On Sat, Mar 04, 2000 at 08:21:20PM +0000, Paul Robinson wrote:
> I've been trying to get TCP/IP performance as fast as possible by playing
> around with sysctl (playing in the net.inet area) and so on, and was
> wondering if there were any comprehensive resources on this that I've
> missed.
I haven't heard of any algorithms to tune TCP automagically. When I
work with people who have satellite hops in their network, we usually
have to tune the TCP knobs by hand, trying a large number of transactions
and statistically minimising transaction time.
> Whenever I do a sysctl -d -a to get a list of descriptions, I get
> the following on 3.2-RELEASE:
>
> sysctl: sysctl name -1 1024 2: No such file or directory
I get that too, but I had never noticed because I didn't know about
the "d" flag :) FreeBSD 3.3-RELEASE FreeBSD 3.3-RELEASE #1:
Sat Dec 4 15:21:53 NZDT 1999.
> Any idea as to what's going on here?
>
> Also, I seem to remember hearing about a method used on SunOS to send the
> first four bytes of the data payload back with the SYN ACK which gives the
> appearance of improved performance on benchmarks. Does anybody know as to
> whether this is possible under any version of FreeBSD? I'll move to 4.0 if
> I have to. :)
This is what I generally do before I try to tune anything further:
# turn on RFC1323 extensions (timestamps, PAWS, window scaling, etc) These
# seem to be on by default in 3.3, YMMV for 3.2.
sysctl -w net.inet.tcp.rfc1323=1
# open up the send and receive windows to 131072 bytes; the default
# 16k is too small for people living oceans away from the majority of
# their content
sysctl -w net.inet.tcp.sendspace=131072
sysctl -w net.inet.tcp.recvspace=131072
# If 4.0 (or later 3.x's) support SACK, turn that on here too. SACK is
# cool :) This is what I use on OpenBSD:
sysctl -w net.inet.tcp.sack=1
# If you want to try transactional TCP (T/TCP, RFC1644) which is the
# thing you mentioned with the single segment with SIN, ACK, FIN + payload,
# turn this on:
sysctl -w net.inet.tcp.rfc1644=1
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