Date: Thu, 12 Sep 1996 15:05:04 -0400 From: Garrett Wollman <wollman@lcs.mit.edu> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: hackers@freebsd.org, wollman@lcs.mit.edu, phk@freebsd.org Subject: Changing default TCP window size ? Message-ID: <9609121905.AA29311@halloran-eldar.lcs.mit.edu> In-Reply-To: <199609112117.XAA08985@labinfo.iet.unipi.it> References: <199609112117.XAA08985@labinfo.iet.unipi.it>
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<<On Wed, 11 Sep 1996 23:17:07 +0200 (MET DST), Luigi Rizzo <luigi@labinfo.iet.unipi.it> said:
> How do I force TCP (or the OS) to use a window size different from the
> default 16K ?
> The following code
> mywin=DESIRED_WINDOW_SIZE;
> setsockopt(f, SOL_SOCKET, SO_SNDBUF, (char *)&mywin, sizeof mywin)
> appears to set the value correctly (it can be read back with
> getsockopt) but then it appears not to have any effect on TCP
> (monitoring the connection with netstat -na always shows a Send-Q
> around 16KB, and the throughput in window-limited configurations
> remains unchanged).
This is a conflict that needs to be resolved between the
option-processing code and the code that attempts to set the socket
buffer size based on what's in the route. I can't give you a
fully-fleshed-out solution, but essentially the code needs to check if
there is a buffer size specified via setsockopt, and if there is, then
it should ignore the values in the route (or perhaps it should use the
lock bits in the route to indicate some sort of clamping). I have a
long-standing bug report form Matthew Dillon about this, but it has
not had a sufficiently high priority to get done. Come up with a
good fix and I'll take it.
-GAWollman
--
Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the same
wollman@lcs.mit.edu | O Siem / The fires of freedom
Opinions not those of| Dance in the burning flame
MIT, LCS, ANA, or NSA| - Susan Aglukark and Chad Irschick
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