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From:   Qais Yousef <qais.yousef@arm.com>
To:     Ingo Molnar <mingo@kernel.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc:     linux-kernel@vger.kernel.org, Xuewen Yan <xuewen.yan94@gmail.com>,
        Lukasz Luba <lukasz.luba@arm.com>, Wei Wang <wvw@google.com>,
        Jonathan JMChen <Jonathan.JMChen@mediatek.com>,
        Hank <han.lin@mediatek.com>, Qais Yousef <qais.yousef@arm.com>
Subject: [PATCH v2 7/9] sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition
Date:   Thu,  4 Aug 2022 15:36:07 +0100
Message-Id: <20220804143609.515789-8-qais.yousef@arm.com>
In-Reply-To: <20220804143609.515789-1-qais.yousef@arm.com>
References: <20220804143609.515789-1-qais.yousef@arm.com>
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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>
---
 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 4c3a5240d7e3..59ba7106ddc6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4108,14 +4108,16 @@ 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);
 }
@@ -7029,7 +7031,7 @@ 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);
-- 
2.25.1