Recently, the long-term support (LTS) Linux Kernel 5.10 version has the problem of Btrfs performance regression. In some cases, Btrfs performance will drop sharply by 500% to 2000%.
The developer who submitted this question stated that as a long-term user of Btrfs, he noticed that some daily Linux development tasks became very slow when using the 5.10 kernel, such as decompressing a large .tar.zst file. The decompression time may change from the original About 15 seconds becomes almost 5 minutes.
Btrfs (usually pronounced as Butter FS) is a COW (copy-on-write) file system introduced by Oracle in 2007. The goal is to replace the Linux ext file system. Btrfs added some features not supported by ext3/4, such as writable disk snapshots (snapshots), and support for recursive snapshots (snapshots of snapshots), built-in disk array (RAID) support, and support for the concept of subvolumes , Allowing online adjustment of file system size, etc. At present, Btrfs has replaced ext4 as the default file system in Fedora 33 desktop version , and is widely used in Linux distributions such as SUSE and Ubuntu.
It is reported that the Linux kernel maintainer Josef Bacik has found the root cause of this problem before Christmas, saying that the reason why this problem was missed in the test is "because of doing a lot of research on Btrfs I/O performance in recent weeks. relevant job". They may push the patch to Linux Kernel 5.10 in the near future to solve this problem.
Although it has been born for 13 years, as a relatively new file system, the use of Btrfs has always been questioned in the community. This time the problem undoubtedly pushed the file system to the forefront again. Many users commented under the post that raised the issue, "I have been using Btrfs for many years, and I have been tired of its failure. Recently I rebuilt my file system and re-used ext4."