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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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