2.6.12 Performance problems

Danial Thom
2005-08-21T15:47:04Z

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.

Danial

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