1 files changed, 1023 insertions, 89 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 9ba3daa03475..274b40d7bef2 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -3,6 +3,217 @@
  * policies)
  */
 
+#ifdef CONFIG_SMP
+
+static inline int rt_overloaded(struct rq *rq)
+{
+        return atomic_read(&rq->rd->rto_count);
+}
+
+static inline void rt_set_overload(struct rq *rq)
+{
+        cpu_set(rq->cpu, rq->rd->rto_mask);
+        /*
+         * Make sure the mask is visible before we set
+         * the overload count. That is checked to determine
+         * if we should look at the mask. It would be a shame
+         * if we looked at the mask, but the mask was not
+         * updated yet.
+         */
+        wmb();
+        atomic_inc(&rq->rd->rto_count);
+}
+
+static inline void rt_clear_overload(struct rq *rq)
+{
+        /* the order here really doesn't matter */
+        atomic_dec(&rq->rd->rto_count);
+        cpu_clear(rq->cpu, rq->rd->rto_mask);
+}
+
+static void update_rt_migration(struct rq *rq)
+{
+        if (rq->rt.rt_nr_migratory && (rq->rt.rt_nr_running > 1)) {
+                if (!rq->rt.overloaded) {
+                        rt_set_overload(rq);
+                        rq->rt.overloaded = 1;
+                }
+        } else if (rq->rt.overloaded) {
+                rt_clear_overload(rq);
+                rq->rt.overloaded = 0;
+        }
+}
+#endif /* CONFIG_SMP */
+
+static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
+{
+        return container_of(rt_se, struct task_struct, rt);
+}
+
+static inline int on_rt_rq(struct sched_rt_entity *rt_se)
+{
+        return !list_empty(&rt_se->run_list);
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+static inline unsigned int sched_rt_ratio(struct rt_rq *rt_rq)
+{
+        if (!rt_rq->tg)
+                return SCHED_RT_FRAC;
+
+        return rt_rq->tg->rt_ratio;
+}
+
+#define for_each_leaf_rt_rq(rt_rq, rq) \
+        list_for_each_entry(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
+
+static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
+{
+        return rt_rq->rq;
+}
+
+static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
+{
+        return rt_se->rt_rq;
+}
+
+#define for_each_sched_rt_entity(rt_se) \
+        for (; rt_se; rt_se = rt_se->parent)
+
+static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
+{
+        return rt_se->my_q;
+}
+
+static void enqueue_rt_entity(struct sched_rt_entity *rt_se);
+static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
+
+static void sched_rt_ratio_enqueue(struct rt_rq *rt_rq)
+{
+        struct sched_rt_entity *rt_se = rt_rq->rt_se;
+
+        if (rt_se && !on_rt_rq(rt_se) && rt_rq->rt_nr_running) {
+                struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
+
+                enqueue_rt_entity(rt_se);
+                if (rt_rq->highest_prio < curr->prio)
+                        resched_task(curr);
+        }
+}
+
+static void sched_rt_ratio_dequeue(struct rt_rq *rt_rq)
+{
+        struct sched_rt_entity *rt_se = rt_rq->rt_se;
+
+        if (rt_se && on_rt_rq(rt_se))
