Linux 7.3 Scheduler Enhancements: Assist For Gaming, Hybrid CPUs, Decrease Scheduler Latency

The thrilling set of scheduler updates have been merged for the Linux 7.3 merge window.

First up, the scheduler merge comprises the work to assist increase gaming efficiency on previous “potato” {hardware}. That patch sequence from Intel engineer Peter Zijlstra helps with cgroup scheduling and was proven to be useful for testing on an Intel Sandy Bridge CPU with AMD Radeon RX 580 Polaris graphics. This “flatten the pick” patch sequence exhibits some very promising outcomes:

The work was summed up within the pull request as:

“Series to ‘flatten the pick’: improve cgroup scheduling, which has always been problematic and painful, which has caused various scheduling misbehavior such as the mishandling of reniced tasks et al. Add various cgroup weight distribution methods via cgroup_mode: ‘up’, ‘max’, ‘concur’ and ‘tasks’ – with the default being ‘concur’ which is the most precise yet also most expensive version. Finally, change cgroup scheduling to a single runqueue.”

Separately, the scheduler code makes enhancements to decrease the scheduling latency of short-slice duties. Vincent Guittot confirmed off some very important enhancements in cyclictest from this work:

The scheduler updates additionally embrace an essential repair to cluster scheduling for CPUs with uneven capability, a.ok.a. Intel hybrid CPUs. That work was beforehand talked about on Phoronix inside Linux 7.3 To Better Handle Cluster Load Balancing On Intel Hybrid CPUs.

Additionally, to assist with load-balancing, Linux 7.3 now prefers totally idle cores for NOHZ balancing. There can be quite a lot of different code updates discovered with the scheduler adjustments merged by way of this pull request.