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

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Message-ID: <zfmoe4i3tpz3w4wrduhyxtyxtsdvgydtff3a235owqpzuzjug7@ulxspaydpvgi>
Date: Tue, 14 Oct 2025 16:54:45 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>, 
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>, 
	Christian Loehle <christian.loehle@....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 (25/10/14 09:47), Greg Kroah-Hartman wrote:
> On Tue, Oct 14, 2025 at 04:43:43PM +0900, Sergey Senozhatsky wrote:
> > Hello,
> > 
> > We are observing performance regressions (cpu usage, power
> > consumption, dropped frames in video playback test, etc.)
> > after updating to recent stable kernels.  We tracked it down
> > to commit 3cd2aa93674e in linux-6.1.y and commit 3cd2aa93674
> > in linux-6.6.y ("cpuidle: menu: Avoid discarding useful information",
> > upstream commit 85975daeaa4).
> > 
> > Upstream fixup fa3fa55de0d ("cpuidle: governors: menu: Avoid using
> > invalid recent intervals data") doesn't address the problems we are
> > observing.  Revert seems to be bringing performance metrics back to
> > pre-regression levels.
> > 
> 
> For some reason that commit was not added to the 6.1 releases, sorry
> about that.  Can you submit a working/tested backport so we can queue it
> up after the next round of releases in a few days?

Sorry for the confusion, the commit in question presents both in
stable 6.1 and in 6.6 and appears to be causing regressions on our
tests.  I copy-pasted wrong commit id for 6.1: it should be a9edb700846
for 6.1 (and 3cd2aa93674 for 6.6).