+                dequeue_rt_entity(rt_se);
+}
+
+#else
+
+static inline unsigned int sched_rt_ratio(struct rt_rq *rt_rq)
+{
+        return sysctl_sched_rt_ratio;
+}
+
+#define for_each_leaf_rt_rq(rt_rq, rq) \
+        for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
+
+static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
+{
+        return container_of(rt_rq, struct rq, rt);
+}
+
+static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
+{
+        struct task_struct *p = rt_task_of(rt_se);
+        struct rq *rq = task_rq(p);
+
+        return &rq->rt;
+}
+
+#define for_each_sched_rt_entity(rt_se) \
+        for (; rt_se; rt_se = NULL)
+
+static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
+{
+        return NULL;
+}
+
+static inline void sched_rt_ratio_enqueue(struct rt_rq *rt_rq)
+{
+}
+
+static inline void sched_rt_ratio_dequeue(struct rt_rq *rt_rq)
+{
+}
+
+#endif
+
+static inline int rt_se_prio(struct sched_rt_entity *rt_se)
+{
+#ifdef CONFIG_FAIR_GROUP_SCHED
+        struct rt_rq *rt_rq = group_rt_rq(rt_se);
+
+        if (rt_rq)
+                return rt_rq->highest_prio;
+#endif
+
+        return rt_task_of(rt_se)->prio;
+}
+
+static int sched_rt_ratio_exceeded(struct rt_rq *rt_rq)
+{
+        unsigned int rt_ratio = sched_rt_ratio(rt_rq);
+        u64 period, ratio;
+
+        if (rt_ratio == SCHED_RT_FRAC)
+                return 0;
+
+        if (rt_rq->rt_throttled)
+                return 1;
+
+        period = (u64)sysctl_sched_rt_period * NSEC_PER_MSEC;
+        ratio = (period * rt_ratio) >> SCHED_RT_FRAC_SHIFT;
+
+        if (rt_rq->rt_time > ratio) {
+                struct rq *rq = rq_of_rt_rq(rt_rq);
+
+                rq->rt_throttled = 1;
+                rt_rq->rt_throttled = 1;
+
+                sched_rt_ratio_dequeue(rt_rq);
+                return 1;
+        }
+
+        return 0;
+}
+
+static void update_sched_rt_period(struct rq *rq)
+{
+        struct rt_rq *rt_rq;
+        u64 period;
+
+        while (rq->clock > rq->rt_period_expire) {
+                period = (u64)sysctl_sched_rt_period * NSEC_PER_MSEC;
+                rq->rt_period_expire += period;
+
+                for_each_leaf_rt_rq(rt_rq, rq) {
+                        unsigned long rt_ratio = sched_rt_ratio(rt_rq);
+                        u64 ratio = (period * rt_ratio) >> SCHED_RT_FRAC_SHIFT;
+
+                        rt_rq->rt_time -= min(rt_rq->rt_time, ratio);
+                        if (rt_rq->rt_throttled) {
+                                rt_rq->rt_throttled = 0;
+                                sched_rt_ratio_enqueue(rt_rq);
+                        }
+                }
+
+                rq->rt_throttled = 0;
+        }
+}
+
 /*
  * Update the current task's runtime statistics. Skip current tasks that
  * are not in our scheduling class.
@@ -10,6 +221,8 @@
 static void update_curr_rt(struct rq *rq)
 {
         struct task_struct *curr = rq->curr;
+        struct sched_rt_entity *rt_se = &curr->rt;
+        struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
         u64 delta_exec;
 
