To: linux-kernel@vger.kernel.org
From: Stephen Hemminger <shemminger@osdl.org>
Subject: Re: Network slowdown from 2.6.7 to 2.6.9
Date: Tue, 23 Nov 2004 10:04:50 -0800
Organization: Open Source Development Lab
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On Mon, 22 Nov 2004 15:38:16 -0800
Harry Edmon <harry@atmos.washington.edu> wrote:

> Tried them all - none of them helped.  Use "ntop" I can see that my 
> throughput on the Intel gigabit ethernet interface on the system maxes 
> out at 15.2 Mbps with 2.6.9.  With 2.6.7 it made it to 35 Mbps.
> 
> Does anyone have any other suggestions as to what to look for to 
> diagnose this problem?

Well, before the TSO changes, if TSO was enabled then TCP would not obey slow
start or do congestion control properly.  Did you increase the TCP send/receive
buffers (sysctl's net.ipv4.tcp_rmem and net.ipv4.tcp_wmem)? You may just
be window limited.  Also, 2.6.9 has TCP bugs with TSO that can cause panic's.
These have been fixed in 2.6.10-rc2.

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