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timers: Always keep track of next expiry

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So far next expiry was only tracked while the CPU was in nohz_idle mode
in order to cope with missing ticks that can't increment the base->clk
periodically anymore.

This logic is going to be expanded beyond nohz in order to spare timer
softirqs so do it unconditionally.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200717140551.29076-8-frederic@kernel.org
This commit is contained in:
Frederic Weisbecker 2020-07-17 16:05:46 +02:00 • committed by Thomas Gleixner
parent 001ec1b392
commit dc2a0f1fb2
1 changed files with 21 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

42
kernel/time/timer.c
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@ -544,8 +544,7 @@ static int calc_wheel_index(unsigned long expires, unsigned long clk,
} }
static void static void
trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer, trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
unsigned long bucket_expiry)
{ {
if (!is_timers_nohz_active()) if (!is_timers_nohz_active())
return; return;
@ -565,23 +564,8 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer,
* timer is not deferrable. If the other CPU is on the way to idle * timer is not deferrable. If the other CPU is on the way to idle
* then it can't set base->is_idle as we hold the base lock: * then it can't set base->is_idle as we hold the base lock:
*/ */
if (!base->is_idle) if (base->is_idle)
return; wake_up_nohz_cpu(base->cpu);
/*
* Check whether this is the new first expiring timer. The
* effective expiry time of the timer is required here
* (bucket_expiry) instead of timer->expires.
*/
if (time_after_eq(bucket_expiry, base->next_expiry))
return;
/*
* Set the next expiry time and kick the CPU so it can reevaluate the
* wheel:
*/
base->next_expiry = bucket_expiry;
wake_up_nohz_cpu(base->cpu);
} }
/* /*
@ -592,12 +576,26 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer,
static void enqueue_timer(struct timer_base *base, struct timer_list *timer, static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
unsigned int idx, unsigned long bucket_expiry) unsigned int idx, unsigned long bucket_expiry)
{ {
hlist_add_head(&timer->entry, base->vectors + idx); hlist_add_head(&timer->entry, base->vectors + idx);
__set_bit(idx, base->pending_map); __set_bit(idx, base->pending_map);
timer_set_idx(timer, idx); timer_set_idx(timer, idx);
trace_timer_start(timer, timer->expires, timer->flags); trace_timer_start(timer, timer->expires, timer->flags);
trigger_dyntick_cpu(base, timer, bucket_expiry);
/*
* Check whether this is the new first expiring timer. The
* effective expiry time of the timer is required here
* (bucket_expiry) instead of timer->expires.
*/
if (time_before(bucket_expiry, base->next_expiry)) {
/*
* Set the next expiry time and kick the CPU so it
* can reevaluate the wheel:
*/
base->next_expiry = bucket_expiry;
trigger_dyntick_cpu(base, timer);
}
} }
static void internal_add_timer(struct timer_base *base, struct timer_list *timer) static void internal_add_timer(struct timer_base *base, struct timer_list *timer)
@ -1493,7 +1491,6 @@ static int __collect_expired_timers(struct timer_base *base,
return levels; return levels;
} }
#ifdef CONFIG_NO_HZ_COMMON
/* /*
* Find the next pending bucket of a level. Search from level start (@offset) * Find the next pending bucket of a level. Search from level start (@offset)
* + @clk upwards and if nothing there, search from start of the level * + @clk upwards and if nothing there, search from start of the level
@ -1585,6 +1582,7 @@ static unsigned long __next_timer_interrupt(struct timer_base *base)
return next; return next;
} }
#ifdef CONFIG_NO_HZ_COMMON
/* /*
* Check, if the next hrtimer event is before the next timer wheel * Check, if the next hrtimer event is before the next timer wheel
* event: * event:
@ -1790,6 +1788,7 @@ static inline void __run_timers(struct timer_base *base)
levels = collect_expired_timers(base, heads); levels = collect_expired_timers(base, heads);
base->clk++; base->clk++;
base->next_expiry = __next_timer_interrupt(base);
while (levels--) while (levels--)
expire_timers(base, heads + levels); expire_timers(base, heads + levels);
@ -2042,6 +2041,7 @@ static void __init init_timer_cpu(int cpu)
base->cpu = cpu; base->cpu = cpu;
raw_spin_lock_init(&base->lock); raw_spin_lock_init(&base->lock);
base->clk = jiffies; base->clk = jiffies;
base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
timer_base_init_expiry_lock(base); timer_base_init_expiry_lock(base);
} }
} }