linux patch for high-speed networking (incl htcp)

From: Douglas Leith
Date: Tue Mar 30 2004 - 03:52:00 EST


Hi,

I've put a linux patch at www.hamilton.ie/net that might be of interest to
those working on tcp for high-speed networks.

One of the issues that has become pretty clear from initial tests of new tcp
congestion control algorithms in high-speed regimes is that the standard
linux tcp stack often performs poorly due to implementation problems. This
was one of the main themes at the recent PFLDnet workshop at Argonne. Sack
processing is very inefficient, leading to frequent timeouts, the burst
moderation implementation often does more harm than good and packet
reordering etc (which seems to be quite common on real networks) degrades
throughput. I've tried to document some of these problems in the report at
http://www.hamilton.ie/net/LinuxHighSpeed.pdf. The problems are
sufficiently serious that they frequently obstruct comparisons and
evaluation of proposed tcp congestion control algorithms. The patch at
http://www.hamilton.ie/net/2.4.23.HSv4.patch.gz tries to address these
problems, and seems to work fairly well in the tests I've carried out on a
variety of machines and network paths. Its still very much experimental
code, however, and comments would be appreciated. The code is a patch
against linux 2.4.23 and includes web100 (with implementations of scalable
cp and high-speed tcp) and also an implementation of htcp.

Doug

Hamilton Institute
www.hamilton.ie

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