lkml.org 
[lkml]   [2020]   [Jul]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4/9] timers: Always keep track of next expiry
Date
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.

We are going to expand that logic beyond nohz in order to spare timers
softirqs so do it unconditionally.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.com>
---
kernel/time/timer.c | 36 +++++++++++++++++++-----------------
1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index acf7cb8c09f8..8a4138e47aa4 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -558,8 +558,22 @@ 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
* then it can't set base->is_idle as we hold the base lock:
*/
- if (!base->is_idle)
- return;
+ if (base->is_idle)
+ wake_up_nohz_cpu(base->cpu);
+}
+
+/*
+ * Enqueue the timer into the hash bucket, mark it pending in
+ * the bitmap and store the index in the timer flags.
+ */
+static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
+ unsigned int idx)
+{
+ hlist_add_head(&timer->entry, base->vectors + idx);
+ __set_bit(idx, base->pending_map);
+ timer_set_idx(timer, idx);
+
+ trace_timer_start(timer, timer->expires, timer->flags);

/* Check whether this is the new first expiring timer: */
if (time_after_eq(timer->expires, base->next_expiry))
@@ -578,21 +592,7 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
} else {
base->next_expiry = timer->expires;
}
- wake_up_nohz_cpu(base->cpu);
-}

-/*
- * Enqueue the timer into the hash bucket, mark it pending in
- * the bitmap and store the index in the timer flags.
- */
-static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
- unsigned int idx)
-{
- hlist_add_head(&timer->entry, base->vectors + idx);
- __set_bit(idx, base->pending_map);
- timer_set_idx(timer, idx);
-
- trace_timer_start(timer, timer->expires, timer->flags);
trigger_dyntick_cpu(base, timer);
}

@@ -1490,7 +1490,6 @@ static int __collect_expired_timers(struct timer_base *base,
return levels;
}

-#ifdef CONFIG_NO_HZ_COMMON
/*
* 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
@@ -1582,6 +1581,7 @@ static unsigned long __next_timer_interrupt(struct timer_base *base)
return next;
}

+#ifdef CONFIG_NO_HZ_COMMON
/*
* Check, if the next hrtimer event is before the next timer wheel
* event:
@@ -1787,6 +1787,7 @@ static inline void __run_timers(struct timer_base *base)

levels = collect_expired_timers(base, heads);
base->clk++;
+ base->next_expiry = __next_timer_interrupt(base);

while (levels--)
expire_timers(base, heads + levels);
@@ -2039,6 +2040,7 @@ static void __init init_timer_cpu(int cpu)
base->cpu = cpu;
raw_spin_lock_init(&base->lock);
base->clk = jiffies;
+ base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
timer_base_init_expiry_lock(base);
}
}
--
2.26.2
\
 
 \ /
  Last update: 2020-07-07 03:40    [W:0.084 / U:2.804 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site