linux-kernel - Re: [PATCH] thermal: cpu_cooling: Actually trace CPU load in thermal_power_cpu_get

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Message-ID: <20190510063854.GA20477@tesla>
Date:   Fri, 10 May 2019 07:38:54 +0100
From:   Javi Merino <javi.merino@...nel.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH] thermal: cpu_cooling: Actually trace CPU load in
 thermal_power_cpu_get_power

On Thu, May 02, 2019 at 11:32:38AM -0700, Matthias Kaehlcke wrote:
> The CPU load values passed to the thermal_power_cpu_get_power
> tracepoint are zero for all CPUs, unless, unless the
> thermal_power_cpu_limit tracepoint is enabled too:
> 
>   irq/41-rockchip-98    [000] ....   290.972410: thermal_power_cpu_get_power:
>   cpus=0000000f freq=1800000 load={{0x0,0x0,0x0,0x0}} dynamic_power=4815
> 
> vs
> 
>   irq/41-rockchip-96    [000] ....    95.773585: thermal_power_cpu_get_power:
>   cpus=0000000f freq=1800000 load={{0x56,0x64,0x64,0x5e}} dynamic_power=4959
>   irq/41-rockchip-96    [000] ....    95.773596: thermal_power_cpu_limit:
>   cpus=0000000f freq=408000 cdev_state=10 power=416
> 
> There seems to be no good reason for omitting the CPU load information
> depending on another tracepoint. My guess is that the intention was to
> check whether thermal_power_cpu_get_power is (still) enabled, however
> 'load_cpu != NULL' already indicates that it was at least enabled when
> cpufreq_get_requested_power() was entered, there seems little gain
> from omitting the assignment if the tracepoint was just disabled, so
> just remove the check.
> 
> Fixes: 6828a4711f99 ("thermal: add trace events to the power allocator governor")
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>

Yep, looks good to me.

Acked-by: Javi Merino <javi.merino@...nel.org>

> ---
>  drivers/thermal/cpu_cooling.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index f7c1f49ec87f..b437804e099b 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -458,7 +458,7 @@ static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
>  			load = 0;
>  
>  		total_load += load;
> -		if (trace_thermal_power_cpu_limit_enabled() && load_cpu)
> +		if (load_cpu)
>  			load_cpu[i] = load;
>  
>  		i++;
> -- 
> 2.21.0.593.g511ec345e18-goog
>