PREEMPT_RT

PREEMPT_RT was a set of patches for the Linux kernel which implement both hard and soft real-time computing capabilities.^[1] On September 20, 2024, PREEMPT_RT was fully merged and enabled in mainline Linux on the supported architectures x86, x86_64, RISC-V and ARM64.^[2] This will make kernel v6.12 the first release to include baked-in real-time capability. Support for LoongArch is added in v6.13.^[3]

History

The PREEMPT_RT patchset has been in development since 2005.^[4] In 2021, the preemption core locking code was merged.^[5]^[6]

Since February 2023, Canonical has been releasing real-time versions of Ubuntu Pro, free for personal and small-scale commercial use in up to 5 machines.^[7]^[8] The real-time kernel can be added to various existing Ubuntu releases through an enablement process.^[8] These kernels include the PREEMPT_RT patchset and offer long-term support.^[8]

MontaVista Software has been releasing a real-time Linux distribution containing the PREEMPT_RT patchset since the early 2000. Montavista's current main embedded Linux product, CGX, contains real-time preemption as a standard feature.

At the Sep. 2024 European Open Source Summit, Linus Torvalds announced that PREEMPT_RT had been accepted into the mainline linux kernel after a protracted development hurdle involving the printk kernel logging facility.

References

^ "20 years later, real-time Linux makes it to the kernel - really". zdnet.com. Retrieved 2024-09-19.
^ "Merge tag 'sched-rt-2024-09-17' - kernel/git/torvalds/linux.git - Linux kernel source tree". git.kernel.org. Retrieved 2024-09-20.
^ GIT PULL: LoongArch changes for v6.13
^ Reghenzani, Federico; Massari, Giuseppe; Fornaciari, William (2019-02-21). "The Real-Time Linux Kernel: A Survey on PREEMPT_RT". ACM Computing Surveys. 52 (1): 18:1–18:36. doi:10.1145/3297714. hdl:11311/1076057. ISSN 0360-0300.
^ "Realtime preemption locking core merged [LWN.net]". lwn.net. Retrieved 2023-02-09.
^ "The future of realtime Linux". LWN.net. Retrieved 2023-02-09.
^ Proven, Liam. "Real-time Ubuntu 22.04: What you need to know". The Register. Retrieved 2023-02-20.
^ ^a ^b ^c "Canonical releases Real-time Ubuntu 24.04 LTS". Ubuntu. Retrieved 2024-07-03.

External links

Official website

[1] "20 years later, real-time Linux makes it to the kernel - really". zdnet.com. Retrieved 2024-09-19.

[2] "Merge tag 'sched-rt-2024-09-17' - kernel/git/torvalds/linux.git - Linux kernel source tree". git.kernel.org. Retrieved 2024-09-20.

[3] GIT PULL: LoongArch changes for v6.13

[4] Reghenzani, Federico; Massari, Giuseppe; Fornaciari, William (2019-02-21). "The Real-Time Linux Kernel: A Survey on PREEMPT_RT". ACM Computing Surveys. 52 (1): 18:1–18:36. doi:10.1145/3297714. hdl:11311/1076057. ISSN 0360-0300.

[5] "Realtime preemption locking core merged [LWN.net]". lwn.net. Retrieved 2023-02-09.

[6] "The future of realtime Linux". LWN.net. Retrieved 2023-02-09.

[7] Proven, Liam. "Real-time Ubuntu 22.04: What you need to know". The Register. Retrieved 2023-02-20.

[:1-8] "Canonical releases Real-time Ubuntu 24.04 LTS". Ubuntu. Retrieved 2024-07-03.

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