linux-kernel - Re: [PATCH v6 2/2] thermal/debugfs: Add thermal debugfs information for mitigation episodes

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Date: Tue, 9 Jan 2024 14:02:44 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: rjw@...ysocki.net, lukasz.luba@....com, rui.zhang@...el.com, 
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v6 2/2] thermal/debugfs: Add thermal debugfs information
 for mitigation episodes

On Tue, Jan 9, 2024 at 10:41 AM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> The mitigation episodes are recorded. A mitigation episode happens
> when the first trip point is crossed the way up and then the way
> down. During this episode other trip points can be crossed also and
> are accounted for this mitigation episode. The interesting information
> is the average temperature at the trip point, the undershot and the
> overshot. The standard deviation of the mitigated temperature will be
> added later.
>
> The thermal debugfs directory structure tries to stay consistent with
> the sysfs one but in a very simplified way:
>
> thermal/
>  `-- thermal_zones
>      |-- 0
>      |   `-- mitigations
>      `-- 1
>          `-- mitigations
>
> The content of the mitigations file has the following format:
>
> ,-Mitigation at 349988258us, duration=130136ms
> | trip |     type | temp(°mC) | hyst(°mC) |  duration  |  avg(°mC) |  min(°mC) |  max(°mC) |
> |    0 |  passive |     65000 |      2000 |     130136 |     68227 |     62500 |     75625 |
> |    1 |  passive |     75000 |      2000 |     104209 |     74857 |     71666 |     77500 |
> ,-Mitigation at 272451637us, duration=75000ms
> | trip |     type | temp(°mC) | hyst(°mC) |  duration  |  avg(°mC) |  min(°mC) |  max(°mC) |
> |    0 |  passive |     65000 |      2000 |      75000 |     68561 |     62500 |     75000 |
> |    1 |  passive |     75000 |      2000 |      60714 |     74820 |     70555 |     77500 |
> ,-Mitigation at 238184119us, duration=27316ms
> | trip |     type | temp(°mC) | hyst(°mC) |  duration  |  avg(°mC) |  min(°mC) |  max(°mC) |
> |    0 |  passive |     65000 |      2000 |      27316 |     73377 |     62500 |     75000 |
> |    1 |  passive |     75000 |      2000 |      19468 |     75284 |     69444 |     77500 |
> ,-Mitigation at 39863713us, duration=136196ms
> | trip |     type | temp(°mC) | hyst(°mC) |  duration  |  avg(°mC) |  min(°mC) |  max(°mC) |
> |    0 |  passive |     65000 |      2000 |     136196 |     73922 |     62500 |     75000 |
> |    1 |  passive |     75000 |      2000 |      91721 |     74386 |     69444 |     78125 |
>
> More information for a better understanding of the thermal behavior
> will be added after. The idea is to give detailed statistics
> information about the undershots and overshots, the temperature speed,
> etc... As all the information in a single file is too much, the idea
> would be to create a directory named with the mitigation timestamp
> where all data could be added.
>
> Please note this code is immune against trip ordering but not against
> a trip temperature change while a mitigation is happening. However,
> this situation should be extremely rare, perhaps not happening and we
> might question ourselves if something should be done in the core
> framework for other components first.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>

Both patches in the series look good to me now, so I'll queue them up
for 6.8-rc1.

Thanks!