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

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Message-ID: <c44a14db-28b6-41f3-984b-bfe67fecfa66@oracle.com>
Date: Wed, 24 Dec 2025 17:48:03 +0530
From: ALOK TIWARI <alok.a.tiwari@...cle.com>
To: christian.loehle@....com, rafael.j.wysocki@...el.com,
        daniel.lezcano@...aro.org
Cc: gregkh@...uxfoundation.org, sashal@...nel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [report] Performance regressions introduced via "cpuidle: menu:
 Remove iowait influence" on 6.12.y

Hi Christian,


On 12/3/2025 11:01 PM, ALOK TIWARI wrote:
> 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
> 

Just a gentle ping in case this was missed.
Please let us know if we are missing anything or if there are additional 
things to consider.

Thanks,
Alok