Re: [PATCH] sched, fair: Allow a small load imbalance between low utilisation SD_NUMA domains v3

[Mel Gorman]

On Mon, Jan 06, 2020 at 10:47:18AM -0500, Rik van Riel wrote:
> > +			imbalance_adj = (100 / (env->sd->imbalance_pct
> > - 100)) - 1;
> > +
> > +			/*
> > +			 * Allow small imbalances when the busiest
> > group has
> > +			 * low utilisation.
> > +			 */
> > +			imbalance_max = imbalance_adj << 1;
> > +			if (busiest->sum_nr_running < imbalance_max)
> > +				env->imbalance -= min(env->imbalance,
> > imbalance_adj);
> > +		}
> > +
> 
> Wait, so imbalance_max is a function only of
> env->sd->imbalance_pct, and it gets compared
> against busiest->sum_nr_running, which is related
> to the number of CPUs in the node?
> 

It's not directly related to the number of CPUs in the node. Are you
thinking of busiest->group_weight?

-- 
Mel Gorman
SUSE Labs