On 12/24/25 12:18, ALOK TIWARI wrote:

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.

Hi Alok, indeed it was missed, sorry! The cpuidle sysfs dumps pre and post test would be interesting like so: cat /sys/devices/system/cpu/cpu*/cpuidle/state*/* for both would be helpful so I can see what actually changed. Or a trace with cpu_idle events. Additionally a latency distribution of the IO requests would be helpful to relate them to the cpuidle wakeups.

Thanks, Christian