When spinning on an atomic operation, you should add some kind of yield operation. The "pause" instruction in x86 at least. On newer CPUs a "monitor" and "mwait

When spinning on an atomic operation, you should add some kind of yield operation. The "pause" instruction in x86 at least. On newer CPUs a "monitor" and "mwait" can work a little better (but may not be available in user space). Do not use thread_yield or other kernel calls, because at that point you're better off using a mutex. When spinning on atomics, the interconnect between cores needs to do a lot of work synchronizing the memory. When adding a pause or monitor instruction, the core will give an opportunity for the other hyperthread in the same core to execute, reducing the amount of churn on the interconnect. Counterintuitively, adding a "pause" in the spin loop will make the program faster by yielding the CPU core for a few nanoseconds.