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SubjectRe: Network performance degradation from 2.6.11.12 to 2.6.16.20

>> Harry Edmon <harry@atmos.washington.edu> wrote:
>>
>>> I have a system with a strange network performance degradation from
>>> 2.6.11.12 to most recent kernels including 2.6.16.20 and 2.6.17-rc6.
>>> The system is has Dual single core Xeons with hyperthreading on.
<cut>

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).


Cheers,
Jesper Brouer

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