linux-kernel - Re: stable 6.6: commit "sched/cpufreq: Rework schedutil governor performance estimation' causes a regression

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Message-ID: <s3lyjszylckzg7mfefmysve2tsm53kmorgxly3nln4r6xha264@rct3fyk3d52a>
Date: Fri, 21 Nov 2025 16:02:56 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Christian Loehle <christian.loehle@....com>, 
	Vincent Guittot <vincent.guittot@...aro.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, 
	Viresh Kumar <viresh.kumar@...aro.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Yu-Che Cheng <giver@...gle.com>, Tomasz Figa <tfiga@...omium.org>, stable@...r.kernel.org, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, Lukasz Luba <lukasz.luba@....com>, 
	Dietmar Eggemann <dietmar.eggemann@....com>, Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: stable 6.6: commit "sched/cpufreq: Rework schedutil governor
 performance estimation' causes a regression

On (25/11/21 12:55), Sergey Senozhatsky wrote:
> Hi Christian,
> 
> On (25/11/20 10:15), Christian Loehle wrote:
> > On 11/20/25 04:45, Sergey Senozhatsky wrote:
> > > Hi,
> > > 
> > > We are observing a performance regression on one of our arm64 boards.
> > > We tracked it down to the linux-6.6.y commit ada8d7fa0ad4 ("sched/cpufreq:
> > > Rework schedutil governor performance estimation").
> > > 
> > > UI speedometer benchmark:
> > > w/commit:	395  +/-38
> > > w/o commit:	439  +/-14
> > > 
> > 
> > Hi Sergey,
> > Would be nice to get some details. What board?
> 
> It's an MT8196 chromebook.
> 
> > What do the OPPs look like?
> 
> How do I find that out?
> 
> > Does this system use uclamp during the benchmark? How?
> 
> How do I find that out?
> 
> > Given how large the stddev given by speedometer (version 3?) itself is, can we get the
> > stats of a few runs?
> 
> v2.1
> 
> w/o patch     w/ patch
> 440 +/-30     406 +/-11
> 440 +/-14     413 +/-16
> 444 +/-12     403 +/-14
> 442 +/-12     412 +/-15
> 
> > Maybe traces of cpu_frequency for both w/ and w/o?
> 
> trace-cmd record -e power:cpu_frequency attached.
> 
> "base" is with ada8d7fa0ad4
> "revert" is ada8d7fa0ad4 reverted.

Am getting failed delivery notifications.  I guess attaching those as
text files wasn't a good idea after all.  Vincent, Christian, did you
receive that email?