Re: [PATCH] sched, fair: Allow a small degree of load imbalance between SD_NUMA domains

Rik van Riel
2019-12-19T02:58:24Z

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On Wed, 2019-12-18 at 15:44 +0000, Mel Gorman wrote:

> + /*
> + * Ignore imbalance unless busiest sd is close
> to 50%
> + * utilisation. At that point balancing for
> memory
> + * bandwidth and potentially avoiding
> unnecessary use
> + * of HT siblings is as relevant as memory
> locality.
> + */
> + imbalance_max = (busiest->group_weight >> 1) -
> imbalance_adj;
> + if (env->imbalance <= imbalance_adj &&
> + busiest->sum_nr_running < imbalance_max) {
> + env->imbalance = 0;
> + }
> + }
> return;
> }

I can see how the 50% point is often great for HT,
but I wonder if that is also the case for SMT4 and
SMT8 systems...

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