linux-kernel - Re: stable: commit "cpuidle: menu: Avoid discarding useful information" causes regressions

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Message-ID: <CAJZ5v0j0ykSYrgPKxPHuNS63cD9mUx57qr7axKfhvtmv=sA_VA@mail.gmail.com>
Date: Thu, 16 Oct 2025 11:50:23 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Doug Smythies <dsmythies@...us.net>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Christian Loehle <christian.loehle@....com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>, Sasha Levin <sashal@...nel.org>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Tomasz Figa <tfiga@...omium.org>, stable@...r.kernel.org
Subject: Re: stable: commit "cpuidle: menu: Avoid discarding useful
 information" causes regressions

On Wed, Oct 15, 2025 at 4:32 PM Doug Smythies <dsmythies@...us.net> wrote:
>
> On 2025.10.14 04:50 Rafael J. Wysocki wrote:
> > On Wed, Oct 15, 2025 at 5:41 AM Doug Smythies <dsmythies@...us.net> wrote:
> >>
> >> On 2025.10.14 18:30 Sergey Senozhatsky wrote:
> >>> On (25/10/14 17:54), Rafael J. Wysocki wrote:
> >>>> Sergey, can you please run the workload under turbostat on the base
> >>>> 6.1.y and on 6.1.y with the problematic commit reverted and send the
> >>>> turbostat output from both runs (note: turbostat needs to be run as
> >>>> root)?
> >>>
> >>> Please find attached the turbostat logs for both cases.
> >>
> >> The turbostat data suggests that power limit throttling is involved.
> >
> > Why do you think so?
>
> I observed sustained processor package powers over the PL1 limit of 6 watts,
> combined with increased busy % while at the same time power and CPU frequency going down.
> I admit the time constant of 28 seconds only seems to be exceeded once.

I see, thanks!

> Since I seem to be unable to function without making a graph, some are attached,
> including Idle state usage, which might be useful for your other email.

Thanks for the graphs, they are useful.

> (The graphs are poorly labelled and such.)

No worries.