linux-kernel - Re: [PATCH v3 4/5] sched: Rename arch_update_thermal_pressure into arch_update_hw

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Message-ID: <0a64731f-f6fa-4382-a5cb-a29061eff2d6@arm.com>
Date: Tue, 9 Jan 2024 12:56:09 +0100
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Vincent Guittot <vincent.guittot@...aro.org>, linux@...linux.org.uk,
 catalin.marinas@....com, will@...nel.org, sudeep.holla@....com,
 rafael@...nel.org, viresh.kumar@...aro.org, agross@...nel.org,
 andersson@...nel.org, konrad.dybcio@...aro.org, mingo@...hat.com,
 peterz@...radead.org, juri.lelli@...hat.com, rostedt@...dmis.org,
 bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com,
 vschneid@...hat.com, lukasz.luba@....com, rui.zhang@...el.com,
 mhiramat@...nel.org, daniel.lezcano@...aro.org, amit.kachhap@...il.com,
 corbet@....net, gregkh@...uxfoundation.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Cc: qyousef@...alina.io
Subject: Re: [PATCH v3 4/5] sched: Rename arch_update_thermal_pressure into
 arch_update_hw_pressure

On 08/01/2024 14:48, Vincent Guittot wrote:
> Now that cpufreq provides a pressure value to the scheduler, rename

I.e. that thermal (e.g. IPA governor) switches from average
(rq->avg_(thermal/hw).load_avg) (1) to instantenous (cpu_pressure) (2).
I rememeber a related dicussion during LPC 2018 :-)

> arch_update_thermal_pressure into HW pressure to reflect that it returns
> a pressure applied by HW (i.e. with a high frequency change) and not
> always related to thermal mitigation but also generated by max current
> limitation as an example. Such high frequency signal needs filtering to be
> smoothed and provide an value that reflects the average available capacity
> into the scheduler time scale.

So 'drivers/cpufreq/qcom-cpufreq-hw.c' is the only user of (1) right
now. Are we expecting more users here? If this stays the only user,
maybe it can do the averages by itself and we can completely switch to (2)?

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