We (Varnish Software) still use mmap, just not for writing. The problem with mmap is that you can't use it to wrote whole pages at a time as the CPU will trap a

We (Varnish Software) still use mmap, just not for writing. The problem with mmap is that you can't use it to wrote whole pages at a time as the CPU will trap and ask the OS to merge the page you're writing to. mmaps are still great as the page cache still manages the split cache between disk and memory.