sched: Rate-limit nohz

LeeDroid- · Sep 17, 2011 · ad2d036 · ad2d036
1 parent ebc6028
commit ad2d036
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Showing 3 changed files with 20 additions and 0 deletions.
diff --git a/include/linux/sched.h b/include/linux/sched.h
@@ -274,11 +274,17 @@ 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/kernel/sched.c b/kernel/sched.c
@@ -1244,6 +1244,17 @@ void wake_up_idle_cpu(int cpu)
 		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/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
@@ -315,6 +315,9 @@ 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 {