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    SubjectRe: [RFC/PATCH 0/3] sched: allow arch override of cpu power
    Ingo Molnar wrote:
    >
    > * Nathan Lynch <ntl@pobox.com> wrote:
    > > So it would be nice to have the scheduler slightly prefer primary
    > > threads on POWER6 machines. These patches, which allow the
    > > architecture to override the scheduler's CPU "power" calculation, are
    > > one possible approach, but I'm open to others. Please note: these
    > > seemed to have the desired effect on 2.6.25-rc kernels (2-3%
    > > improvement in a kernbench-like make -j <nr_cores>), but I'm not
    > > seeing this improvement with 2.6.26-rc kernels for some reason I am
    > > still trying to track down.
    >
    > ok, i guess that discrepancy has to be tracked down before we can think
    > about these patches - but the principle is OK.

    Great. I'll keep trying to figure out what's going on there.


    > One problem is that the whole cpu-power balancing code in sched.c is a
    > bit ... unclear and under-documented. So any change to this area should
    > begin at documenting the basics: what do the units mean exactly, how are
    > they used in balancing and what is the desired effect.
    >
    > I'd not be surprised if there were a few buglets in this area, SMT is
    > not at the forefront of testing at the moment. There's nothing
    > spectacularly broken in it (i have a HT machine myself), but the
    > concepts have bitrotten a bit. Patches - even if they just add comments
    > - are welcome :-)

    Okay, I'll have a look. Thanks Ingo.


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