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Diffstat (limited to 'kernel/time/hrtimer.c')
-rw-r--r--kernel/time/hrtimer.c36
1 files changed, 22 insertions, 14 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 5c7ae4b..457a373 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -183,7 +183,7 @@ struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
int pinned)
{
if (pinned || !base->migration_enabled)
- return this_cpu_ptr(&hrtimer_bases);
+ return base;
return &per_cpu(hrtimer_bases, get_nohz_timer_target());
}
#else
@@ -191,23 +191,32 @@ static inline
struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
int pinned)
{
- return this_cpu_ptr(&hrtimer_bases);
+ return base;
}
#endif
/*
- * Switch the timer base to the current CPU when possible.
+ * We switch the timer base to a power-optimized selected CPU target,
+ * if:
+ * - NO_HZ_COMMON is enabled
+ * - timer migration is enabled
+ * - the timer callback is not running
+ * - the timer is not the first expiring timer on the new target
+ *
+ * If one of the above requirements is not fulfilled we move the timer
+ * to the current CPU or leave it on the previously assigned CPU if
+ * the timer callback is currently running.
*/
static inline struct hrtimer_clock_base *
switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
int pinned)
{
- struct hrtimer_cpu_base *new_cpu_base, *this_base;
+ struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
struct hrtimer_clock_base *new_base;
int basenum = base->index;
- this_base = this_cpu_ptr(&hrtimer_bases);
- new_cpu_base = get_target_base(this_base, pinned);
+ this_cpu_base = this_cpu_ptr(&hrtimer_bases);
+ new_cpu_base = get_target_base(this_cpu_base, pinned);
again:
new_base = &new_cpu_base->clock_base[basenum];
@@ -229,19 +238,19 @@ again:
raw_spin_unlock(&base->cpu_base->lock);
raw_spin_lock(&new_base->cpu_base->lock);
- if (new_cpu_base != this_base &&
+ if (new_cpu_base != this_cpu_base &&
hrtimer_check_target(timer, new_base)) {
raw_spin_unlock(&new_base->cpu_base->lock);
raw_spin_lock(&base->cpu_base->lock);
- new_cpu_base = this_base;
+ new_cpu_base = this_cpu_base;
timer->base = base;
goto again;
}
timer->base = new_base;
} else {
- if (new_cpu_base != this_base &&
+ if (new_cpu_base != this_cpu_base &&
hrtimer_check_target(timer, new_base)) {
- new_cpu_base = this_base;
+ new_cpu_base = this_cpu_base;
goto again;
}
}
@@ -679,14 +688,14 @@ static void retrigger_next_event(void *arg)
/*
* Switch to high resolution mode
*/
-static int hrtimer_switch_to_hres(void)
+static void hrtimer_switch_to_hres(void)
{
struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
if (tick_init_highres()) {
printk(KERN_WARNING "Could not switch to high resolution "
"mode on CPU %d\n", base->cpu);
- return 0;
+ return;
}
base->hres_active = 1;
hrtimer_resolution = HIGH_RES_NSEC;
@@ -694,7 +703,6 @@ static int hrtimer_switch_to_hres(void)
tick_setup_sched_timer();
/* "Retrigger" the interrupt to get things going */
retrigger_next_event(NULL);
- return 1;
}
static void clock_was_set_work(struct work_struct *work)
@@ -718,7 +726,7 @@ void clock_was_set_delayed(void)
static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *b) { return 0; }
static inline int hrtimer_hres_active(void) { return 0; }
static inline int hrtimer_is_hres_enabled(void) { return 0; }
-static inline int hrtimer_switch_to_hres(void) { return 0; }
+static inline void hrtimer_switch_to_hres(void) { }
static inline void
hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
static inline int hrtimer_reprogram(struct hrtimer *timer,