Question about the "connected" UDP sockets

[Sepherosa Ziehau]

On Fri, Dec 27, 2013 at 1:49 AM, Oleg Moskalenko <mom040267 at gmail.com> wrote:
> Hi
>
> I cannot find the information about the implementation details of the
> "connected" UDP sockets in FreeBSD. I know that in older Linux kernels all


You could start from sys/netinet/udp_usrreq.c:udp_connect().


> UDP sockets are stored in a hash table - and the remote IP:port are not
> used for the hash calculation, so the performance is awful when you have
> thousands "connected" UDP sockets on the same local IP:port address. So a
> UDP packet incoming to the local address has to go through the long list of
> sockets to find the proper destination.
>
> How it is done in the FreeBSD ? Are the UDP "connected" sockets using a
> hash table with key based upon 5-tuple (protocol, remote-ip, remote-port,
> local-ip, local-port} ?


UDP uses its own hash table for "connected" sockets (inpcb actually).
The "connected" inpcbs are hashed using lport/fport/laddr/faddr
(4-tuple).

Best Regards,
sephe