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Subject: Re: Huge performance degradation for UDP between 2.4.17 and 2.6
From: Eric Dumazet <eric.dumazet@gmail.com>
To: leroy christophe <christophe.leroy@c-s.fr>
Cc: linux-kernel@vger.kernel.org
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Date: Thu, 02 Aug 2012 16:13:56 +0200
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On Thu, 2012-08-02 at 14:27 +0200, leroy christophe wrote:
> Hi
> 
> I'm having a big issue with UDP. Using a powerpc board (MPC860).
> 
> With our board running kernel 2.4.17, I'm able to send 160000 voice 
> packets (UDP, 96 bytes per packet) in 11 seconds.
> With the same board running either Kernel 2.6.35.14 or Kernel 3.4.7, I 
> need 55 seconds to send the same amount of packets.
> 
> 
> Is there anything to tune in order to get same output rate as with 
> Kernel 2.4 ?

kernel size is probably too big for your old / slow cpu.

Maybe you added too many features on your 3.4.7 kernel. (netfilter ?
SLUB debugging ...)

Its hard to say, 2.4.17 had less features and was faster.