         if (!task_has_rt_policy(curr))
@@ -24,47 +237,228 @@ static void update_curr_rt(struct rq *rq)
         curr->se.sum_exec_runtime += delta_exec;
         curr->se.exec_start = rq->clock;
         cpuacct_charge(curr, delta_exec);
+
+        rt_rq->rt_time += delta_exec;
+        /*
+         * might make it a tad more accurate:
+         *
+         * update_sched_rt_period(rq);
+         */
+        if (sched_rt_ratio_exceeded(rt_rq))
+                resched_task(curr);
 }
 
-static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
+static inline
+void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
+{
+        WARN_ON(!rt_prio(rt_se_prio(rt_se)));
+        rt_rq->rt_nr_running++;
+#if defined CONFIG_SMP || defined CONFIG_FAIR_GROUP_SCHED
+        if (rt_se_prio(rt_se) < rt_rq->highest_prio)
+                rt_rq->highest_prio = rt_se_prio(rt_se);
+#endif
+#ifdef CONFIG_SMP
+        if (rt_se->nr_cpus_allowed > 1) {
+                struct rq *rq = rq_of_rt_rq(rt_rq);
+                rq->rt.rt_nr_migratory++;
+        }
+
+        update_rt_migration(rq_of_rt_rq(rt_rq));
+#endif
+}
+
+static inline
+void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
+{
+        WARN_ON(!rt_prio(rt_se_prio(rt_se)));
+        WARN_ON(!rt_rq->rt_nr_running);
+        rt_rq->rt_nr_running--;
+#if defined CONFIG_SMP || defined CONFIG_FAIR_GROUP_SCHED
+        if (rt_rq->rt_nr_running) {
+                struct rt_prio_array *array;
+
+                WARN_ON(rt_se_prio(rt_se) < rt_rq->highest_prio);
+                if (rt_se_prio(rt_se) == rt_rq->highest_prio) {
+                        /* recalculate */
+                        array = &rt_rq->active;
+                        rt_rq->highest_prio =
+                                sched_find_first_bit(array->bitmap);
+                } /* otherwise leave rq->highest prio alone */
+        } else
+                rt_rq->highest_prio = MAX_RT_PRIO;
+#endif
+#ifdef CONFIG_SMP
+        if (rt_se->nr_cpus_allowed > 1) {
+                struct rq *rq = rq_of_rt_rq(rt_rq);
+                rq->rt.rt_nr_migratory--;
+        }
+
+        update_rt_migration(rq_of_rt_rq(rt_rq));
+#endif /* CONFIG_SMP */
+}
+
+static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
+{
+        struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
+        struct rt_prio_array *array = &rt_rq->active;
+        struct rt_rq *group_rq = group_rt_rq(rt_se);
+
+        if (group_rq && group_rq->rt_throttled)
+                return;
+
+        list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+        __set_bit(rt_se_prio(rt_se), array->bitmap);
+
+        inc_rt_tasks(rt_se, rt_rq);
+}
+
+static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
 {
-        struct rt_prio_array *array = &rq->rt.active;
+        struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
+        struct rt_prio_array *array = &rt_rq->active;
+
+        list_del_init(&rt_se->run_list);
+        if (list_empty(array->queue + rt_se_prio(rt_se)))
+                __clear_bit(rt_se_prio(rt_se), array->bitmap);
 
-        list_add_tail(&p->run_list, array->queue + p->prio);
-        __set_bit(p->prio, array->bitmap);
+        dec_rt_tasks(rt_se, rt_rq);
+}
+
+/*
+ * Because the prio of an upper entry depends on the lower
+ * entries, we must remove entries top - down.
+ *
+ * XXX: O(1/2 h^2) because we can only walk up, not down the chain.
+ *      doesn't matter much for now, as h=2 for GROUP_SCHED.
+ */
+static void dequeue_rt_stack(struct task_struct *p)
+{
+        struct sched_rt_entity *rt_se, *top_se;
+
+        /*
+         * dequeue all, top - down.
+         */
+        do {
+                rt_se = &p->rt;
+                top_se = NULL;
+                for_each_sched_rt_entity(rt_se) {
+                        if (on_rt_rq(rt_se))
+                                top_se = rt_se;
+                }
+                if (top_se)
+                        dequeue_rt_entity(top_se);
+        } while (top_se);
 }
 
 /*
  * Adding/removing a task to/from a priority array:
  */
+static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
+{
+        struct sched_rt_entity *rt_se = &p->rt;
+
+        if (wakeup)
+                rt_se->timeout = 0;
+
+        dequeue_rt_stack(p);
+
+        /*
+         * enqueue everybody, bottom - up.
+         */
+        for_each_sched_rt_entity(rt_se)
+                enqueue_rt_entity(rt_se);
+
+        inc_cpu_load(rq, p->se.load.weight);
+}
+
 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
 {
-        struct rt_prio_array *array = &rq->rt.active;
+        struct sched_rt_entity *rt_se = &p->rt;
+        struct rt_rq *rt_rq;
 
         update_curr_rt(rq);
 
-        list_del(&p->run_list);
-        if (list_empty(array->queue + p->prio))
-                __clear_bit(p->prio, array->bitmap);
+        dequeue_rt_stack(p);
+
+        /*
+         * re-enqueue all non-empty rt_rq entities.
+         */
+        for_each_sched_rt_entity(rt_se) {
+                rt_rq = group_rt_rq(rt_se);
+                if (rt_rq && rt_rq->rt_nr_running)
+                        enqueue_rt_entity(rt_se);
+        }
+
+        dec_cpu_load(rq, p->se.load.weight);
 }
 
