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

[ Upstream commit d81304bc6193554014d4372a01debdf65e1e9a4d ]

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@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220804143609.515789-8-qais.yousef@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a0ee319..0f32acb 100644 (file)
--- 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);