Linux Schedutil Governor's Quirky Behavior Persists In 2023
Outside of the Scalable Video Technology (SVT) encoders, the x265 performance drop was lessened by switching back to the ondemand governor on Ubuntu 23.04 for this Threadripper 3990X system.
The CPU power consumption of the Threadripper 3990X was only slightly higher when using the optimal "performance" governor for x265.
For the regressed workloads compared to Ubuntu 20.04 LTS on the Threadripper 3990X, one of the main contributors was the default change from ondemand to schedutil for the ACPI CPUFreq driver. Schedutil overall is comparable to ondemand but for both Intel and AMD processors over the years I've commonly seen situations like this where the performance is negatively impacted.
Personally, it would be nice if Ubuntu Linux on desktop/server class hardware would simply default to the performance governor as is done on the likes of RHEL/CentOS and Clear Linux among others...
The performance governor on the Threadripper 3990X while running the video encode benchmarks actually had comparable power use to ondemand and in turn was lower overall on average than the acpi-cpufreq schedutil configuration used by default.
So for those wondering about the video encode results from the recent 3 year Threadripper comparison, here is your reminder of the quirky Schedutil default.
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