Sendfile isn't async, it just avoids the user space copy, and in some cases the copy from the fd to the socket. Aio doesn't require xfs, just O_DIRECT, which c

Sendfile isn't async, it just avoids the user space copy, and in some cases the copy from the fd to the socket. Aio doesn't require xfs, just O_DIRECT, which can be tricky to get right and more work than userspace guys want to deal with.