linux-kernel - Re: [Patch v5 2/6] sched/fair: Add infrastructure to store and update instantaneous thermal pressure

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Message-ID: <7f93ad5f-cce2-707b-7562-5860bcdd4ae1@arm.com>
Date:   Thu, 7 Nov 2019 12:36:26 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Thara Gopinath <thara.gopinath@...aro.org>,
        Ionela Voinescu <ionela.voinescu@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Quentin Perret <qperret@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Amit Kachhap <amit.kachhap@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [Patch v5 2/6] sched/fair: Add infrastructure to store and update
 instantaneous thermal pressure

On 07/11/2019 11:48, Vincent Guittot wrote:
> On Thu, 7 Nov 2019 at 10:32, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
>>
>> On 06/11/2019 18:53, Thara Gopinath wrote:
>>> On 11/06/2019 07:50 AM, Dietmar Eggemann wrote:
>>>> On 05/11/2019 22:53, Ionela Voinescu wrote:
>>>>> On Tuesday 05 Nov 2019 at 16:29:32 (-0500), Thara Gopinath wrote:
>>>>>> On 11/05/2019 04:15 PM, Ionela Voinescu wrote:
>>>>>>> On Tuesday 05 Nov 2019 at 16:02:00 (-0500), Thara Gopinath wrote:
>>>>>>>> On 11/05/2019 03:21 PM, Ionela Voinescu wrote:

[...]

> In fact, trigger_thermal_pressure_average is only there because of
> shifting the clock which is introduced only in patch 6.
> So remove trigger_thermal_pressure_average from this patch and call directly
> 
> +       update_thermal_load_avg(rq_clock_task(rq), rq,
> +                               per_cpu(thermal_pressure, cpu_of(rq)));
> 
> in patch3

I like the rq_clock_thermal() idea in
https://lore.kernel.org/r/20191107104901.GA472@linaro.org to get rid of
trigger_thermal_pressure_average().

>> That's not the issue here. The issue is the extra shim layer which is
>> unnecessary in the current implementation.
>>
>> update_blocked_averages()
>> {
>>     ...
>>     update_rt_rq_load_avg()
>>     update_dl_rq_load_avg()
>>     update_irq_load_avg()
>>     trigger_thermal_pressure_average() <--- ?
>>     ...
>> }

[...]