linux-kernel - [PATCH] sched/clock: use static_branch_likely() check at sched_clock

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Date:   Wed, 27 Nov 2019 16:37:28 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        Zhenzhong Duan <zhenzhong.duan@...cle.com>
Subject: [PATCH] sched/clock: use static_branch_likely() check at sched_clock_running

sched_clock_running is enabled early at bootup stage and never
disabled. So hints that to compiler by using static_branch_likely()
rather than static_branch_unlikely().

Fixes: 46457ea464f5 ("sched/clock: Use static key for sched_clock_running")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
---
 kernel/sched/clock.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index 1152259..12bca64 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -370,7 +370,7 @@ u64 sched_clock_cpu(int cpu)
 	if (sched_clock_stable())
 		return sched_clock() + __sched_clock_offset;
 
-	if (!static_branch_unlikely(&sched_clock_running))
+	if (!static_branch_likely(&sched_clock_running))
 		return sched_clock();
 
 	preempt_disable_notrace();
@@ -393,7 +393,7 @@ void sched_clock_tick(void)
 	if (sched_clock_stable())
 		return;
 
-	if (!static_branch_unlikely(&sched_clock_running))
+	if (!static_branch_likely(&sched_clock_running))
 		return;
 
 	lockdep_assert_irqs_disabled();
@@ -460,7 +460,7 @@ void __init sched_clock_init(void)
 
 u64 sched_clock_cpu(int cpu)
 {
-	if (!static_branch_unlikely(&sched_clock_running))
+	if (!static_branch_likely(&sched_clock_running))
 		return 0;
 
 	return sched_clock();
-- 
1.8.3.1