Read-Mostly Atomicity

In Chapter  4 we considered the topic of busy-wait mutual exclusion, which achieves atomicity by allowing only one thread at a time to execute a critical section. While mutual exclusion is sufficient to ensure atomicity, it is by no means necessary. Any mechanism that satisfies the ordering constraints of Sec.  3.1.2 will also suffice. In particular, read-mostly optimizations exploit the fact that operations can safely execute concurrently, while still maintaining atomicity, if they read shared data without writing it.