> wrote: > From: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx> > > 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. OK, but isn't tracing_on enabled by default? Anyway, it looks good to me (for making sure the trace is enabled). Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Thanks! > > Signed-off-by: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx> > --- > Documentation/trace/kprobetrace.rst | 6 ++++++ > Documentation/trace/uprobetracer.rst | 7 ++++++- > 2 files changed, 12 insertions(+), 1 deletion(-) > > 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. > -- > 2.18.0 > -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
