Messages in this thread | | | Date | Tue, 24 Apr 2018 14:53:49 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/3] sched: limit cpu search and rotate search window for scalability |
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On Mon, Apr 23, 2018 at 05:41:16PM -0700, subhra mazumdar wrote: > Lower the lower limit of idle cpu search in select_idle_cpu() and also put > an upper limit. This helps in scalability of the search by restricting the > search window.
> @@ -6297,15 +6297,24 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t > > if (sched_feat(SIS_PROP)) { > u64 span_avg = sd->span_weight * avg_idle; > - if (span_avg > 4*avg_cost) > + if (span_avg > 2*avg_cost) { > nr = div_u64(span_avg, avg_cost); > - else > - nr = 4; > + if (nr > 4) > + nr = 4; > + } else { > + nr = 2; > + } > }
Why do you need to put a max on? Why isn't the proportional thing working as is? (is the average no good because of big variance or what)
Again, why do you need to lower the min; what's wrong with 4?
The reason I picked 4 is that many laptops have 4 CPUs and desktops really want to avoid queueing if at all possible.
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