I'm not sure what the author intended, but one way to implement atomics at the microarchitectural level is via a load-linked/store-conditional pair of instructi

I'm not sure what the author intended, but one way to implement atomics at the microarchitectural level is via a load-linked/store-conditional pair of instructions, which often involves tracking the cache line for modification. https://en.wikipedia.org/wiki/Load-link/store-conditional https://en.wikipedia.org/wiki/Load-link/store-conditional It's not "24/7" but it is "watching" in some sense of the word. So not entirely unfair.