> By making frequent use of msync(addr, length, MS_INVALIDATE), data written in this manner can be shared between processes that both map the same file. mmap(2

> By making frequent use of msync(addr, length, MS_INVALIDATE), data written in this manner can be shared between processes that both map the same file. mmap(2), msync(2). MMAP_SHARED means that the same physical memory pages are available via different virtual addresses. All the writes are visible immediately, at least in the same way as in the regular memory (you may still need mfence-es or a cache flush depending on CPU). MS_INVALIDATE is essentially a no-op on Linux.