From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Anna-Maria Behnsen <anna-maria@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>
Subject: [PATCH 07/12] timers: Always keep track of next expiry
Date: Fri, 17 Jul 2020 16:05:46 +0200 [thread overview]
Message-ID: <20200717140551.29076-8-frederic@kernel.org> (raw)
In-Reply-To: <20200717140551.29076-1-frederic@kernel.org>
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.
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.com>
---
kernel/time/timer.c | 42 +++++++++++++++++++++---------------------
1 file changed, 21 insertions(+), 21 deletions(-)
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 9abc41715fd2..76fd9644638b 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -544,8 +544,7 @@ static int calc_wheel_index(unsigned long expires, unsigned long clk,
}
static void
-trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer,
- unsigned long bucket_expiry)
+trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
{
if (!is_timers_nohz_active())
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
* then it can't set base->is_idle as we hold the base lock:
*/
- if (!base->is_idle)
- return;
-
- /*
- * 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);
+ if (base->is_idle)
+ 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,
unsigned int idx, unsigned long bucket_expiry)
{
+
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, 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)
@@ -1493,7 +1491,6 @@ 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
@@ -1585,6 +1582,7 @@ 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:
@@ -1790,6 +1788,7 @@ 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);
@@ -2042,6 +2041,7 @@ 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
next prev parent reply other threads:[~2020-07-17 14:06 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 14:05 [PATCH 00/11] timer: Reduce timers softirq v3 Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 01/12] timer: Fix wheel index calculation on last level Frederic Weisbecker
2020-07-17 19:49 ` [tip: timers/urgent] " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 02/12] timer: Preserve higher bits of expiration on index calculation Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 03/12] timers: Use only bucket expiry for base->next_expiry value Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] " tip-bot2 for Anna-Maria Behnsen
2020-07-17 14:05 ` [PATCH 04/12] timer: Move trigger_dyntick_cpu() to enqueue_timer() Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 05/12] timer: Add comments about calc_index() ceiling work Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 06/12] timer: Optimize _next_timer_interrupt() level iteration Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` Frederic Weisbecker [this message]
2020-07-17 20:00 ` [tip: timers/core] timers: Always keep track of next expiry tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 08/12] timer: Reuse next expiry cache after nohz exit Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 09/12] timer: Expand clk forward logic beyond nohz Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 10/12] timer: Spare timer softirq until next expiry Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 11/12] timer: Remove must_forward_clk Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
2020-07-17 14:05 ` [PATCH 12/12] timer: Lower base clock forwarding threshold Frederic Weisbecker
2020-07-17 20:00 ` [tip: timers/core] timers: " tip-bot2 for Frederic Weisbecker
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