Linux Schedutil Governor's Quirky Behavior Persists In 2023

As was immediately visible when firing up the video encoder benchmarks, when switching to the ondemand governor rather than the default schedutil was of immediate benefit to the Threadripper 3990X. The HEVC/H.265 encode performance improved by 9% while not quite as fast as the performance governor, but much closer than where it's found by default with Schedutil. These new numbers are still behind the 2020 state that may be due to the GCC compiler difference or other factors.

Somewhat entertainingly, the schedutil default led to the highest overall power consumption for this test as shown by the PowerCap sysfs interface... On average using Schedutil led to a 158 Watt average compared to a 150 Watt average with the performance governor or 155 Watts with ondemand. The peak power draw of the 3990X was unchanged between governors.

So on a performance-per-Watt basis, the performance governor yielded the best efficiency followed by ondemand and then the default schedutil.

SVT-VP9 was a similar story with a 9% increase to performance when switching from schedutil to the prior Ubuntu default of ondemand, helping close the gap of where it was in 2020.

For SVT-VP9 the CPU power consumption was slightly higher with the performance and ondemand governors but when factoring in the performance-per-Watt it exceeded Schedutil.

The switch from ondemand to schedutil as the default governor on recent Ubuntu Linux releases is the leading contributor to the degraded performance in the video encoding benchmarks compared to the 2020 performance levels.