Linux 6.8 To Drop SLAB While Delivering A SLUB Optimization: 34% Micro-Benchmark Win

Ahead of the Linux 6.7 stable kernel release expected on Sunday, some early pull requests have already begun trickling in for the Linux 6.8 merge window to follow. The SLAB updates were sent to Linus Torvalds on Friday in preparing for this next kernel cycle.

As previously mentioned on Phoronix, following the SLAB allocator being deprecated in the Linux 6.5 kernel, Linux 6.8 will now go ahead and remove the SLAB code. That follows SLOB previously going through its deprecation and removal with the kernel now just focusing on SLUB as the preferred allocator.

Linux 6.8 is dropping SLAB and will allow for lower code maintenance and better optimizations/improvements moving forward for SLUB with less technical debt around maintaining multiple allocators. SUSE's Vlastimil Babka wrote in the Linux 6.8 SLAB updates pull request:

"Removing the choice of allocators has already allowed to simplify and optimize the code wiring up the kmalloc APIs to the SLUB implementation."

The 6.8 pull request also includes a SLUB improvement for delayed freezing of CPU partial slabs. This improvement yielded a 34% improvement for a stress-ng micro-benchmark.