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Re: bad TSO performance in 2.6.9-rc2-BK

To: John Heffner <jheffner@xxxxxxx>
Subject: Re: bad TSO performance in 2.6.9-rc2-BK
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Thu, 30 Sep 2004 13:23:21 -0700
Cc: ak@xxxxxxx, niv@xxxxxxxxxx, herbert@xxxxxxxxxxxxxxxxxxx, andy.grover@xxxxxxxxx, anton@xxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <Pine.NEB.4.33.0409301320510.13549-100000@dexter.psc.edu>
References: <Pine.NEB.4.33.0409292008110.3434-100000@dexter.psc.edu> <Pine.NEB.4.33.0409301320510.13549-100000@dexter.psc.edu>
Sender: netdev-bounce@xxxxxxxxxxx
On Thu, 30 Sep 2004 13:25:46 -0400 (EDT)
John Heffner <jheffner@xxxxxxx> wrote:

> On Wed, 29 Sep 2004, John Heffner wrote:
> 
> > On Wed, 29 Sep 2004, John Heffner wrote:
> >
> > > Using iperf, I'm getting ~ the same speed to a slow p3 receiver (680
> > > Mbits) with TSO on or off right now.  Haven't tried netperf.
> >
> > Netperf does not work well for me (350 Mbits).  Something to investigate.
> 
> I tried again, and it does not even work this well.  The connection hangs
> at the end in state FIN_WAIT1 with 101361 bytes in the Send-Q.  It seems
> that the whole interface dies.  (Maybe it's sending something invalid to
> the TSO engine?)  When I bring the interface down then back up again, the
> connection terminates normally.
> 
> Don't have this problem with iperf, strange.

Even stranger is that with current netperf tg3-->tg3 works perfectly fine
for me with TSO enabled.  I'm getting clean 700Mbit transfers through
my D-Link DGS-1008T switch as long as netperf doesn't do something silly
like use tiny send/receiver buffers.

I've never had a transfer stall either.

Please help debug this John since I'm not seeing this here.

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