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

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Date:   Fri, 3 May 2019 23:11:23 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Matthias Kaehlcke <mka@...omium.org>,
        Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Javi Merino <javi.merino@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>
Cc:     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 02/05/2019 20:32, 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>
> ---

Yes, load_cpu is needed in any case for both traces. The change makes sense.

Reviewed-by: Daniel Lezcano <daniel.lezcano@...aro.org>


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