Reading /proc/filesystems Is Surprisingly Done Very Often & Now As Much As 444% Faster

The Linux 7.2 kernel includes a significant optimization for /proc/filesystems, delivering up to 444% faster reads. The improvement was motivated by the surprising frequency with which this file is accessed — primarily because libselinux reads it and is linked into many common programs, including sed. The optimization involves pre-generating and caching the /proc/filesystems string, RCU-ifying the filesystem list to eliminate reference counting overhead on open/close, and cleaning up a hand-rolled linked list. The change was authored by Christian Brauner and merged by Linus Torvalds.