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Re: bad TSO performance in 2.6.9-rc2-BK

To: Andi Kleen <ak@xxxxxxx>
Subject: Re: bad TSO performance in 2.6.9-rc2-BK
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Mon, 27 Sep 2004 16:37:51 -0700
Cc: jheffner@xxxxxxx, ak@xxxxxxx, niv@xxxxxxxxxx, andy.grover@xxxxxxxxx, anton@xxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20040927232554.GB15825@xxxxxxxxxxxxx>
References: <20040923161141.4ea9be4c.davem@xxxxxxxxxxxxx> <Pine.NEB.4.33.0409271416360.14606-100000@xxxxxxxxxxxxxx> <20040927160411.22b44f48.davem@xxxxxxxxxxxxx> <20040927232554.GB15825@xxxxxxxxxxxxx>
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On Tue, 28 Sep 2004 01:25:55 +0200
Andi Kleen <ak@xxxxxxx> wrote:

> Unfortunately not - with the patch applied I still get 27MB/s

And without TSO you get?  How exactly are you running netperf
and are you going through a switch?  I want to reproduce your
test case exactly here although using tg3 instead of e1000 :)

> Looking at the tcpdump the ack clock goes completely out of sync,
> the ratio is 4 packets per ack. The sender seems to send packets
> faster than the target can ack them. It eventually stops for a 
> short time until it gets the ack

Hmmm, thanks for the trace.

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