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

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Message-ID: <CAJZ5v0ix7zdR0hJqN9OZPGp0oZMD_mzKU48HH1coqHTm7ucTDw@mail.gmail.com>
Date: Wed, 15 Oct 2025 14:31:45 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.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 3:30 AM Sergey Senozhatsky
<senozhatsky@...omium.org> 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.

Thanks!

First off, the CPUiD information reported by turbostat indicates that
the system is a Jasper Lake.  Is this correct?

Second, the overall picture I've got from the turbostat data indicates
that there is a correlation between Bzy_MHz and CPU%c7 (the more time
spent in C7, the higher the average "busy" frequency) which is
generally consistent with the hypothesis that using more C1 causes the
processor to drop the maximum frequency.

Something like this may be induced by RAPL power limits, presumably PL1.

Do you use thermald?