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

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Message-ID: <36iykr223vmcfsoysexug6s274nq2oimcu55ybn6ww4il3g3cv@cohflgdbpnq7>
Date: Tue, 14 Oct 2025 16:43:43 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: 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>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	stable@...r.kernel.org
Subject: stable: commit "cpuidle: menu: Avoid discarding useful information"
 causes regressions

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.