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-rw-r--r--kernel/hrtimer.c58
1 files changed, 53 insertions, 5 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index cb8a15c..b675a67 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -43,6 +43,8 @@
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/debugobjects.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
#include <asm/uaccess.h>
@@ -193,12 +195,24 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
* Switch the timer base to the current CPU when possible.
*/
static inline struct hrtimer_clock_base *
-switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base)
+switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
+ int pinned)
{
struct hrtimer_clock_base *new_base;
struct hrtimer_cpu_base *new_cpu_base;
+ int cpu, preferred_cpu = -1;
+
+ cpu = smp_processor_id();
+#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
+ if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) {
+ preferred_cpu = get_nohz_load_balancer();
+ if (preferred_cpu >= 0)
+ cpu = preferred_cpu;
+ }
+#endif
- new_cpu_base = &__get_cpu_var(hrtimer_bases);
+again:
+ new_cpu_base = &per_cpu(hrtimer_bases, cpu);
new_base = &new_cpu_base->clock_base[base->index];
if (base != new_base) {
@@ -218,6 +232,40 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base)
timer->base = NULL;
spin_unlock(&base->cpu_base->lock);
spin_lock(&new_base->cpu_base->lock);
+
+ /* Optimized away for NOHZ=n SMP=n */
+ if (cpu == preferred_cpu) {
+ /* Calculate clock monotonic expiry time */
+#ifdef CONFIG_HIGH_RES_TIMERS
+ ktime_t expires = ktime_sub(hrtimer_get_expires(timer),
+ new_base->offset);
+#else
+ ktime_t expires = hrtimer_get_expires(timer);
+#endif
+
+ /*
+ * Get the next event on target cpu from the
+ * clock events layer.
+ * This covers the highres=off nohz=on case as well.
+ */
+ ktime_t next = clockevents_get_next_event(cpu);
+
+ ktime_t delta = ktime_sub(expires, next);
+
+ /*
+ * We do not migrate the timer when it is expiring
+ * before the next event on the target cpu because
+ * we cannot reprogram the target cpu hardware and
+ * we would cause it to fire late.
+ */
+ if (delta.tv64 < 0) {
+ cpu = smp_processor_id();
+ spin_unlock(&new_base->cpu_base->lock);
+ spin_lock(&base->cpu_base->lock);
+ timer->base = base;
+ goto again;
+ }
+ }
timer->base = new_base;
}
return new_base;
@@ -235,7 +283,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
return base;
}
-# define switch_hrtimer_base(t, b) (b)
+# define switch_hrtimer_base(t, b, p) (b)
#endif /* !CONFIG_SMP */
@@ -907,9 +955,9 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
ret = remove_hrtimer(timer, base);
/* Switch the timer base, if necessary: */
- new_base = switch_hrtimer_base(timer, base);
+ new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
- if (mode == HRTIMER_MODE_REL) {
+ if (mode & HRTIMER_MODE_REL) {
tim = ktime_add_safe(tim, new_base->get_time());
/*
* CONFIG_TIME_LOW_RES is a temporary way for architectures
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