alt Hacker News> I feel like using spinlocks in user space at all without kernel support like rseq is just asking for weird performance degradations.
Yeah, exactly. "Doctor, help, somebody replaced my wooden hammer with a metal one, and now I can't hit myself in the face with it as many times."
If you use spinlocks in userspace, you're gonna have a bad time.
Most people looking for performance will reach for the spinlock.
The expectation is that the kernel should somehow detect applications that are spinning, and avoid preempting them early.