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Re: TCP performance drop 2.6.6->2.6.7

To: Baruch Even <baruch@xxxxxxxxx>
Subject: Re: TCP performance drop 2.6.6->2.6.7
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Wed, 13 Apr 2005 11:20:36 -0700
Cc: netdev@xxxxxxxxxxx, "David S. Miller" <davem@xxxxxxxxxxxxx>
In-reply-to: <425C60DD.5090007@xxxxxxxxx>
Organization: Open Source Development Lab
References: <425C493B.5040206@xxxxxxxxx> <20050412160752.46c82f0c@xxxxxxxxxxxxxxxxx> <425C60DD.5090007@xxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
On Wed, 13 Apr 2005 00:59:25 +0100
Baruch Even <baruch@xxxxxxxxx> wrote:

> Stephen Hemminger wrote:
> > On Tue, 12 Apr 2005 23:18:35 +0100
> > Baruch Even <baruch@xxxxxxxxx> wrote:
> >>The setup for the tests, vanilla kernels, dummynet with 100 Mbit/s and 
> >>40ms rtt using the BIC protocol. No patches applied whatsoever.

What is the queue length? Better yet what is the exact commandline
used to setup dummynet.

> >>
> >>iperf tests for 2.6.6 get about 90Mbit/s while 2.6.7 gets 30Mbit/s.
> > 
> > 
> > Haven't measured old kernels recently. But haven't seen that with the
> > newest stuff I tested last night. At 40ms delay  with netem
> > over 1G to 100M bridge.
> >     Reno    99.6
> >     Vegas   61.6
> >     BIC       97.8
> >     Hstcp    99.4
> >     Westwood 99.4
> 
> I've now tested 2.6.11.7 and I get about 50Mbit/s, it starts at about 
> 100 and drops to about 45. Tested for about a minute but it didn't show 
> signs of recovery.
> 
> > What are your sysctl settings. 
> 
> Attached.
> 
> Baruch

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