https://man7.org/linux/man-pages/man2/membarrier.2.html https://man7.org/linux/man-pages/man2/membarrier.2.html provides a good example of when a processor memo

https://man7.org/linux/man-pages/man2/membarrier.2.html https://man7.org/linux/man-pages/man2/membarrier.2.html provides a good example of when a processor memory barrier is eliminated but a compiler memory barrier is still required.