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Commit 28e8cb96 authored by Patrick Bellasi's avatar Patrick Bellasi Committed by John Stultz
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FIX: sched/tune: update usage of boosted task utilisation on CPU selection 



A boosted task needs to be scheduled on a CPU which can grant a minimum
capacity which is higher than its utilization.
However, a task can be allocated on a CPU which already provides an utilization
which is higher than the task boosted utilization itself.
Moreover, with the previous approach a task 100% boosted is not fitting any
CPU.

This patch makes use of the boosted task utilization just as a threashold
which defines the minimum capacity should be available on a CPU to host that
task.

Signed-off-by: default avatarPatrick Bellasi <patrick.bellasi@arm.com>
parent c50cc229

kernel/sched/fair.c

+8 −1
Original line number Diff line number Diff line
@@ -5636,6 +5636,7 @@ static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync) 
	struct sched_group *sg, *sg_target;

	int target_max_cap = INT_MAX;

	int target_cpu = task_cpu(p);

	unsigned long task_util_boosted, new_util;

	int i;



	if (sysctl_sched_sync_hint_enable && sync) {
@@ -5679,6 +5680,7 @@ static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync) 
			}

		} while (sg = sg->next, sg != sd->groups);



		task_util_boosted = boosted_task_util(p);

		/* Find cpu with sufficient capacity */

		for_each_cpu_and(i, tsk_cpus_allowed(p), sched_group_cpus(sg_target)) {

			/*
@@ -5686,8 +5688,13 @@ static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync) 
			 * so prev_cpu will receive a negative bias due to the double

			 * accounting. However, the blocked utilization may be zero.

			 */

			int new_util = cpu_util(i) + boosted_task_util(p);

			new_util = cpu_util(i) + task_util_boosted;



			/*

			 * Ensure minimum capacity to grant the required boost.

			 * The target CPU can be already at a capacity level higher

			 * than the one required to boost the task.

			 */

			if (new_util > capacity_orig_of(i))

				continue;