scx/scheds/rust/scx_layered
Tejun Heo 761ec142ce Bump most versions to 1.0.0
sched_ext is about to be merged upstream. There are some compatibility
breaking changes and we're making the current sched_ext/for-6.11
1edab907b57d ("sched_ext/scx_qmap: Pick idle CPU for direct dispatch on
!wakeup enqueues") the baseline.

Tag everything except scx_mitosis as 1.0.0. As scx_mitosis is still in early
development and is currently temporarily disabled, only the patchlevel is
bumped.
2024-07-12 11:34:14 -10:00
..
src Sync from kernel - 1edab907b57d 2024-07-12 11:08:41 -10:00
.gitignore Restructure scheds folder names 2023-12-17 13:14:31 -08:00
build.rs Restructure scheds folder names 2023-12-17 13:14:31 -08:00
Cargo.toml Bump most versions to 1.0.0 2024-07-12 11:34:14 -10:00
LICENSE Restructure scheds folder names 2023-12-17 13:14:31 -08:00
meson.build meson: introduce serialize build option 2024-06-28 10:17:37 +02:00
README.md Add README files for each rust scheduler 2024-01-04 07:35:44 -08:00
rustfmt.toml Restructure scheds folder names 2023-12-17 13:14:31 -08:00

scx_layered

This is a single user-defined scheduler used within sched_ext, which is a Linux kernel feature which enables implementing kernel thread schedulers in BPF and dynamically loading them. Read more about sched_ext.

Overview

A highly configurable multi-layer BPF / user space hybrid scheduler.

scx_layered allows the user to classify tasks into multiple layers, and apply different scheduling policies to those layers. For example, a layer could be created of all tasks that are part of the user.slice cgroup slice, and a policy could be specified that ensures that the layer is given at least 80% CPU utilization for some subset of CPUs on the system.

How To Install

Available as a Rust crate: cargo add scx_layered

Typical Use Case

scx_layered is designed to be highly customizable, and can be targeted for specific applications. For example, if you had a high-priority service that required priority access to all but 1 physical core to ensure acceptable p99 latencies, you could specify that the service would get priority access to all but 1 core on the system. If that service ends up not utilizing all of those cores, they could be used by other layers until they're needed.

Production Ready?

Yes. If tuned correctly, scx_layered should be performant across various CPU architectures and workloads.

That said, you may run into an issue with infeasible weights, where a task with a very high weight may cause the scheduler to incorrectly leave cores idle because it thinks they're necessary to accommodate the compute for a single task. This can also happen in CFS, and should soon be addressed for scx_layered.