linux-kernel - Re: [PATCH] tracing: Only benchmark the time tracepoints take if tracing is on

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Date:	Tue, 27 Oct 2015 22:28:16 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Chunyan Zhang <zhang.chunyan@...aro.org>
Cc:	mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: Only benchmark the time tracepoints take if
 tracing is on

On Tue, 27 Oct 2015 20:12:13 +0800
Chunyan Zhang <zhang.chunyan@...aro.org> wrote:

> There's no need to record the time tracepoints take when tracing is off.
> This is because:
> 1) We cannot see these records since ring_buffer record is off at that
> moment.
> 2) If tracing is off and benchmark tracepoint is enabled, the time
> tracepoint takes is fewer than the same situation when tracing is on,
> since the tracepoints need to be wrote into ring_buffer, it would
> take more time. If turn on tracing at this moment, the average and
> standard deviation cannot exactly present the time that tracepoints
> take to write data into ring_buffer.
> 

Thanks! I'll add this when I get back from traveling.

-- Steve


> Signed-off-by: Chunyan Zhang <zhang.chunyan@...aro.org>
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