In FreeBSD the vast majority of sleep lock acquisitions are uncontended and end ...

		cperciva on Sept 2, 2012 \| parent \| context \| favorite \| on: 3.7X speedup from removing a call to sleep In FreeBSD the vast majority of sleep lock acquisitions are uncontended and end up being a single compare-and-exchange -- very fast. Spin locks are slightly more work, since we disable interrupts during them.