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

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Message-ID: <20190329090320.qzsgaytwfyxx4oq3@queper01-ThinkPad-T460s>
Date:   Fri, 29 Mar 2019 09:03:23 +0000
From:   Quentin Perret <quentin.perret@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
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 Thursday 28 Mar 2019 at 20:51:12 (+0100), Daniel Lezcano wrote:
> 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.

OK.

> 
> > 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.

Right, that is true. And there are folks who don't use the arm64
defconfig downstream, so I guess we need to make it clear for them they
need to enable ENERGY_MODEL from now on.

I'll add a 'depends on ENERGY_MODEL' to 'THERMAL_GOV_POWER_ALLOCATOR' in
patch 3 for v2.

Thanks,
Quentin