Linux TCP patches available for 2.2.17-14 kernel

[Josip Loncaric]

Red Hat just released their Linux kernel to 2.2.17-14 so I updated my
TCP patches to use this kernel.  See:

  http://www.icase.edu/~josip/LinuxTCP-patches.html

This web page also references sfperf, a script which uses netperf to
investigate the performance of various tcp_delack_strategy (s) and
tcp_faster_timeout (f) settings.  This script takes about an hour to
run, and typically recommends (s:3,f:1) as good values.  IMPORTANT: your
target host must allow at least 600 netserver connections per minute
(see the web page for more info).

Sfperf collects timings of unidirectional streaming of 100,000 single
byte TCP messages, then picks consistently fast settings.  The
recommended s and f settings on our PIII/800 nodes running Linux
2.2.17-14 (with patches) are:

s:  3 f: 1  time:    0.28 +/-   0.10 best:   0.19 worst:   0.75 seconds
s:  3 f: 0  time:    0.30 +/-   0.11 best:   0.19 worst:   0.73 seconds
s:  2 f: 1  time:    0.40 +/-   0.30 best:   0.22 worst:   2.47 seconds
s:  2 f: 0  time:    0.45 +/-   0.35 best:   0.21 worst:   2.92 seconds
s:  4 f: 0  time:    0.62 +/-   0.57 best:   0.19 worst:   2.94 seconds
s:  4 f: 1  time:    0.69 +/-   0.69 best:   0.19 worst:   3.93 seconds

With the TCP patches turned off (s:10,f:0) the same test takes 2.8 times
longer on the average because the unpatched kernel's performance is less
consistent (the worst cases are much worse): 

s: 10 f: 0  time:    0.79 +/-   0.80 best:   0.19 worst:   3.01 seconds

Sincerely,
Josip

P.S.  Red Hat Linux kernel 2.2.17-14 has a minor bug in IP masquerade
code (not related to the TCP patches).  See
http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=21604 if you get
compilation errors in ip_masq.c.


-- 
Dr. Josip Loncaric, Senior Staff Scientist        mailto:josip at icase.edu
ICASE, Mail Stop 132C           PGP key at http://www.icase.edu./~josip/
NASA Langley Research Center             mailto:j.loncaric at larc.nasa.gov
Hampton, VA 23681-2199, USA    Tel. +1 757 864-2192  Fax +1 757 864-6134