Can a Rust-Based Linux Scheduler Outperform the Default C Scheduler?

Recently, Ubuntu kernel engineer Andrea Righi experimented with a Rust‑implemented Linux scheduler during the Christmas holidays. Using the sched_ext interface and eBPF, he created a runtime‑loadable scheduler that showed surprising performance.

1. Unexpected Results: Rust Beats the Default

Righi reported that the Rust scheduler not only worked correctly but also outperformed the default C‑based EEVDF scheduler in certain workloads, such as the game Terraria . While the kernel build time increased from 280 s to 361 s (about 30% longer), the game frame rate doubled from ~30 fps to ~60 fps.

The code has been published on GitHub for further exploration.

2. The Scheduler Debate: Does Linux Need More?

Linux’s core scheduler, based on the Completely Fair Scheduler (CFS), aims to allocate CPU time fairly among processes. As heterogeneous and distributed workloads grow, there is increasing interest in more flexible, extensible scheduling mechanisms.

BPF (Berkeley Packet Filter) provides a way to run custom code in response to kernel events without recompiling the kernel. Since its 2014 integration as eBPF, it has become a general‑purpose execution engine for tasks such as performance analysis.

Industry voices, including LWN editor Jonathan Corbett, argue that bringing BPF into the CPU scheduler is inevitable, enabling domain‑specific schedulers for gaming, networking, and other workloads.

Righi’s scx_rustland leverages sched_ext, an experimental feature that allows BPF‑based schedulers to be loaded at runtime. While some kernel contributors, like Linus Torvalds and maintainer Peter Zijlstra, express skepticism about dynamic schedulers, other companies (e.g., AMD, Google) are exploring alternatives.

3. Rust vs. C: Is There a Real Advantage?

Rust’s growing popularity stems from its memory‑safety guarantees, making it attractive for critical kernel components traditionally written in C. Torvalds has indicated openness to Rust in drivers and subsystems.

Righi noted that Rust enabled rapid development—he could write the scheduler in a few weeks, reusing high‑level abstractions while still accessing low‑level details. Although he does not claim massive performance gains solely from the language, the experiment demonstrates that Rust can produce competitive, even superior, results in specific scenarios.

Reference links: https://www.phoronix.com/news/Rust-Linux-Scheduler-Experiment https://thenewstack.io/bpf-opens-a-door-to-linux-dynamic-scheduling-maybe-with-rust/