It's common in high performance code to use spin locks (also called busy waiting) to reduce latency. In some circumstances it's better to do nothing and be avai

It's common in high performance code to use spin locks (also called busy waiting) to reduce latency. In some circumstances it's better to do nothing and be available almost immediately to do some work than to naively context switch away and pay the penalty of context switching back later. Check out how futexes are implemented in Linux for an example - hybrid mutex and spin lock.