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