nohz: reduce jiffies polling overhead

Signed-off-by: Ingo Molnar <mingo@elte.hu>

nohz: reduce jiffies polling overhead
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Ingo Molnar
1 parent 916941b2bf
Showing 1 changed file with 7 additions and 0 deletions Side-by-side Diff
kernel/time/tick-sched.c
@@ -48,6 +48,13 @@
 	unsigned long ticks = 0;
 	ktime_t delta;
  
+	/*
+	 * Do a quick check without holding xtime_lock:
+	 */
+	delta = ktime_sub(now, last_jiffies_update);
+	if (delta.tv64 < tick_period.tv64)
+		return;
+
 	/* Reevalute with xtime_lock held */
 	write_seqlock(&xtime_lock);
...	...	@@ -48,6 +48,13 @@
48	48	unsigned long ticks = 0;
49	49	ktime_t delta;
50	50
	51	+ /*
	52	+ * Do a quick check without holding xtime_lock:
	53	+ */
	54	+ delta = ktime_sub(now, last_jiffies_update);
	55	+ if (delta.tv64 < tick_period.tv64)
	56	+ return;
	57	+
51	58	/* Reevalute with xtime_lock held */
52	59	write_seqlock(&xtime_lock);
53	60