memory 线程之间的栅栏/障碍如何与其他线程中的栅栏/障碍交互？

Question

What is the interaction of memory fences in different threads?

More particularly does a memory fence in a thread only prevents the reordering of instructions within the thread or there is there synchronising among the threads like one thread waits until the corresponding fence is reached in another thread? What happens is multiple threads have the same type of fence and multiple threads have paired fences? What type of fences needs to pair together among threads and how are they used? What are the effects if the code with memory fences is run in a single-threaded fashion?

Answer 1

A memory barrier is nothing like the barrier tag.

Memory barriers only order the local core's own accesses to coherent shared memory, because that's all that's needed to be able to recover sequential consistency. There is no direct interaction with other threads / cores.

If you want synchronization between threads, use release/acquire ordering.https://preshing.com/20120913/acquire-and-release-semantics/