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-rw-r--r--kernel/time/tick-sched.c119
1 files changed, 81 insertions, 38 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index a87b0468568..0581c11fe6c 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -20,6 +20,7 @@
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/tick.h>
+#include <linux/module.h>
#include <asm/irq_regs.h>
@@ -75,6 +76,9 @@ static void tick_do_update_jiffies64(ktime_t now)
incr * ticks);
}
do_timer(++ticks);
+
+ /* Keep the tick_next_period variable up to date */
+ tick_next_period = ktime_add(last_jiffies_update, tick_period);
}
write_sequnlock(&xtime_lock);
}
@@ -151,7 +155,7 @@ void tick_nohz_update_jiffies(void)
touch_softlockup_watchdog();
}
-void tick_nohz_stop_idle(int cpu)
+static void tick_nohz_stop_idle(int cpu)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
@@ -187,9 +191,17 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
- *last_update_time = ktime_to_us(ts->idle_lastupdate);
+ if (!tick_nohz_enabled)
+ return -1;
+
+ if (ts->idle_active)
+ *last_update_time = ktime_to_us(ts->idle_lastupdate);
+ else
+ *last_update_time = ktime_to_us(ktime_get());
+
return ktime_to_us(ts->idle_sleeptime);
}
+EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
/**
* tick_nohz_stop_sched_tick - stop the idle tick from the idle task
@@ -221,7 +233,7 @@ void tick_nohz_stop_sched_tick(int inidle)
*/
if (unlikely(!cpu_online(cpu))) {
if (cpu == tick_do_timer_cpu)
- tick_do_timer_cpu = -1;
+ tick_do_timer_cpu = TICK_DO_TIMER_NONE;
}
if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
@@ -258,7 +270,7 @@ void tick_nohz_stop_sched_tick(int inidle)
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
- if (rcu_needs_cpu(cpu))
+ if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu))
delta_jiffies = 1;
/*
* Do not stop the tick, if we are only one off
@@ -303,7 +315,7 @@ void tick_nohz_stop_sched_tick(int inidle)
* invoked.
*/
if (cpu == tick_do_timer_cpu)
- tick_do_timer_cpu = -1;
+ tick_do_timer_cpu = TICK_DO_TIMER_NONE;
ts->idle_sleeps++;
@@ -365,6 +377,32 @@ ktime_t tick_nohz_get_sleep_length(void)
return ts->sleep_length;
}
+static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
+{
+ hrtimer_cancel(&ts->sched_timer);
+ ts->sched_timer.expires = ts->idle_tick;
+
+ while (1) {
+ /* Forward the time to expire in the future */
+ hrtimer_forward(&ts->sched_timer, now, tick_period);
+
+ if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
+ hrtimer_start(&ts->sched_timer,
+ ts->sched_timer.expires,
+ HRTIMER_MODE_ABS);
+ /* Check, if the timer was already in the past */
+ if (hrtimer_active(&ts->sched_timer))
+ break;
+ } else {
+ if (!tick_program_event(ts->sched_timer.expires, 0))
+ break;
+ }
+ /* Update jiffies and reread time */
+ tick_do_update_jiffies64(now);
+ now = ktime_get();
+ }
+}
+
/**
* tick_nohz_restart_sched_tick - restart the idle tick from the idle task
*
@@ -418,28 +456,7 @@ void tick_nohz_restart_sched_tick(void)
*/
ts->tick_stopped = 0;
ts->idle_exittime = now;
- hrtimer_cancel(&ts->sched_timer);
- ts->sched_timer.expires = ts->idle_tick;
-
- while (1) {
- /* Forward the time to expire in the future */
- hrtimer_forward(&ts->sched_timer, now, tick_period);
-
- if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
- hrtimer_start(&ts->sched_timer,
- ts->sched_timer.expires,
- HRTIMER_MODE_ABS);
- /* Check, if the timer was already in the past */
- if (hrtimer_active(&ts->sched_timer))
- break;
- } else {
- if (!tick_program_event(ts->sched_timer.expires, 0))
- break;
- }
- /* Update jiffies and reread time */
- tick_do_update_jiffies64(now);
- now = ktime_get();
- }
+ tick_nohz_restart(ts, now);
local_irq_enable();
}
@@ -468,7 +485,7 @@ static void tick_nohz_handler(struct clock_event_device *dev)
* this duty, then the jiffies update is still serialized by
* xtime_lock.
*/
- if (unlikely(tick_do_timer_cpu == -1))
+ if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
tick_do_timer_cpu = cpu;
/* Check, if the jiffies need an update */
@@ -491,10 +508,6 @@ static void tick_nohz_handler(struct clock_event_device *dev)
update_process_times(user_mode(regs));
profile_tick(CPU_PROFILING);
- /* Do not restart, when we are in the idle loop */
- if (ts->tick_stopped)
- return;
-
while (tick_nohz_reprogram(ts, now)) {
now = ktime_get();
tick_do_update_jiffies64(now);
@@ -540,6 +553,27 @@ static void tick_nohz_switch_to_nohz(void)
smp_processor_id());
}
+/*
+ * When NOHZ is enabled and the tick is stopped, we need to kick the
+ * tick timer from irq_enter() so that the jiffies update is kept
+ * alive during long running softirqs. That's ugly as hell, but
+ * correctness is key even if we need to fix the offending softirq in
+ * the first place.
+ *
+ * Note, this is different to tick_nohz_restart. We just kick the
+ * timer and do not touch the other magic bits which need to be done
+ * when idle is left.
+ */
+static void tick_nohz_kick_tick(int cpu)
+{
+ struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+
+ if (!ts->tick_stopped)
+ return;
+
+ tick_nohz_restart(ts, ktime_get());
+}
+
#else
static inline void tick_nohz_switch_to_nohz(void) { }
@@ -547,6 +581,19 @@ static inline void tick_nohz_switch_to_nohz(void) { }
#endif /* NO_HZ */
/*
+ * Called from irq_enter to notify about the possible interruption of idle()
+ */
+void tick_check_idle(int cpu)
+{
+ tick_check_oneshot_broadcast(cpu);
+#ifdef CONFIG_NO_HZ
+ tick_nohz_stop_idle(cpu);
+ tick_nohz_update_jiffies();
+ tick_nohz_kick_tick(cpu);
+#endif
+}
+
+/*
* High resolution timer specific code
*/
#ifdef CONFIG_HIGH_RES_TIMERS
@@ -570,7 +617,7 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
* this duty, then the jiffies update is still serialized by
* xtime_lock.
*/
- if (unlikely(tick_do_timer_cpu == -1))
+ if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
tick_do_timer_cpu = cpu;
#endif
@@ -599,10 +646,6 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
profile_tick(CPU_PROFILING);
}
- /* Do not restart, when we are in the idle loop */
- if (ts->tick_stopped)
- return HRTIMER_NORESTART;
-
hrtimer_forward(timer, now, tick_period);
return HRTIMER_RESTART;
@@ -622,7 +665,7 @@ void tick_setup_sched_timer(void)
*/
hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
ts->sched_timer.function = tick_sched_timer;
- ts->sched_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
+ ts->sched_timer.cb_mode = HRTIMER_CB_IRQSAFE_PERCPU;
/* Get the next period (per cpu) */
ts->sched_timer.expires = tick_init_jiffy_update();