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Groups > linux.kernel > #1420602

[patch 19/20] timer: Split out index calculation

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From: Anna-Maria Gleixner <anna-maria@linutronix.de>

For further optimizations we need to seperate index calculation and
queueing. No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/time/timer.c |   41 +++++++++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 8 deletions(-)

--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -456,12 +456,9 @@ static inline unsigned calc_index(unsign
 	return base + (((expires + gran) >> sft) & LVL_MASK);
 }
 
-static void
-__internal_add_timer(struct timer_base *base, struct timer_list *timer)
+static int calc_wheel_index(unsigned long expires, unsigned long clk)
 {
-	unsigned long expires = timer->expires;
-	unsigned long delta = expires - base->clk;
-	struct hlist_head *vec;
+	unsigned long delta = expires - clk;
 	unsigned int idx;
 
 	if (delta < LVL1_TSTART) {
@@ -475,7 +472,7 @@ static void
 	} else if (delta < LVL5_TSTART) {
 		idx = calc_index(expires, LVL4_GRAN, LVL4_SHIFT, LVL4_OFFS);
 	} else if ((long) delta < 0) {
-		idx = base->clk & LVL_MASK;
+		idx = clk & LVL_MASK;
 	} else {
 		/*
 		 * The long timeouts go into the last array level. They
@@ -485,6 +482,18 @@ static void
 		idx = calc_index(expires, LVL5_GRAN, LVL5_SHIFT, LVL5_OFFS);
 	}
 
+	return idx;
+}
+
+/*
+ * 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)
+{
+	struct hlist_head *vec;
+
 	/*
 	 * Enqueue the timer into the array bucket, mark it pending in
 	 * the bitmap and store the index in the timer flags.
@@ -495,10 +504,19 @@ static void
 	timer_set_idx(timer, idx);
 }
 
-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)
 {
-	__internal_add_timer(base, timer);
+	unsigned long expires = timer->expires;
+	unsigned int idx;
+
+	idx = calc_wheel_index(expires, base->clk);
+	enqueue_timer(base, timer, idx);
+}
 
+static void
+trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
+{
 	/*
 	 * We might have to IPI the remote CPU if the base is idle and the
 	 * timer is not deferrable. If the other cpu is on the way to idle
@@ -523,6 +541,13 @@ static void internal_add_timer(struct ti
 		wake_up_nohz_cpu(base->cpu);
 }
 
+static void
+internal_add_timer(struct timer_base *base, struct timer_list *timer)
+{
+	__internal_add_timer(base, timer);
+	trigger_dyntick_cpu(base, timer);
+}
+
 #ifdef CONFIG_TIMER_STATS
 void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
 {

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[patch 19/20] timer: Split out index calculation Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200

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