[tip: sched/core] sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition

[tip-bot2 for Qais Yousef]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     d81304bc6193554014d4372a01debdf65e1e9a4d
Gitweb:        https://git.kernel.org/tip/d81304bc6193554014d4372a01debdf65e1e9a4d
Author:        Qais Yousef <qais.yousef@xxxxxxx>
AuthorDate:    Thu, 04 Aug 2022 15:36:07 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 27 Oct 2022 11:01:19 +02:00

sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition

If the utilization of the woken up task is 0, we skip the energy
calculation because it has no impact.

But if the task is boosted (uclamp_min != 0) will have an impact on task
placement and frequency selection. Only skip if the util is truly
0 after applying uclamp values.

Change uclamp_task_cpu() signature to avoid unnecessary additional calls
to uclamp_eff_get(). feec() is the only user now.

Fixes: 732cd75b8c920 ("sched/fair: Select an energy-efficient CPU on task wake-up")
Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220804143609.515789-8-qais.yousef@xxxxxxx
---
 kernel/sched/fair.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a0ee319..0f32acb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4280,14 +4280,16 @@ static inline unsigned long task_util_est(struct task_struct *p)
 }
 
 #ifdef CONFIG_UCLAMP_TASK
-static inline unsigned long uclamp_task_util(struct task_struct *p)
+static inline unsigned long uclamp_task_util(struct task_struct *p,
+					     unsigned long uclamp_min,
+					     unsigned long uclamp_max)
 {
-	return clamp(task_util_est(p),
-		     uclamp_eff_value(p, UCLAMP_MIN),
-		     uclamp_eff_value(p, UCLAMP_MAX));
+	return clamp(task_util_est(p), uclamp_min, uclamp_max);
 }
 #else
-static inline unsigned long uclamp_task_util(struct task_struct *p)
+static inline unsigned long uclamp_task_util(struct task_struct *p,
+					     unsigned long uclamp_min,
+					     unsigned long uclamp_max)
 {
 	return task_util_est(p);
 }
@@ -7205,7 +7207,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
 	target = prev_cpu;
 
 	sync_entity_load_avg(&p->se);
-	if (!task_util_est(p))
+	if (!uclamp_task_util(p, p_util_min, p_util_max))
 		goto unlock;
 
 	eenv_task_busy_time(&eenv, p, prev_cpu);