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SubjectRe: Network performance degradation from to

>> Harry Edmon <> wrote:
>>> I have a system with a strange network performance degradation from
>>> to most recent kernels including and 2.6.17-rc6.
>>> The system is has Dual single core Xeons with hyperthreading on.

Hi Harry

Can you check which "high-res timesource" you are using?

In the kernel log look for:
kernel: Using tsc for high-res timesource
kernel: Using pmtmr for high-res timesource

I have experinced some network performance degradation when using the
"pmtmr" timesource, on a Opteron AMD system. It seems that the default
timesource change between 2.6.15 to 2.6.16.

If you use "pmtmr" try to reboot with kernel option "clock=tsc".

On my Opteron AMD system i normally can route 400 kpps, but with
timesource "pmtmr" i could only route around 83 kpps. (I found the timer
to be the issue by using oprofile).

Jesper Brouer

MSc. Master of Computer Science
Dept. of Computer Science, University of Copenhagen
Author of
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