The [1]sched_ext code for extensible scheduler support and being able to quickly prototype new Linux kernel scheduling improvements continues evolving nicely since its much anticipated merging to the mainline kernel in 2024. Ahead of the imminent Linux 6.15 merge window, the sched_ext feature updates were sent out today for this next kernel cycle.

The sched_ext code continues seeing new work to enhance its flexibility across different hardware designs, such as with Linux 6.15 being able to selectively toggle ttwu_queue. The default idle CPU selection logic has also been improved and other enhancements made.

The sched_ext [2]pull request for the Linux 6.15 merge window sums up the highlights as:

"- Add mechanism to count and report internal events. This significantly improves visibility on subtle corner conditions.

- The default idle CPU selection logic is revamped and improved in multiple ways including being made topology aware.

- sched_ext was disabling ttwu_queue for simplicity, which can be costly when hardware topology is more complex. Implement SCX_OPS_ALLOWED_QUEUED_WAKEUP so that BPF schedulers can selectively enable ttwu_queue.

- tools/sched_ext updates to improve compatibility among others.

- Other misc updates and fixes."



[1] https://www.phoronix.com/search/sched_ext

[2] https://lore.kernel.org/lkml/Z999bMA5tftvV28a@slm.duckdns.org/