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Date: Tue, 31 Dec 2013 11:38:56 +0800
Message-ID: <CAMOc5cyhSB1Y24ajEJuKTdWE60-A4aVZrF3pSa0enB2DJCWNuw@mail.gmail.com>
Subject: Re: Question about the "connected" UDP sockets
From: Sepherosa Ziehau <sepherosa@gmail.com>
To: Oleg Moskalenko <mom040267@gmail.com>
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Cc: FreeBSD Net <freebsd-net@freebsd.org>
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On Fri, Dec 27, 2013 at 1:49 AM, Oleg Moskalenko <mom040267@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