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Re: bad TSO performance in 2.6.9-rc2-BK

To: "David S. Miller" <davem@xxxxxxxxxxxxx>
Subject: Re: bad TSO performance in 2.6.9-rc2-BK
From: Andi Kleen <ak@xxxxxxx>
Date: Wed, 29 Sep 2004 01:55:34 +0200
Cc: herbert@xxxxxxxxxxxxxxxxxxx, niv@xxxxxxxxxx, andy.grover@xxxxxxxxx, anton@xxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20040928163509.624a748b.davem@xxxxxxxxxxxxx>
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On Tue, 28 Sep 2004 16:35:09 -0700
"David S. Miller" <davem@xxxxxxxxxxxxx> wrote:

> On Wed, 29 Sep 2004 01:27:57 +0200
> Andi Kleen <ak@xxxxxxx> wrote:
> 
> > I tried to re-test it but I didn't get very far because the kernel
> > with your patch crashes regularly during netperf. No serial console,
> > but the backtrace is {tcp_ack+877} {tcp_rcv_established+350} ... 
> > Before that there are a few "retrans out leaked" messages.
> 
> You might be missing the topmost part of the backtrace which is probably
> in tcp_clean_rtx_queue() or even more likely tcp_tso_acked() where there
> are several assertions present.
> 
> I guess your compiler is auto-inlining those functions for you,
> can you reproduce the crash with perhaps the noinline attribute
> added to those two functions I mention above so we can get a
> precise backtrace?

Hmpf, it stopped crashing after I recompiled without -funit-at-a-time
Maybe it is some compiler issue.

-Andi

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