> although strangely it was more expensive on FreeBSD I think mutex ops in 5.3 depended on syscalls or so. I distinctly remember a commit reducing mutex overh

> although strangely it was more expensive on FreeBSD I think mutex ops in 5.3 depended on syscalls or so. I distinctly remember a commit reducing mutex overheads by moving more of it into userspace, somewhat like futex I guess.