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Date: Thu, 16 Nov 2006 15:17:26 +0000
From: Dieter <freebsd@sopwith.solgatos.com>
Subject: TCP parameters
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In the process of debugging a not-working-so-well TCP
application, I've been asked to provide:

> cat /proc/sys/net/ipv4/tcp_window_scaling
> cat /proc/sys/net/ipv4/tcp_wmem

Which of course results in "No such file or directory".

I suspect these are from Linux.  Are there equivalent
parameters in FreeBSD 6.x ?

The other end (non-FreeBSD non-open-source) is sending
real-time data, and apparently is not able to keep up,
its memory fills up, and it starts dropping packets.  I
suspect the problem is a combination of too much latency
(FreeBSD not sending ACKs fast enough) and not enough window
size.

net.inet.tcp.recvspace and .sendspace  seem relevant,
anything else?  I'm not a TCP wizard, so please feel free
to point out things that should be obvious.  :-)

I doubt that the BSD network stack has anything to do with this,
but perhaps there is something that could be tweaked to help out.
I'm hoping that updating the Ethernet device drivers (bge, nve)
will result in less latency.

Then there is userland:

Anyone want to code review a very simple 80 line TCP-to-stdout utility?

I looked at socat, but it isn't LP64 clean.