Commit 00061968 authored by Morten Rasmussen's avatar Morten Rasmussen Committed by Thomas Gleixner
Browse files

sched/fair: Remove wake_cap() 



Capacity-awareness in the wake-up path previously involved disabling
wake_affine in certain scenarios. We have just made select_idle_sibling()
capacity-aware, so this isn't needed anymore.

Remove wake_cap() entirely.

Signed-off-by: default avatarMorten Rasmussen <morten.rasmussen@arm.com>
[Changelog tweaks]
Signed-off-by: default avatarValentin Schneider <valentin.schneider@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
[Changelog tweaks]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200206191957.12325-5-valentin.schneider@arm.com
parent f8459197

kernel/sched/fair.c

+1 −29
Original line number Diff line number Diff line
@@ -6145,33 +6145,6 @@ static unsigned long cpu_util_without(int cpu, struct task_struct *p) 
	return min_t(unsigned long, util, capacity_orig_of(cpu));

}



/*

 * Disable WAKE_AFFINE in the case where task @p doesn't fit in the

 * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu.

 *

 * In that case WAKE_AFFINE doesn't make sense and we'll let

 * BALANCE_WAKE sort things out.

 */

static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)

{

	long min_cap, max_cap;



	if (!static_branch_unlikely(&sched_asym_cpucapacity))

		return 0;



	min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu));

	max_cap = cpu_rq(cpu)->rd->max_cpu_capacity;



	/* Minimum capacity is close to max, no need to abort wake_affine */

	if (max_cap - min_cap < max_cap >> 3)

		return 0;



	/* Bring task utilization in sync with prev_cpu */

	sync_entity_load_avg(&p->se);



	return !task_fits_capacity(p, min_cap);

}



/*

 * Predicts what cpu_util(@cpu) would return if @p was migrated (and enqueued)

 * to @dst_cpu.
@@ -6436,8 +6409,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f 
			new_cpu = prev_cpu;

		}



		want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu) &&

			      cpumask_test_cpu(cpu, p->cpus_ptr);

		want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr);

	}



	rcu_read_lock();