Linux 内核内存屏障

Question

我是 Linux 内核编程的新手。我很困惑 the memory barriers文档，在保证一章中。

Overlapping loads and stores within a particular CPU will appear to be ordered within that CPU.

*X = c; d = *X;

the CPU will only issue:

STORE *X = c, d = LOAD *X

然后是另一个例子:

It must be assumed that overlapping memory accesses may be merged or discarded.

*A = X; Y = *A;

we may get either of:

STORE *A = X; Y = LOAD *A;
STORE *A = Y = X;

他们看起来很像，这两个例子有什么区别？

Answer 1

你是对的，文档不正确。实际上您的文件版本不是最新的。 3.8-rc3 中有一个提交解决了这个问题: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=f191eec58803e1e16c3421638cdcc9195c425851

希望对您有所帮助。马蒂亚斯