summaryrefslogtreecommitdiffstats
path: root/kernel/time/tick-sched.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/time/tick-sched.c')
-rw-r--r--kernel/time/tick-sched.c52
1 files changed, 38 insertions, 14 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index c65ba0faa98..a80b4644fe6 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -208,6 +208,7 @@ void tick_nohz_stop_sched_tick(int inidle)
struct tick_sched *ts;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+ u64 time_delta;
int cpu;
local_irq_save(flags);
@@ -262,6 +263,17 @@ void tick_nohz_stop_sched_tick(int inidle)
seq = read_seqbegin(&xtime_lock);
last_update = last_jiffies_update;
last_jiffies = jiffies;
+
+ /*
+ * On SMP we really should only care for the CPU which
+ * has the do_timer duty assigned. All other CPUs can
+ * sleep as long as they want.
+ */
+ if (cpu == tick_do_timer_cpu ||
+ tick_do_timer_cpu == TICK_DO_TIMER_NONE)
+ time_delta = timekeeping_max_deferment();
+ else
+ time_delta = KTIME_MAX;
} while (read_seqretry(&xtime_lock, seq));
if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
@@ -284,11 +296,26 @@ void tick_nohz_stop_sched_tick(int inidle)
if ((long)delta_jiffies >= 1) {
/*
- * calculate the expiry time for the next timer wheel
- * timer
- */
- expires = ktime_add_ns(last_update, tick_period.tv64 *
- delta_jiffies);
+ * calculate the expiry time for the next timer wheel
+ * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
+ * that there is no timer pending or at least extremely
+ * far into the future (12 days for HZ=1000). In this
+ * case we set the expiry to the end of time.
+ */
+ if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
+ /*
+ * Calculate the time delta for the next timer event.
+ * If the time delta exceeds the maximum time delta
+ * permitted by the current clocksource then adjust
+ * the time delta accordingly to ensure the
+ * clocksource does not wrap.
+ */
+ time_delta = min_t(u64, time_delta,
+ tick_period.tv64 * delta_jiffies);
+ expires = ktime_add_ns(last_update, time_delta);
+ } else {
+ expires.tv64 = KTIME_MAX;
+ }
/*
* If this cpu is the one which updates jiffies, then
@@ -332,22 +359,19 @@ void tick_nohz_stop_sched_tick(int inidle)
ts->idle_sleeps++;
+ /* Mark expires */
+ ts->idle_expires = expires;
+
/*
- * delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that
- * there is no timer pending or at least extremly far
- * into the future (12 days for HZ=1000). In this case
- * we simply stop the tick timer:
+ * If the expiration time == KTIME_MAX, then
+ * in this case we simply stop the tick timer.
*/
- if (unlikely(delta_jiffies >= NEXT_TIMER_MAX_DELTA)) {
- ts->idle_expires.tv64 = KTIME_MAX;
+ if (unlikely(expires.tv64 == KTIME_MAX)) {
if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
hrtimer_cancel(&ts->sched_timer);
goto out;
}
- /* Mark expiries */
- ts->idle_expires = expires;
-
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
HRTIMER_MODE_ABS_PINNED);