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Date:   Thu, 9 May 2019 22:08:29 +0900
From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     <lecopzer.chen@mediatek.com>
Cc:     <linux-kernel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <corbet@lwn.net>, <mhiramat@kernel.org>,
        <srv_heupstream@mediatek.com>, <yj.chiang@mediatek.com>
Subject: Re: [PATCH] Documentation: {u,k}probes: add tracing_on before
 tracing
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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>