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    SubjectRe: reschedule_idle changes in ac kernels
    I ran the VolanoMark and TPC-H benchmarks on an 8 CPU system
    to observe the differences when changing the value at which
    preemptions are triggered. I used the 2.4.5 kernel as a basis
    and only changed the 'max_prio = ' statement in reschedule_idle()
    to change the preemption trigger threshold. In the 2.4.5 kernel
    the value of max_prio is set to 1.

    The results:

    In VolanoMark, changing the preemption trigger from 1 to 0
    resulted in a 4% drop in throughput.

    In TPC-H there was virtually no difference when going from
    1 to 0. If anything, the results were slightly better with
    0 as a threshold value as opposed to 1.

    My guess is that the threshold value was changed from 0 to
    1 in the 2.4 kernel for better performance with some workload.
    Anyone remember what that workload was/is?

    --
    Mike Kravetz mkravetz@sequent.com
    IBM Linux Technology Center
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