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From:   Valentin Schneider <valentin.schneider@arm.com>
To:     Thara Gopinath <thara.gopinath@linaro.org>
Cc:     Russell King - ARM Linux admin <linux@armlinux.org.uk>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: v5.7: new core kernel option missing help text
Message-ID: <jhjeeqvi3m1.mognet@arm.com>
In-reply-to: <a34fcb9a-ba4b-0c9e-328f-1244c2720ed2@linaro.org>
Date:   Thu, 04 Jun 2020 10:26:27 +0100
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On 04/06/20 01:48, Thara Gopinath wrote:
> Hi Russel/Valentin
>
> The feature itself like Valentin explained below allows scheduler to be
> aware of cpu capacity reduced due to thermal throttling.
> arch_set_thermal_pressure feeds the capped capacity to the scheduler and
> hence the feature makes sense only if arch_set_thermal_pressure is
> implemented. Having said that arch_set_thermal_pressure is implemented
> in arch_topology driver for arm and arm64 platforms. But the feature
> itself is not bound to arm/arm64 platforms. So it would make it wrong to
> add a "depends on (ARM || ARM64) option."
>
> I agree with Vincent that allowing user to choose this option is
> probably not the best. IMO, this should be enabled by default in arm64
> defconfig considering both GENERIC_ARCH_TOPOLOGY and CPU_FREQ_THERMAL
> are enabled by default.

Right, I had skimmed over that but it probably does make more sense not
to bother users with it.

> So if it is acceptable three things to be done are:
> 1. Add the help text.
> 2. Don't allow SCHED_THERMAL_PRESSURE configurable by user
> 3. Enable it by default in arm64 defconfig

... and arm as well, I suppose?