RE: Increasing TCP Window Size in FreeBSD.

You may have to tune few more - kern.ipc.maxsockbuf, kern.ipc.nmbclusters.

http://www.cs.unc.edu/~jeffay/dirt/FAQ/sobuf.html
http://people.freebsd.org/~adrian/sysctl.descriptions

Regards,
Gireesh


-----Original Message-----
From: owner-freebsd-current_at_freebsd.org
[mailto:owner-freebsd-current_at_freebsd.org] On Behalf Of David Somayajulu
Sent: 10 February 2011 10:24
To: freebsd-current_at_freebsd.org
Subject: Increasing TCP Window Size in FreeBSD.

I have been using iperf in server mode to do some performance analysis.
I was trying to increase the Receive TCP Window Size via

sysctl net.inet.tcp.recvspace=<value>

I noticed that I could increase it atmost to 128Kbytes (131072). Any value
above 128k, results in a failure to get the requested window size, resulting
in a failure of "iperf -s -w <windowsize>".

How can I increase it beyond 128Kbytes ?

Here are some relevant sysctl values I have been using:

net.inet.tcp.rfc1323: 1
net.inet.tcp.recvspace: 131072
net.inet.tcp.recvbuf_max: 4096000
net.inet.tcp.recvbuf_inc: 65536
net.inet.tcp.recvbuf_auto: 1

Thanks
david S.

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