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Date:   Tue, 19 Dec 2017 18:30:11 +0000
From:   Marc Zyngier <>
To:     Viresh Kumar <>,
        Catalin Marinas <>
Cc:     Vincent Guittot <>,,
        Will Deacon <>,,
Subject: Re: [PATCH] arm64: defconfig: Select schedutil as default cpufreq

On 18/12/17 04:29, Viresh Kumar wrote:
> On 15-12-17, 15:50, Catalin Marinas wrote:
>> On Thu, Nov 16, 2017 at 11:51:36AM +0530, Viresh Kumar wrote:
>>> Currently performance governor is getting selected by default, which is
>>> surely not a very good choice as its pretty much power hungry.
>>> Select schedutil instead.
>> And why do we care about this in defconfig? People deploying their own
>> kernels in mobile may opt for this config, others may prefer the default
>> governor.
>> Also it seems it would be the only architecture make this governor the
>> default, so NAK.
> This is a bit dangerous configuration IMHO.
> Other architectures have some *real* governor selected by default, like Ondemand
> or Conservative. Running your CPUs at max (because of the default performance
> governor in arm64 config) may end up burning some SoCs accidentally just because
> their thermal stuff doesn't kick in to cool SoC down properly.

Honestly, this feels like widening a road because someone wants to drive
a car with no steering wheel. If an SoC is broken enough not to to into
thermal throttling on its own, I'm tempted to say "let it burn".

And on-demand is just as bad as performance in that respect, as it will
to the same thing as soon as you run (for example) Firefox. Or Emacs.

> So, we should have one of ondemand, conservative and schedutil selected by
> default for arm64 as well IMO and schedutil is the one which every one is
> falling back to now a days, even android.

I'll have my bike shed painted pink, thank you very much! :-)

Jazz is not dead. It just smells funny...

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