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From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
	Zhenzhong Duan <zhenzhong.duan@oracle.com>
Subject: [PATCH] sched/clock: use static_branch_likely() check at sched_clock_running
Date: Wed, 27 Nov 2019 16:37:28 +0800	[thread overview]
Message-ID: <1574843848-26825-1-git-send-email-zhenzhong.duan@oracle.com> (raw)

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@oracle.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


             reply	other threads:[~2019-11-27  8:40 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-27  8:37 Zhenzhong Duan [this message]
2019-11-27 15:14 ` Steven Rostedt
2019-11-29  9:59 ` [tip: sched/urgent] sched/clock: Use static_branch_likely() with sched_clock_running tip-bot2 for Zhenzhong Duan

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