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Subject[patch 19/39] 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>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>

---
kernel/time/tick-sched.c | 173 ++++++++++++++++++++++-------------------------
1 file changed, 82 insertions(+), 91 deletions(-)

Index: tip/kernel/time/tick-sched.c
===================================================================
--- tip.orig/kernel/time/tick-sched.c
+++ tip/kernel/time/tick-sched.c
@@ -611,112 +611,103 @@ static ktime_t tick_nohz_stop_sched_tick
}
}

+ if ((long)delta_jiffies <= 1) {
+ if (!ts->tick_stopped)
+ goto out;
+ if (delta_jiffies == 0) {
+ /* Tick is stopped, but required now. Enforce it */
+ tick_nohz_restart(ts, now);
+ goto out;
+ }
+ }
+
/*
- * Do not stop the tick, if we are only one off (or less)
- * or if the cpu is required for RCU:
+ * If this cpu is the one which updates jiffies, then give up
+ * the assignment and let it be taken by the cpu which runs
+ * the tick timer next, which might be this cpu as well. If we
+ * don't drop this here the jiffies might be stale and
+ * do_timer() never invoked. Keep track of the fact that it
+ * was the one which had the do_timer() duty last. If this cpu
+ * is the one which had the do_timer() duty last, we limit the
+ * sleep time to the timekeeping max_deferement value which we
+ * retrieved above. Otherwise we can sleep as long as we want.
*/
- if (!ts->tick_stopped && delta_jiffies <= 1)
- goto out;
-
- /* Schedule the tick, if we are at least one jiffie off */
- if ((long)delta_jiffies >= 1) {
-
- /*
- * If this cpu is the one which updates jiffies, then
- * give up the assignment and let it be taken by the
- * cpu which runs the tick timer next, which might be
- * this cpu as well. If we don't drop this here the
- * jiffies might be stale and do_timer() never
- * invoked. Keep track of the fact that it was the one
- * which had the do_timer() duty last. If this cpu is
- * the one which had the do_timer() duty last, we
- * limit the sleep time to the timekeeping
- * max_deferement value which we retrieved
- * above. Otherwise we can sleep as long as we want.
- */
- if (cpu == tick_do_timer_cpu) {
- tick_do_timer_cpu = TICK_DO_TIMER_NONE;
- ts->do_timer_last = 1;
- } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
- time_delta = KTIME_MAX;
- ts->do_timer_last = 0;
- } else if (!ts->do_timer_last) {
- time_delta = KTIME_MAX;
- }
+ if (cpu == tick_do_timer_cpu) {
+ tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+ ts->do_timer_last = 1;
+ } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
+ time_delta = KTIME_MAX;
+ ts->do_timer_last = 0;
+ } else if (!ts->do_timer_last) {
+ time_delta = KTIME_MAX;
+ }

#ifdef CONFIG_NO_HZ_FULL
- if (!ts->inidle) {
- time_delta = min(time_delta,
- scheduler_tick_max_deferment());
- }
+ if (!ts->inidle)
+ time_delta = min(time_delta, scheduler_tick_max_deferment());
#endif

+ /*
+ * 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 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.
+ * 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.
*/
- 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);
- }
-
- if (time_delta < KTIME_MAX)
- expires = ktime_add_ns(last_update, time_delta);
- else
- expires.tv64 = KTIME_MAX;
+ time_delta = min_t(u64, time_delta,
+ tick_period.tv64 * delta_jiffies);
+ }

- /* Skip reprogram of event if its not changed */
- if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
- goto out;
+ if (time_delta < KTIME_MAX)
+ expires = ktime_add_ns(last_update, time_delta);
+ else
+ expires.tv64 = KTIME_MAX;

- ret = expires;
+ /* Skip reprogram of event if its not changed */
+ if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
+ goto out;

- /*
- * nohz_stop_sched_tick can be called several times before
- * the nohz_restart_sched_tick is called. This happens when
- * interrupts arrive which do not cause a reschedule. In the
- * first call we save the current tick time, so we can restart
- * the scheduler tick in nohz_restart_sched_tick.
- */
- if (!ts->tick_stopped) {
- nohz_balance_enter_idle(cpu);
- calc_load_enter_idle();
-
- ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
- ts->tick_stopped = 1;
- trace_tick_stop(1, " ");
- }
+ ret = expires;

- /*
- * If the expiration time == KTIME_MAX, then
- * in this case we simply stop the tick timer.
- */
- if (unlikely(expires.tv64 == KTIME_MAX)) {
- if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
- hrtimer_cancel(&ts->sched_timer);
- goto out;
- }
+ /*
+ * nohz_stop_sched_tick can be called several times before
+ * the nohz_restart_sched_tick is called. This happens when
+ * interrupts arrive which do not cause a reschedule. In the
+ * first call we save the current tick time, so we can restart
+ * the scheduler tick in nohz_restart_sched_tick.
+ */
+ if (!ts->tick_stopped) {
+ nohz_balance_enter_idle(cpu);
+ calc_load_enter_idle();
+
+ ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
+ ts->tick_stopped = 1;
+ trace_tick_stop(1, " ");
+ }

- if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
- hrtimer_start(&ts->sched_timer, expires,
- HRTIMER_MODE_ABS_PINNED);
- else
- tick_program_event(expires, 1);
- } else {
- /* Tick is stopped, but required now. Enforce it */
- tick_nohz_restart(ts, now);
+ /*
+ * If the expiration time == KTIME_MAX, then
+ * in this case we simply stop the tick timer.
+ */
+ if (unlikely(expires.tv64 == KTIME_MAX)) {
+ if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
+ hrtimer_cancel(&ts->sched_timer);
+ goto out;
}

+ if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
+ hrtimer_start(&ts->sched_timer, expires,
+ HRTIMER_MODE_ABS_PINNED);
+ else
+ tick_program_event(expires, 1);
out:
ts->next_jiffies = next_jiffies;
ts->last_jiffies = last_jiffies;



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