This sounds like premature optimization. FD availability is tracked in a bitmask, and finding the next available slot is a matter of scanning for the first unse

This sounds like premature optimization. FD availability is tracked in a bitmask, and finding the next available slot is a matter of scanning for the first unset bit under a spinlock. This is going to be extremely fast. While you could shard the file descriptor tables for CLONE_FILES processes such as threads, you would likely complicate file descriptor table management and harm the much more important read performance (which is currently just a plain array index and pretty hard to beat). You could also juts create your processes (or threads) without CLONE_FILES so that they get their own file descriptor table. ------ The fdtable can be seen here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/fdtable.h?h=v5.12#n27 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin..., and alloc_fd and __fget can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/file.c?h=v5.12#n470 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin....