Date: Tue, 14 Sep 2010 18:08:34 +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: <89E74A8F-4FF9-482B-83D0-3D076F0E41E4@netasq.com> In-Reply-To: <4C8F978F.1030707@networx.ch> References: <4C8E0C1E.2020707@networx.ch> <A9862681-6A4D-43A3-9A26-C71A54CF86F0@netasq.com> <4C8F978F.1030707@networx.ch>
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On 14 sept. 2010, at 17:41, Andre Oppermann wrote: > On 14.09.2010 11:18, Fabien Thomas wrote: >> 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". > > A sysctl to that effect is already in the patch. yes, i'm just wondering on a per connection setting. > > -- > Andre > >> 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. >>> >>> 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. >>> >>> 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. >>> >>> Testers and feedback wanted: >>> >>> http://people.freebsd.org/~andre/tcp_loopfuse-20100913.diff >>> >>> -- >>> Andre >>> >>> _______________________________________________ >>> 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" >> >> >> >help
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