On Tue, Mar 29, 2016 at 6:40 PM, Guus Sliepen <g...@tinc-vpn.org> wrote: > 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? > Personally I think tun could benefit greatly if it were implemented as a socket instead of character interface. One thing that could be much better is sending/receiving of meta data attached to skbuf. For instance GSO data could be in ancillary data in a socket instead of inline with packet data as tun seems to be doing now.
Tom > -- > Met vriendelijke groet / with kind regards, > Guus Sliepen <g...@tinc-vpn.org>
