Well even doing it on a file is bad. It's per file, but also, it's (necessarily) the in-core state of that file, as a Linux man page says. So if you do a writ

Well even doing it on a file is bad. It's per file, but also, it's (necessarily) the in-core state of that file, as a Linux man page says. So if you do a write on one thread, wait for that write to complete, and then signal another thread to do an fsync, I don't really know what happens.