Date: Tue, 14 Sep 2010 17:41:03 +0200 From: Andre Oppermann <oppermann@networx.ch> To: Fabien Thomas <fabien.thomas@netasq.com> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org Subject: Re: TCP loopback socket fusing Message-ID: <4C8F978F.1030707@networx.ch> In-Reply-To: <A9862681-6A4D-43A3-9A26-C71A54CF86F0@netasq.com> References: <4C8E0C1E.2020707@networx.ch> <A9862681-6A4D-43A3-9A26-C71A54CF86F0@netasq.com>
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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. -- 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" > > >
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