Date: Tue, 14 Sep 2010 11:18:14 +0200 From: Fabien Thomas <fabien.thomas@netasq.com> To: Andre Oppermann <oppermann@networx.ch> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org Subject: Re: TCP loopback socket fusing Message-ID: <A9862681-6A4D-43A3-9A26-C71A54CF86F0@netasq.com> In-Reply-To: <4C8E0C1E.2020707@networx.ch> References: <4C8E0C1E.2020707@networx.ch>
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Great, This will maybe kill the long time debate about "my loopback is slow vs = linux" To have the best of both world what about a socket option to = enable/disable fusing: can be useful when you need to see some connection "packetized". Fabien On 13 sept. 2010, at 13:33, Andre Oppermann wrote: > When a TCP connection via loopback back to localhost is made the whole > send, segmentation and receive path (with larger packets though) is = still > executed. This has some considerable overhead. >=20 > To short-circuit the send and receive sockets on localhost TCP = connections > I've made a proof-of-concept patch that directly places the data in = the > other side's socket buffer without doing any packetization and other = protocol > overhead (like UNIX domain sockets). The connections setup (SYN, = SYN-ACK, > ACK) and shutdown are still handled by normal TCP segments via = loopback so > that firewalling stills works. The actual payload data during the = session > won't be seen and the sequence numbers don't move other than for SYN = and FIN. > The sequence are remain valid though. Obviously tcpdump won't see any = data > transfers either if the connection has fused sockets. >=20 > Preliminary testing (with WITNESS and INVARIANTS enabled) has shown = stable > operation and a rough doubling of the throughput on loopback = connections. > I've tested most socket teardown cases and it behaves fine. I'm not = entirely > sure I've got all possible path's but the way it is integrated should = properly > defuse the sockets in all situations. >=20 > Testers and feedback wanted: >=20 > http://people.freebsd.org/~andre/tcp_loopfuse-20100913.diff >=20 > --=20 > Andre >=20 > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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