Atomic operations are sequences of instructions that guarantee atomic accesses and updates of shared single word variables. This means that atomic operations cannot protect accesses to complex data structures in the way that locks can, but they provide a very efficient way of serializing access to a single word.

What are atomic operations in C?

Atomic operations are intended to allow access to shared data without extra protection (mutex, rwlock, …). This may improve: ● single thread performance ● scalability ● overall system performance. Page 4.

How do atomic operations work?

An operation acting on shared memory is atomic if it completes in a single step relative to other threads. ... Any time two threads operate on a shared variable concurrently, and one of those operations performs a write, both threads must use atomic operations.