+ rq->next_balance = next_balance;
+}
+
+/*
+ * run_rebalance_domains is triggered when needed from the scheduler tick.
+ * In CONFIG_NO_HZ case, the idle load balance owner will do the
+ * rebalancing for all the cpus for whom scheduler ticks are stopped.
+ */
+static void run_rebalance_domains(struct softirq_action *h)
+{
+ int local_cpu = smp_processor_id();
+ struct rq *local_rq = cpu_rq(local_cpu);
+ enum idle_type idle = local_rq->idle_at_tick ? SCHED_IDLE : NOT_IDLE;
+
+ rebalance_domains(local_cpu, idle);
+
+#ifdef CONFIG_NO_HZ
+ /*
+ * If this cpu is the owner for idle load balancing, then do the
+ * balancing on behalf of the other idle cpus whose ticks are
+ * stopped.
+ */
+ if (local_rq->idle_at_tick &&
+ atomic_read(&nohz.load_balancer) == local_cpu) {
+ cpumask_t cpus = nohz.cpu_mask;
+ struct rq *rq;
+ int balance_cpu;
+
+ cpu_clear(local_cpu, cpus);
+ for_each_cpu_mask(balance_cpu, cpus) {
+ /*
+ * If this cpu gets work to do, stop the load balancing
+ * work being done for other cpus. Next load
+ * balancing owner will pick it up.
+ */
+ if (need_resched())
+ break;
+
+ rebalance_domains(balance_cpu, SCHED_IDLE);
+
+ rq = cpu_rq(balance_cpu);
+ if (time_after(local_rq->next_balance, rq->next_balance))
+ local_rq->next_balance = rq->next_balance;
+ }
+ }
+#endif
+}
+
+/*
+ * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
+ *
+ * In case of CONFIG_NO_HZ, this is the place where we nominate a new
+ * idle load balancing owner or decide to stop the periodic load balancing,
+ * if the whole system is idle.
+ */
+static inline void trigger_load_balance(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+#ifdef CONFIG_NO_HZ
+ /*
+ * If we were in the nohz mode recently and busy at the current
+ * scheduler tick, then check if we need to nominate new idle
+ * load balancer.
+ */
+ if (rq->in_nohz_recently && !rq->idle_at_tick) {
+ rq->in_nohz_recently = 0;
+
+ if (atomic_read(&nohz.load_balancer) == cpu) {
+ cpu_clear(cpu, nohz.cpu_mask);
+ atomic_set(&nohz.load_balancer, -1);
+ }
+
+ if (atomic_read(&nohz.load_balancer) == -1) {
+ /*
+ * simple selection for now: Nominate the
+ * first cpu in the nohz list to be the next
+ * ilb owner.
+ *
+ * TBD: Traverse the sched domains and nominate
+ * the nearest cpu in the nohz.cpu_mask.
+ */
+ int ilb = first_cpu(nohz.cpu_mask);
+
+ if (ilb != NR_CPUS)
+ resched_cpu(ilb);
+ }
+ }
+
+ /*
+ * If this cpu is idle and doing idle load balancing for all the
+ * cpus with ticks stopped, is it time for that to stop?
+ */
+ if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
+ cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
+ resched_cpu(cpu);
+ return;
+ }
+
+ /*
+ * If this cpu is idle and the idle load balancing is done by
+ * someone else, then no need raise the SCHED_SOFTIRQ
+ */
+ if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
+ cpu_isset(cpu, nohz.cpu_mask))
+ return;
+#endif
+ if (time_after_eq(jiffies, rq->next_balance))
+ raise_softirq(SCHED_SOFTIRQ);