Date: Sun, 28 Dec 2008 23:18:32 +1100 From: Lawrence Stewart <lastewart@swin.edu.au> To: freebsd-net@freebsd.org Subject: CFT: TCP Appropriate Byte Counting (RFC3465) Patch Message-ID: <49576E98.2070403@swin.edu.au>
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Hi all, The first chunk of work from the FreeBSD Foundation sponsored "Improving the FreeBSD TCP Implementation" project [1] is ready for some public review and testing. Being my first project related email, I'll point out to anyone interested that you can track the overall project via [2,3]. TCP appropriate byte counting (ABC) [4] addresses a congestion control related issue introduced by the early TCP specifications. It suggests increasing the congestion window by the number of bytes acknowledged by a TCP ACK, as opposed to the current scheme which relies on an approximation driven by ACK clocking. ABC will most commonly benefit FreeBSD by improving TCP sender performance when communicating with a delayed acknowledgement enabled receiver. The patch against 8-CURRENT svn rev 186471 can be found at [5] along with a readme [6] covering all the necessary juicy bits in more detail. I welcome all feedback and reports of both success or failure. I'm currently working on analysing the small-scale dynamic behaviour effects of the patch in detail, so I'm not asking you to go into minute detail with your testing. I'd like to hear that running with an ABC enabled kernel allows TCP to work as it did previously and is not negatively impacting throughput for any particular TCP workloads you have available for testing. I aim to commit this within the next week or so assuming nothing bad turns up in this round of testing. Cheers, Lawrence http://caia.swin.edu.au/ [1] http://www.freebsdfoundation.org/project%20announcements.shtml#Lawrence [2] http://svn.freebsd.org/viewvc/base/projects/tcp_ffcaia2008_8.x/ [3] http://lists.freebsd.org/mailman/listinfo/svn-src-projects [4] http://www.rfc-editor.org/rfc/rfc3465.txt [5] http://people.freebsd.org/~lstewart/patches/tcp_ffcaia2008/tcp_abc_8.x.r186471.patch [6] http://people.freebsd.org/~lstewart/patches/tcp_ffcaia2008/tcp_abc_8.x.r186471.patch.readme
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