linux-kernel - [report] Performance regressions introduced via "cpuidle: menu: Remove iowait influence" on 6.12.y

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Message-ID: <c0b5c308-ea18-4736-b507-01cb06cb8dfc@oracle.com>
Date: Wed, 3 Dec 2025 23:01:13 +0530
From: ALOK TIWARI <alok.a.tiwari@...cle.com>
To: christian.loehle@....com, rafael.j.wysocki@...el.com,
        daniel.lezcano@...aro.org, linux-pm@...r.kernel.org
Cc: gregkh@...uxfoundation.org, sashal@...nel.org,
        linux-kernel@...r.kernel.org,
        "stable@...r.kernel.org"
 <stable@...r.kernel.org>
Subject: [report] Performance regressions introduced via "cpuidle: menu:
 Remove iowait influence" on 6.12.y

Hi,

I’m reporting a performance regression of up to 6% sequential I/O
vdbench regression observed on 6.12.y kernel.
While running performance benchmarks on v6.12.60 kernel the sequential 
I/O vdbench metrics are showing a 5-6% performance regression when 
compared to v6.12.48

Bisect root cause commit
========================
- commit b39b62075ab4 ("cpuidle: menu: Remove iowait influence")

Things work fine again when the previously removed 
performance-multiplier code is added back.

Test details
============
The system is connected to a number of disks in disk array using 
multipathing and directio configuration in the vdbench profile.

wd=wd1,sd=sd*,rdpct=0,seekpct=sequential,xfersize=128k
rd=128k64T,wd=wd1,iorate=max,elapsed=600,interval=1,warmup=300,threads=64

Thanks,
Alok