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

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Message-ID: <002001dc3de0$9119d470$b34d7d50$@telus.net>
Date: Wed, 15 Oct 2025 07:32:42 -0700
From: "Doug Smythies" <dsmythies@...us.net>
To: "'Rafael J. Wysocki'" <rafael@...nel.org>
Cc: "'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>,
	"Doug Smythies" <dsmythies@...us.net>
Subject: RE: stable: commit "cpuidle: menu: Avoid discarding useful information" causes regressions

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.

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.
(The graphs are poorly labelled and such.)

... Doug


Download attachment "idle-states.png" of type "image/png" (273242 bytes)

Download attachment "mhz.png" of type "image/png" (79930 bytes)

Download attachment "pkg-pwr.png" of type "image/png" (56278 bytes)

Download attachment "temp.png" of type "image/png" (48797 bytes)