linux-kernel - Re: [PATCH 1/3] arm64: defconfig: Enable CONFIG_ENERGY

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Date:   Thu, 28 Mar 2019 20:51:12 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Quentin Perret <quentin.perret@....com>
Cc:     edubezval@...il.com, javi.merino@...nel.org,
        viresh.kumar@...aro.org, amit.kachhap@...il.com, rjw@...ysocki.net,
        will.deacon@....com, catalin.marinas@....com,
        dietmar.eggemann@....com, ionela.voinescu@....com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Zhang Rui <rui.zhang@...el.com>
Subject: Re: [PATCH 1/3] arm64: defconfig: Enable CONFIG_ENERGY_MODEL

On 28/03/2019 18:42, Quentin Perret wrote:
> Hi Daniel,
> 
> On Thursday 28 Mar 2019 at 18:27:49 (+0100), Daniel Lezcano wrote:
>> On 28/03/2019 11:22, Quentin Perret wrote:
>>>> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
>>>> index 2d9c39033c1a..3c09bdaaefd3 100644
>>>> --- a/arch/arm64/configs/defconfig
>>>> +++ b/arch/arm64/configs/defconfig
>>>> @@ -97,6 +97,7 @@ CONFIG_XEN=y
>>>>  CONFIG_COMPAT=y
>>>>  CONFIG_HIBERNATION=y
>>>>  CONFIG_WQ_POWER_EFFICIENT_DEFAULT=y
>>>> +CONFIG_ENERGY_MODEL=n
>>>
>>> Hmm, sorry I turned this to '=n' for testing and forgot to update the
>>> patch. This obviously should be '=y' ...
>>
>> I did a test without the ENERGY_MODEL config option set, dhrystone and
>> the power_allocator policy on the hikey. The board did not mitigate well
>> and ended up rebooting.
> 
> OK ... And is the same thing happening if you just run mainline w/o the
> dynamic-power-coefficient binding set for example ? The result _should_
> be the same. 

Right, it is the same.

> If not, then perhaps I missed something. I'll try to
> reproduce on my end. Just to be sure, when you say hikey, you mean
> hikey960 ? Or 620 ? In any case, thanks for testing :-)

hikey620

>> May be the cpu cooling Kconfig option should add
>> a SELECT or a DEPENDS on ENERGY_MODEL ?
> 
> Right, I've been wondering the same thing. I'm not a big fan of 'select'
> because enabling ENERGY_MODEL automatically for the thermal stuff will
> also happen to enable other things (EAS) without the user knowing. So
> I'd rather keep the ENERGY_MODEL option explicit.
> 
> But perhaps having THERMAL_GOV_POWER_ALLOCATOR 'depend on ENERGY_MODEL'
> could work. It's just that there is no _strong_ dependency, the IPA code
> isn't supposed to crash even if there is no EM ...

Given if the ENERGY_MODEL is not set there is a regression we should add
the dependency IMO.


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