Re: 2.6.12 Performance problems

[Patrick McHardy <kaber@trash.net>]

Danial Thom wrote:
> I just started fiddling with 2.6.12, and there
> seems to be a big drop-off in performance from
> 2.4.x in terms of networking on a uniprocessor
> system. Just bridging packets through the
> machine, 2.6.12 starts dropping packets at
> ~100Kpps, whereas 2.4.x doesn't start dropping
> until over 350Kpps on the same hardware (2.0Ghz
> Opteron with e1000 driver). This is pitiful
> prformance for this hardware. I've 
> increased the rx ring in the e1000 driver to 512
> with little change (interrupt moderation is set
> to 8000 Ints/second). Has "tuning" for MP 
> destroyed UP performance altogether, or is there
> some tuning parameter that could make a 4-fold
> difference? All debugging is off and there are 
> no messages on the console or in the error logs.
> The kernel is the standard kernel.org dowload
> config with SMP turned off and the intel ethernet
> card drivers as modules without any other
> changes, which is exactly the config for my 2.4
> kernels.

Do you have netfilter enabled? Briging netfilter was
added in 2.6, enabling it will influence performance
negatively. Otherwise, is this performance drop
visible in other setups besides bridging as well?