tick: Sched: Restructure code
Get rid of one indentation level. Preparatory patch for a major rework. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Link: http://lkml.kernel.org/r/20150414203502.101563235@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Thomas Gleixner
Родитель
0ff53d0964
Коммит
157d29e101
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@ -611,112 +611,103 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
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}
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}
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/*
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* Do not stop the tick, if we are only one off (or less)
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* or if the cpu is required for RCU:
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*/
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if (!ts->tick_stopped && delta_jiffies <= 1)
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goto out;
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/* Schedule the tick, if we are at least one jiffie off */
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if ((long)delta_jiffies >= 1) {
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/*
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* If this cpu is the one which updates jiffies, then
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* give up the assignment and let it be taken by the
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* cpu which runs the tick timer next, which might be
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* this cpu as well. If we don't drop this here the
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* jiffies might be stale and do_timer() never
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* invoked. Keep track of the fact that it was the one
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* which had the do_timer() duty last. If this cpu is
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* the one which had the do_timer() duty last, we
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* limit the sleep time to the timekeeping
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* max_deferement value which we retrieved
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* above. Otherwise we can sleep as long as we want.
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*/
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if (cpu == tick_do_timer_cpu) {
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tick_do_timer_cpu = TICK_DO_TIMER_NONE;
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ts->do_timer_last = 1;
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} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
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time_delta = KTIME_MAX;
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ts->do_timer_last = 0;
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} else if (!ts->do_timer_last) {
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time_delta = KTIME_MAX;
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}
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#ifdef CONFIG_NO_HZ_FULL
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if (!ts->inidle) {
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time_delta = min(time_delta,
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scheduler_tick_max_deferment());
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}
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#endif
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/*
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* calculate the expiry time for the next timer wheel
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* timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
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* that there is no timer pending or at least extremely
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* far into the future (12 days for HZ=1000). In this
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* case we set the expiry to the end of time.
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*/
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if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
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/*
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* Calculate the time delta for the next timer event.
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* If the time delta exceeds the maximum time delta
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* permitted by the current clocksource then adjust
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* the time delta accordingly to ensure the
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* clocksource does not wrap.
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*/
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time_delta = min_t(u64, time_delta,
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tick_period.tv64 * delta_jiffies);
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}
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if (time_delta < KTIME_MAX)
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expires = ktime_add_ns(last_update, time_delta);
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else
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expires.tv64 = KTIME_MAX;
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/* Skip reprogram of event if its not changed */
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if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
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if ((long)delta_jiffies <= 1) {
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if (!ts->tick_stopped)
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goto out;
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ret = expires;
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/*
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* nohz_stop_sched_tick can be called several times before
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* the nohz_restart_sched_tick is called. This happens when
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* interrupts arrive which do not cause a reschedule. In the
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* first call we save the current tick time, so we can restart
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* the scheduler tick in nohz_restart_sched_tick.
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*/
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if (!ts->tick_stopped) {
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nohz_balance_enter_idle(cpu);
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calc_load_enter_idle();
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ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
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ts->tick_stopped = 1;
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trace_tick_stop(1, " ");
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}
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/*
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* If the expiration time == KTIME_MAX, then
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* in this case we simply stop the tick timer.
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*/
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if (unlikely(expires.tv64 == KTIME_MAX)) {
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
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hrtimer_cancel(&ts->sched_timer);
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if (delta_jiffies == 0) {
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/* Tick is stopped, but required now. Enforce it */
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tick_nohz_restart(ts, now);
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goto out;
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}
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
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hrtimer_start(&ts->sched_timer, expires,
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HRTIMER_MODE_ABS_PINNED);
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else
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tick_program_event(expires, 1);
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} else {
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/* Tick is stopped, but required now. Enforce it */
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tick_nohz_restart(ts, now);
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}
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}
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/*
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* If this cpu is the one which updates jiffies, then give up
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* the assignment and let it be taken by the cpu which runs
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* the tick timer next, which might be this cpu as well. If we
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* don't drop this here the jiffies might be stale and
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* do_timer() never invoked. Keep track of the fact that it
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* was the one which had the do_timer() duty last. If this cpu
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* is the one which had the do_timer() duty last, we limit the
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* sleep time to the timekeeping max_deferement value which we
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* retrieved above. Otherwise we can sleep as long as we want.
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*/
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if (cpu == tick_do_timer_cpu) {
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tick_do_timer_cpu = TICK_DO_TIMER_NONE;
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ts->do_timer_last = 1;
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} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
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time_delta = KTIME_MAX;
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ts->do_timer_last = 0;
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} else if (!ts->do_timer_last) {
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time_delta = KTIME_MAX;
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}
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#ifdef CONFIG_NO_HZ_FULL
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if (!ts->inidle)
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time_delta = min(time_delta, scheduler_tick_max_deferment());
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#endif
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/*
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* calculate the expiry time for the next timer wheel
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* timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that
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* there is no timer pending or at least extremely far into
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* the future (12 days for HZ=1000). In this case we set the
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* expiry to the end of time.
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*/
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if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
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/*
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* Calculate the time delta for the next timer event.
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* If the time delta exceeds the maximum time delta
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* permitted by the current clocksource then adjust
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* the time delta accordingly to ensure the
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* clocksource does not wrap.
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*/
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time_delta = min_t(u64, time_delta,
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tick_period.tv64 * delta_jiffies);
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}
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if (time_delta < KTIME_MAX)
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expires = ktime_add_ns(last_update, time_delta);
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else
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expires.tv64 = KTIME_MAX;
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/* Skip reprogram of event if its not changed */
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if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
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goto out;
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ret = expires;
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/*
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* nohz_stop_sched_tick can be called several times before
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* the nohz_restart_sched_tick is called. This happens when
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* interrupts arrive which do not cause a reschedule. In the
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* first call we save the current tick time, so we can restart
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* the scheduler tick in nohz_restart_sched_tick.
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*/
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if (!ts->tick_stopped) {
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nohz_balance_enter_idle(cpu);
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calc_load_enter_idle();
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ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
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ts->tick_stopped = 1;
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trace_tick_stop(1, " ");
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}
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/*
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* If the expiration time == KTIME_MAX, then
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* in this case we simply stop the tick timer.
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*/
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if (unlikely(expires.tv64 == KTIME_MAX)) {
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
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hrtimer_cancel(&ts->sched_timer);
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goto out;
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}
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
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hrtimer_start(&ts->sched_timer, expires,
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HRTIMER_MODE_ABS_PINNED);
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else
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tick_program_event(expires, 1);
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out:
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ts->next_jiffies = next_jiffies;
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ts->last_jiffies = last_jiffies;
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