linux-kernel - Re: [PATCH v6 4/5] devfreq_cooling: add trace information

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Date:	Thu, 10 Sep 2015 13:19:28 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Javi Merino <javi.merino@....com>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	cw00.choi@...sung.com, edubezval@...il.com,
	Zhang Rui <rui.zhang@...el.com>, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v6 4/5] devfreq_cooling: add trace information

On Thu, 10 Sep 2015 18:09:31 +0100
Javi Merino <javi.merino@....com> wrote:

> Tracing is useful for debugging and performance tuning.  Add similar
> traces to what's present in the cpu cooling device.
> 
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Signed-off-by: Javi Merino <javi.merino@....com>
> ---
>  drivers/thermal/devfreq_cooling.c |  6 +++++
>  include/trace/events/thermal.h    | 53 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 59 insertions(+)
> 
> diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
> index a032c5d5c374..a27206815066 100644
> --- a/drivers/thermal/devfreq_cooling.c
> +++ b/drivers/thermal/devfreq_cooling.c
> @@ -25,6 +25,8 @@
>  #include <linux/pm_opp.h>
>  #include <linux/thermal.h>
>  
> +#include <trace/events/thermal.h>
> +
>  static DEFINE_MUTEX(devfreq_lock);
>  static DEFINE_IDR(devfreq_idr);
>  
> @@ -293,6 +295,9 @@ static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cd
>  	/* Get static power */
>  	static_power = get_static_power(dfc, freq);
>  
> +	trace_thermal_power_devfreq_get_power(cdev, status, freq, dyn_power,
> +					      static_power);
> +
>  	*power = dyn_power + static_power;
>  
>  	return 0;
> @@ -348,6 +353,7 @@ static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
>  			break;
>  
>  	*state = i;
> +	trace_thermal_power_devfreq_limit(cdev, freq, *state, power);

I'm curious, does changing the above to:

	trace_thermal_power_devfreq_limit(cdev, freq, i, power);

make the compiled code better?

A tracepoint does some whacky things, and gcc may not optimize this.

The rest looks fine to me.

-- Steve

>  	return 0;
>  }
\
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