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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	SoC Team <soc@kernel.org>, arm-soc <arm@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] ARM: config: multi_v7 Use schedutil cpufreq
Date: Fri, 27 Mar 2020 10:37:27 +0530
Message-ID: <20200327050727.yxzu4b5mu2rdkdz4@vireshk-i7> (raw)
In-Reply-To: <CACRpkdaYo0w8Zy4MjxC9Hqhyv7rhOMzSf_t1ZqWnyXW=9Q7iJg@mail.gmail.com>

On 26-03-20, 23:08, Linus Walleij wrote:
> On Wed, Mar 25, 2020 at 5:28 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Mon, Mar 2, 2020 at 5:22 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> 
> > > FWIW, I have tried something similar for arm64 earlier.
> > >
> > > https://lore.kernel.org/lkml/af12e002bc165844101830c0eb00e283b536a879.1510813288.git.viresh.kumar@linaro.org/
> >
> > I've dropped this one and not applied it for now after rereading the old thread.
> > If there is a broader agreement on what the default should be, please
> > collect more Acks and we can apply whatever you come up with.
> 
> I think there is a more compelling argument: if I understand correctly
> the energy aware scheduling and HMP on big.LITTLE only works
> correctly if schedutil is used as cpufreq governor (correct Vincent, Viresh?)
> 
> That would make the default multi_v7 unusable (or misbehaving)
> on e.g. Vexpress TC2.
> 
> Thus I suspect the Vexpress and other machines using HMP
> and big.LITTLE should just select
> CPU_FREQ_DEFAULT_GOV_SCHEDUTIL in their Kconfig.
> 
> That will of course make it percolate up to multi_v7 by default
> as well.
> 
> If more magic configs are necessary to select to make a TC2
> work properly I'd like to know these as well so we can just select
> them all by default also for these targets.

I always agreed that schedutil must be selected as default governor
instead of ondemand and I still want to get my arm64 patch merged :)

And yes, schedutil will work the best for big LITTLE stuff.

-- 
viresh

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Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-29 21:02 Linus Walleij
2020-03-02  4:22 ` Viresh Kumar
2020-03-25 16:27   ` Arnd Bergmann
2020-03-26 22:08     ` Linus Walleij
2020-03-27  5:07       ` Viresh Kumar [this message]
2020-03-27  8:06       ` Vincent Guittot

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