Linux 5.3 Picks Up Utilization Clamping - Ensuring GUI Threads Get Maximum Frequency

The scheduler changes for the Linux 5.3 kernel are as busy as ever.

One of the most interesting scheduler changes for Linux 5.3 was made by Arm's Patrick Bellasi. The addition is introducing utilization clamping support as an extension of their work on the Energy Aware Scheduling framework in order to boost some workloads while capping background workloads. Energy Aware Scheduling factors in the CPU topology of modern hardware -- particularly Arm big.LITTLE designs -- with differing power and performance characteristics in order to better schedule what CPU cores should be used for a given workload.

With this new utilization clamping support, the aim is to ensure GUI threads get a high performance core / maximum frequency while background processing tasks would be shifted to the lower-power/performance cores. As part of the utilization clamping are new controls via sysfs for adjusting the "uclamp" behavior.

The scheduler changes for Linux 5.3 also contain other optimizations and fixes throughout.