Z3fold Allocator Slated For Removal From The Linux Kernel

Written by Michael Larabel in Linux Kernel on 28 January 2025 at 06:15 AM EST. 39 Comments
LINUX KERNEL
The Z3fold allocator for compressed pages was quietly deprecated several months ago with users encouraged to use zsmalloc instead. With no one vocally objecting, the Z3fold allocator code is now being positioned for removal from the Linux kernel source tree.

Z3fold is an allocator for compressed pages whereby you can achieve up to three compressed pages per physical page. Moving forward users are encouraged to use the Zsmalloc allocator. The main downside with zsmalloc is requiring an MMU whereas Z3fold can get by without a memory management unit. Zsmalloc used to have worse latency than Z3fold but that's been found to no longer be the case. Z3fold on the other hand has been found to contain some latent bugs and can have higher swap use than zsmalloc.

Z3fold Kconfig


With Z3fold having been deprecated for two kernel cycles without complaint, there are now patches pending to remove the Z3fold from the Linux kernel.

This patch goes ahead and carries out that removal. The Zbud deprecation/removal is also expected to happen coming soon as it offers only small latency gains but with much memory waste over Zsmalloc. If no objections are raised, this patch removing Z3fold could potentially land for the Linux v6.15 kernel in the spring.
Related News
About The Author
Michael Larabel

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

Popular News This Week