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SubjectRe: [PATCH] Documentation: {u,k}probes: add tracing_on before tracing
On Thu, 9 May 2019 18:31:16 +0800
<lecopzer.chen@mediatek.com> wrote:

> From: Lecopzer Chen <lecopzer.chen@mediatek.com>
>
> 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@kernel.org>

Thanks!

>
> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
> ---
> 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@kernel.org>

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