> unless it has enough other things to do to to keep every core busy. And in this all-cores-busy case, do you want your waiters burning one of those precious c

> unless it has enough other things to do to to keep every core busy. And in this all-cores-busy case, do you want your waiters burning one of those precious cores while lock holders are preempted? If you care enough about your system design to even affirmatively select spinlocks in the first place, you should probably also care enough to not use them in preemptible userspace. Or at least, I am not aware of any reasonable usecase. Hybrid sleeplocks are fine, of course.