Re: [PATCH v3 04/10] sched/fair: rework load_balance

[Peter Zijlstra]

On Tue, Oct 08, 2019 at 05:30:02PM +0200, Vincent Guittot wrote:

> This is how I plan to get ride of the problem:
> +		if (busiest->group_weight == 1 || sds->prefer_sibling) {
> +			unsigned int nr_diff = busiest->sum_h_nr_running;
> +			/*
> +			 * When prefer sibling, evenly spread running tasks on
> +			 * groups.
> +			 */
> +			env->migration_type = migrate_task;
> +			lsub_positive(&nr_diff, local->sum_h_nr_running);
> +			env->imbalance = nr_diff >> 1;
> +			return;
> +		}

I'm thinking the max_t(long, 0, ...); variant reads a lot simpler and
really _should_ work given that -fno-strict-overflow / -fwrapv mandates
2s complement.