I'm trying to reduce system call overhead when reading/writing to/from a
tun device in userspace. For sockets, one can use sendmmsg()/recvmmsg(),
but a tun fd is not a socket fd, so this doesn't work. I'm see several
options to allow userspace to read/write multiple packets with one
syscall:
- Implement a TX/RX ring buffer that is mmap()ed, like with AF_PACKET
sockets.
- Implement a ioctl() to emulate sendmmsg()/recvmmsg().
- Add a flag that can be set using TUNSETIFF that makes regular
read()/write() calls handle multiple packets in one go.
- Expose a socket fd to userspace, so regular sendmmsg()/recvmmsg() can
be used. There is tun_get_socket() which is used internally in the
kernel, but this is not exposed to userspace, and doesn't look trivial
to do either.
What would be the right way to do this?
--
Met vriendelijke groet / with kind regards,
Guus Sliepen <[email protected]>
