2 files changed, 68 insertions, 15 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index de0da71daf77..0cc913a8554f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1815,7 +1815,7 @@ static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
 }
 #endif
 
-static void calc_load_account_active(struct rq *this_rq);
+static void calc_load_account_idle(struct rq *this_rq);
 static void update_sysctl(void);
 static int get_update_sysctl_factor(void);
 
@@ -2950,6 +2950,61 @@ static unsigned long calc_load_update;
 unsigned long avenrun[3];
 EXPORT_SYMBOL(avenrun);
 
+static long calc_load_fold_active(struct rq *this_rq)
+{
+        long nr_active, delta = 0;
+
+        nr_active = this_rq->nr_running;
+        nr_active += (long) this_rq->nr_uninterruptible;
+
+        if (nr_active != this_rq->calc_load_active) {
+                delta = nr_active - this_rq->calc_load_active;
+                this_rq->calc_load_active = nr_active;
+        }
+
+        return delta;
+}
+
+#ifdef CONFIG_NO_HZ
+/*
+ * For NO_HZ we delay the active fold to the next LOAD_FREQ update.
+ *
+ * When making the ILB scale, we should try to pull this in as well.
+ */
+static atomic_long_t calc_load_tasks_idle;
+
+static void calc_load_account_idle(struct rq *this_rq)
+{
+        long delta;
+
+        delta = calc_load_fold_active(this_rq);
+        if (delta)
+                atomic_long_add(delta, &calc_load_tasks_idle);
+}
+
+static long calc_load_fold_idle(void)
+{
+        long delta = 0;
+
+        /*
+         * Its got a race, we don't care...
+         */
+        if (atomic_long_read(&calc_load_tasks_idle))
+                delta = atomic_long_xchg(&calc_load_tasks_idle, 0);
+
+        return delta;
+}
+#else
+static void calc_load_account_idle(struct rq *this_rq)
+{
+}
+
+static inline long calc_load_fold_idle(void)
+{
+        return 0;
+}
+#endif
+
 /**
  * get_avenrun - get the load average array
  * @loads:      pointer to dest load array
@@ -2996,20 +3051,22 @@ void calc_global_load(void)
 }
 
 /*
- * Either called from update_cpu_load() or from a cpu going idle
+ * Called from update_cpu_load() to periodically update this CPU's
+ * active count.
  */
 static void calc_load_account_active(struct rq *this_rq)
 {
-        long nr_active, delta;
+        long delta;
 
-        nr_active = this_rq->nr_running;
-        nr_active += (long) this_rq->nr_uninterruptible;
+        if (time_before(jiffies, this_rq->calc_load_update))
+                return;
 
-        if (nr_active != this_rq->calc_load_active) {
-                delta = nr_active - this_rq->calc_load_active;
-                this_rq->calc_load_active = nr_active;
+        delta  = calc_load_fold_active(this_rq);
+        delta += calc_load_fold_idle();
+        if (delta)
                 atomic_long_add(delta, &calc_load_tasks);
-        }
+
+        this_rq->calc_load_update += LOAD_FREQ;
 }
 
 /*
@@ -3041,10 +3098,7 @@ static void update_cpu_load(struct rq *this_rq)
                 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
         }
 
-        if (time_after_eq(jiffies, this_rq->calc_load_update)) {
-                this_rq->calc_load_update += LOAD_FREQ;
-                calc_load_account_active(this_rq);
-        }
+        calc_load_account_active(this_rq);
 }
 
 #ifdef CONFIG_SMP
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index bea2b8f12024..9fa0f402c87c 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -23,8 +23,7 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl
 static struct task_struct *pick_next_task_idle(struct rq *rq)
 {
         schedstat_inc(rq, sched_goidle);
-        /* adjust the active tasks as we might go into a long sleep */
-        calc_load_account_active(rq);
+        calc_load_account_idle(rq);
         return rq->idle;
 }