linux-kernel - Re: [PATCH v1 0/3] thermal/debugfs: Fix and clean up trip point statistics updates

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Date: Mon, 22 Apr 2024 16:20:11 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lukasz Luba <lukasz.luba@....com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, LKML <linux-kernel@...r.kernel.org>, 
	Linux PM <linux-pm@...r.kernel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [PATCH v1 0/3] thermal/debugfs: Fix and clean up trip point
 statistics updates

Hi Lukasz,

On Mon, Apr 22, 2024 at 1:37 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> Hi Rafael,
>
> On 4/17/24 14:07, Rafael J. Wysocki wrote:
> > Hi Everyone,
> >
> > The first patch in this series addresses the problem of updating trip
> > point statistics prematurely for trip points that have just been
> > crossed on the way down (please see the patch changelog for details).
> >
> > The way it does that renders the following cleanup patch inapplicable:
> >
> > https://lore.kernel.org/linux-pm/2321994.ElGaqSPkdT@kreacher/
> >
> > The remaining two patches in the series are cleanups on top of the
> > first one.
> >
> > This series is based on an older patch series posted last week:
> >
> > https://lore.kernel.org/linux-pm/13515747.uLZWGnKmhe@kreacher/
> >
> > but it can be trivially rebased on top of the current linux-next.
> >
> > Thanks!
> >
> >
> >
>
> I've checked this patch patch set on top of your bleeding-edge
> which has thermal re-work as well. The patch set looks good
> and works properly.
>
> Although, I have found some issue in this debug info files and
> I'm not sure if this is expected or not. If not I can address this
> and send some small fix for it.
>
> When I read the cooling device residency statistics, I don't
> get updates for the first time the state is used. It can only
> be counted when that state was known and finished it's usage.
>
> IMO it is not the right behavior, isn't it?

I agree, it is not.

> Experiment:
> My trip points are 70degC and 75degC and I'm setting emulated
> temperature to cross them and get cooling states 1 then 0.
> As you can see the statistics counter only starts showing value after
> after trip crossing down.
> ------------------------------------8<-----------------------------------
>
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> root@arm:~#
> root@arm:~#
> root@arm:~# echo 71000 > /sys/class/thermal/thermal_zone0/emul_temp
>
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> root@arm:~# echo 76000 > /sys/class/thermal/thermal_zone0/emul_temp
>
> root@arm:~#
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       518197
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       518197
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       518197
> root@arm:~# echo 71000 > /sys/class/thermal/thermal_zone0/emul_temp
>
> root@arm:~#
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       520066
> 1       17567
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       522653
> 1       17567
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       526151
> 1       17567
> root@arm:~# echo 66000 > /sys/class/thermal/thermal_zone0/emul_temp
>
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       537366
> 1       17567
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       544936
> 1       17567
> root@arm:~# cat
> /sys/kernel/debug/thermal/cooling_devices/0/time_in_state_ms
> State   Residency
> 0       556694
> 1       17567
> root@arm:~#
>
> ------------------------------->8----------------------------------------
>
> Please let me know what do you think about that behavior.

If you have thought about fixing it already, please do so.

Thanks!