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37 lines
1.8 KiB
Markdown
37 lines
1.8 KiB
Markdown
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# scx_rusty
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This is a single user-defined scheduler used within [sched_ext](https://github.com/sched-ext/scx/tree/main), which is a Linux kernel feature which enables implementing kernel thread schedulers in BPF and dynamically loading them. [Read more about sched_ext](https://github.com/sched-ext/scx/tree/main).
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## Overview
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A multi-domain, BPF / user space hybrid scheduler. The BPF portion of the
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scheduler does a simple round robin in each domain, and the user space portion
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(written in Rust) calculates the load factor of each domain, and informs BPF of
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how tasks should be load balanced accordingly.
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## How To Install
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Available as a [Rust crate](https://crates.io/crates/scx_rusty): `cargo add scx_rusty`
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## Typical Use Case
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Rusty is designed to be flexible, and accommodate different architectures and
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workloads. Various load balancing thresholds (e.g. greediness, frequenty, etc),
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as well as how Rusty should partition the system into scheduling domains, can
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be tuned to achieve the optimal configuration for any given system or workload.
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## Production Ready?
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Yes. If tuned correctly, rusty should be performant across various CPU
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architectures and workloads. Rusty by default creates a separate scheduling
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domain per-LLC, so its default configuration may be performant as well. Note
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however that scx_rusty does not yet disambiguate between LLCs in different NUMA
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nodes, so it may perform better on multi-CCX machines where all the LLCs share
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the same socket, as opposed to multi-socket machines.
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Note as well that you may run into an issue with infeasible weights, where a
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task with a very high weight may cause the scheduler to incorrectly leave cores
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idle because it thinks they're necessary to accommodate the compute for a
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single task. This can also happen in CFS, and should soon be addressed for
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scx_rusty.
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