diff options
| author | Pavel Tatashin <pasha.tatashin@oracle.com> | 2018-07-19 16:55:43 -0400 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-20 00:02:43 +0200 |
| commit | 46457ea464f5341d1f9dad8dd213805d45f7f117 (patch) | |
| tree | 316f05b91ec512ef269e8bdd0cc89e7ea062e0f3 /kernel/sched/clock.c | |
| parent | 857baa87b6422bcfb84ed3631d6839920cb5b09d (diff) | |
sched/clock: Use static key for sched_clock_running
sched_clock_running may be read every time sched_clock_cpu() is called.
Yet, this variable is updated only twice during boot, and never changes
again, therefore it is better to make it a static key.
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-25-pasha.tatashin@oracle.com
Diffstat (limited to 'kernel/sched/clock.c')
| -rw-r--r-- | kernel/sched/clock.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 422cd63f8f17..c5c47ad3f386 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -67,7 +67,7 @@ unsigned long long __weak sched_clock(void) } EXPORT_SYMBOL_GPL(sched_clock); -__read_mostly int sched_clock_running; +static DEFINE_STATIC_KEY_FALSE(sched_clock_running); #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK /* @@ -191,7 +191,7 @@ void clear_sched_clock_stable(void) smp_mb(); /* matches sched_clock_init_late() */ - if (sched_clock_running == 2) + if (static_key_count(&sched_clock_running.key) == 2) __clear_sched_clock_stable(); } @@ -215,7 +215,7 @@ void __init sched_clock_init(void) __sched_clock_gtod_offset(); local_irq_restore(flags); - sched_clock_running = 1; + static_branch_inc(&sched_clock_running); /* Now that sched_clock_running is set adjust scd */ local_irq_save(flags); @@ -228,7 +228,7 @@ void __init sched_clock_init(void) */ static int __init sched_clock_init_late(void) { - sched_clock_running = 2; + static_branch_inc(&sched_clock_running); /* * Ensure that it is impossible to not do a static_key update. * @@ -373,7 +373,7 @@ u64 sched_clock_cpu(int cpu) if (sched_clock_stable()) return sched_clock() + __sched_clock_offset; - if (unlikely(!sched_clock_running)) + if (!static_branch_unlikely(&sched_clock_running)) return sched_clock(); preempt_disable_notrace(); @@ -396,7 +396,7 @@ void sched_clock_tick(void) if (sched_clock_stable()) return; - if (unlikely(!sched_clock_running)) + if (!static_branch_unlikely(&sched_clock_running)) return; lockdep_assert_irqs_disabled(); @@ -455,13 +455,13 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); void __init sched_clock_init(void) { - sched_clock_running = 1; + static_branch_inc(&sched_clock_running); generic_sched_clock_init(); } u64 sched_clock_cpu(int cpu) { - if (unlikely(!sched_clock_running)) + if (!static_branch_unlikely(&sched_clock_running)) return 0; return sched_clock(); |