[NEWS] SLUB Adapted To Be Real-Time Linux Compatible (PREEMPT_RT)

[audiojunkie]

New news about the real-time kernel patches upstreaming (to the mainline kernel) that is going on:


https://www.phoronix.com/scan.php?pa...-RT-Compatible

Written by Michael Larabel in Linux Kernel on 9 September 2021 at 12:00 AM EDT. 3 Comments

LINUX KERNEL -- One of the nice low-level improvements we've seen with Linux 5.15 is a number of pieces falling into place in the quest of upstreaming the real-time (RT) patches for Linux. The latest merge makes SLUB RT-compatible.

The big RT addition for Linux 5.15 was the PREEMPT_RT locking code being merged and that representing a bulk of the previously outstanding real-time patches needing to be upstreamed. That is a big milestone albeit not across the finish line yet and more of the kernel code continues to be adapted to make it compatible with RT configurations.

Linux's SLUB memory management code on Wednesday saw RT support merged. The SLUB allocation code is now considered "fully PREEMPT_RT compatible" and so far has been found to not introduce any performance regressions for RT or non-RT kernel configurations -- besides the expected RT tradeoff of some throughput regressions due to preemption improvements through the RT mutex.

The merge comment notes, "This series was initially inspired by Mel's pcplist local_lock rewrite, and also interest to better understand SLUB's locking and the new primitives and RT variants and implications. It makes SLUB compatible with PREEMPT_RT and generally more preemption-friendly, apparently without significant regressions, as the fast paths are not affected."

More details on the SLUB changes for Linux 5.15 via the merge.

[Fergler]

For us laymen, what does this mean for audio?

[audiojunkie]

Originally Posted by Fergler

For us laymen, what does this mean for audio?

For best results, Audio recording should use low latency. To have low latency audio in linux, you need a specially tuned kernel. For 20 years, there has been a series of low latency kernel patches that have been kept updated, but outside of the mainline kernel. Over the years, work has gone on to incorporate those patches into the mainline kernel. The goal is to remove the need for custom kernels—to make it easier for people to have low latency audio on linux without needing to have a custom kernel compiled. This article is reporting that more progress is being made in this goal. 🙂