Messages in this thread |  | | | Subject | Re: [announce] CFS-devel, performance improvements | | From | Peter Zijlstra <> | | Date | Thu, 13 Sep 2007 19:06:05 +0200 |
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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
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