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    SubjectRe: [announce] CFS-devel, performance improvements
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    On Thu, 2007-09-13 at 19:06 +0200, Peter Zijlstra wrote:
    > On Thu, 2007-09-13 at 18:50 +0200, Roman Zippel wrote:
    >
    > > I never claimed to understand every detail of CFS, I can _guess_ what
    > > _might_ have been intended, but from that it's impossible to know for
    > > certain how important they are. Let's take this patch fragment:
    > >
    >
    > delta_fair = se->delta_fair_sleep;
    >
    > we slept that much
    >
    > > - /*
    > > - * Fix up delta_fair with the effect of us running
    > > - * during the whole sleep period:
    > > - */
    > > - if (sched_feat(SLEEPER_AVG))
    > > - delta_fair = div64_likely32((u64)delta_fair * load,
    > > - load + se->load.weight);
    >
    > if we would have ran we would not have been removed from the rq and the
    > weight would have been: rq_weight + weight
    >
    > so compensate for us having been removed from the rq by scaling the
    > delta with: rq_weight/(rq_weight + weight)
    >
    > > - delta_fair = calc_weighted(delta_fair, se);
    >
    > scale for nice levels
    >

    Or at least, I think that is how to read it :-)

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