From 51febc58ca1cfecdc213a000f404423e375b3005 Mon Sep 17 00:00:00 2001
From: Mike Galbraith <efault@gmx.de>
Date: Thu, 11 Mar 2010 17:17:13 +0100
Subject: [PATCH] --- yaml --- r: 191383 b: refs/heads/master c:
 39c0cbe2150cbd848a25ba6cdb271d1ad46818ad h: refs/heads/master i:   191381:
 03d92611fc5e4a3226007471581fbc25a4c55b02   191379:
 435ea04c02c55ad875d413c138fd3ff1e08c38c6   191375:
 16524d549f713a1fe1d81f77991975e1f3861a10 v: v3

---
 [refs]                         |  2 +-
 trunk/include/linux/sched.h    |  6 ++++++
 trunk/kernel/sched.c           | 12 ++++++++++++
 trunk/kernel/time/tick-sched.c |  3 +++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 5f6a29b53cab..12187934018a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 41acab8851a0408c1d5ad6c21a07456f88b54d40
+refs/heads/master: 39c0cbe2150cbd848a25ba6cdb271d1ad46818ad
diff --git a/trunk/include/linux/sched.h b/trunk/include/linux/sched.h
index 8cc863d66477..13efe7dac5fa 100644
--- a/trunk/include/linux/sched.h
+++ b/trunk/include/linux/sched.h
@@ -271,11 +271,17 @@ extern cpumask_var_t nohz_cpu_mask;
 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
 extern int select_nohz_load_balancer(int cpu);
 extern int get_nohz_load_balancer(void);
+extern int nohz_ratelimit(int cpu);
 #else
 static inline int select_nohz_load_balancer(int cpu)
 {
 	return 0;
 }
+
+static inline int nohz_ratelimit(int cpu)
+{
+	return 0;
+}
 #endif
 
 /*
diff --git a/trunk/kernel/sched.c b/trunk/kernel/sched.c
index a4aa071f08f3..60b1bbe2ad1b 100644
--- a/trunk/kernel/sched.c
+++ b/trunk/kernel/sched.c
@@ -492,6 +492,7 @@ struct rq {
 	#define CPU_LOAD_IDX_MAX 5
 	unsigned long cpu_load[CPU_LOAD_IDX_MAX];
 #ifdef CONFIG_NO_HZ
+	u64 nohz_stamp;
 	unsigned char in_nohz_recently;
 #endif
 	/* capture load from *all* tasks on this cpu: */
@@ -1228,6 +1229,17 @@ void wake_up_idle_cpu(int cpu)
 	if (!tsk_is_polling(rq->idle))
 		smp_send_reschedule(cpu);
 }
+
+int nohz_ratelimit(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	u64 diff = rq->clock - rq->nohz_stamp;
+
+	rq->nohz_stamp = rq->clock;
+
+	return diff < (NSEC_PER_SEC / HZ) >> 1;
+}
+
 #endif /* CONFIG_NO_HZ */
 
 static u64 sched_avg_period(void)
diff --git a/trunk/kernel/time/tick-sched.c b/trunk/kernel/time/tick-sched.c
index f992762d7f51..f25735a767af 100644
--- a/trunk/kernel/time/tick-sched.c
+++ b/trunk/kernel/time/tick-sched.c
@@ -262,6 +262,9 @@ void tick_nohz_stop_sched_tick(int inidle)
 		goto end;
 	}
 
+	if (nohz_ratelimit(cpu))
+		goto end;
+
 	ts->idle_calls++;
 	/* Read jiffies and the time when jiffies were updated last */
 	do {