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

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Date:   Thu, 14 Dec 2023 08:54:10 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     catalin.marinas@....com, bristot@...hat.com,
        linux-pm@...r.kernel.org, juri.lelli@...hat.com, agross@...nel.org,
        viresh.kumar@...aro.org, rafael@...nel.org,
        linux-kernel@...r.kernel.org, rui.zhang@...el.com,
        dietmar.eggemann@....com, mgorman@...e.de,
        linux-trace-kernel@...r.kernel.org, mingo@...hat.com,
        peterz@...radead.org, konrad.dybcio@...aro.org,
        andersson@...nel.org, rostedt@...dmis.org,
        linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, bsegall@...gle.com,
        vschneid@...hat.com, will@...nel.org, sudeep.holla@....com,
        daniel.lezcano@...aro.org, mhiramat@...nel.org,
        amit.kachhap@...il.com
Subject: Re: [PATCH 4/4] sched: Rename arch_update_thermal_pressure into
 arch_update_hw_pressure



On 12/14/23 08:36, Vincent Guittot wrote:
> On Thu, 14 Dec 2023 at 09:30, Lukasz Luba <lukasz.luba@....com> wrote:
>>
>>
>> On 12/12/23 14:27, Vincent Guittot wrote:

[snip]

>>>        update_rq_clock(rq);
>>> -     thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
>>> -     update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure);
>>> +     hw_pressure = arch_scale_hw_pressure(cpu_of(rq));
>>> +     update_hw_load_avg(rq_clock_task(rq), rq, hw_pressure);
>>
>> We switch to task clock here, could you tell me why?
>> Don't we have to maintain the boot command parameter for the shift?
> 
> This should have been part of the patch5 that I finally removed. IMO,
> the additional time shift with rq_clock_thermal is no more needed now
> that we have 2 separates signals
> 

I didn't like the left-shift which causes the signal to converge slowly.
I rather wanted right-shift to converge (react faster), so you have my
vote for this change. Also, I agree that with the two-signal approach
this shift trick can go away now. I just worry about the dropped boot
parameter.

So, are going to send that patach5 which removes the
'sched_thermal_decay_shift' and documentation bit?