 /*
  * Put task to the end of the run list without the overhead of dequeue
  * followed by enqueue.
  */
+static
+void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
+{
+        struct rt_prio_array *array = &rt_rq->active;
+
+        list_move_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+}
+
 static void requeue_task_rt(struct rq *rq, struct task_struct *p)
 {
-        struct rt_prio_array *array = &rq->rt.active;
+        struct sched_rt_entity *rt_se = &p->rt;
+        struct rt_rq *rt_rq;
 
-        list_move_tail(&p->run_list, array->queue + p->prio);
+        for_each_sched_rt_entity(rt_se) {
+                rt_rq = rt_rq_of_se(rt_se);
+                requeue_rt_entity(rt_rq, rt_se);
+        }
 }
 
-static void
-yield_task_rt(struct rq *rq)
+static void yield_task_rt(struct rq *rq)
 {
         requeue_task_rt(rq, rq->curr);
 }
 
+#ifdef CONFIG_SMP
+static int find_lowest_rq(struct task_struct *task);
+
+static int select_task_rq_rt(struct task_struct *p, int sync)
+{
+        struct rq *rq = task_rq(p);
+
+        /*
+         * If the current task is an RT task, then
+         * try to see if we can wake this RT task up on another
+         * runqueue. Otherwise simply start this RT task
+         * on its current runqueue.
+         *
+         * We want to avoid overloading runqueues. Even if
+         * the RT task is of higher priority than the current RT task.
+         * RT tasks behave differently than other tasks. If
+         * one gets preempted, we try to push it off to another queue.
+         * So trying to keep a preempting RT task on the same
+         * cache hot CPU will force the running RT task to
+         * a cold CPU. So we waste all the cache for the lower
+         * RT task in hopes of saving some of a RT task
+         * that is just being woken and probably will have
+         * cold cache anyway.
+         */
+        if (unlikely(rt_task(rq->curr)) &&
+            (p->rt.nr_cpus_allowed > 1)) {
+                int cpu = find_lowest_rq(p);
+
+                return (cpu == -1) ? task_cpu(p) : cpu;
+        }
+
+        /*
+         * Otherwise, just let it ride on the affined RQ and the
+         * post-schedule router will push the preempted task away
+         */
+        return task_cpu(p);
+}
+#endif /* CONFIG_SMP */
+
 /*
  * Preempt the current task with a newly woken task if needed:
  */
@@ -74,25 +468,48 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
                 resched_task(rq->curr);
 }
 
-static struct task_struct *pick_next_task_rt(struct rq *rq)
+static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
+                                                   struct rt_rq *rt_rq)
 {
-        struct rt_prio_array *array = &rq->rt.active;
-        struct task_struct *next;
+        struct rt_prio_array *array = &rt_rq->active;
+        struct sched_rt_entity *next = NULL;
         struct list_head *queue;
         int idx;
 
         idx = sched_find_first_bit(array->bitmap);
-        if (idx >= MAX_RT_PRIO)
-                return NULL;
+        BUG_ON(idx >= MAX_RT_PRIO);
 
         queue = array->queue + idx;
-        next = list_entry(queue->next, struct task_struct, run_list);
-
-        next->se.exec_start = rq->clock;
+        next = list_entry(queue->next, struct sched_rt_entity, run_list);
 
         return next;
 }
 
+static struct task_struct *pick_next_task_rt(struct rq *rq)
+{
+        struct sched_rt_entity *rt_se;
+        struct task_struct *p;
+        struct rt_rq *rt_rq;
+
+        rt_rq = &rq->rt;
+
+        if (unlikely(!rt_rq->rt_nr_running))
+                return NULL;
+
+        if (sched_rt_ratio_exceeded(rt_rq))
+                return NULL;
+
+        do {
+                rt_se = pick_next_rt_entity(rq, rt_rq);
+                BUG_ON(!rt_se);
+                rt_rq = group_rt_rq(rt_se);
+        } while (rt_rq);
+
+        p = rt_task_of(rt_se);
+        p->se.exec_start = rq->clock;
+        return p;
+}
+
 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
 {
         update_curr_rt(rq);
@@ -100,76 +517,448 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
 }
 
 #ifdef CONFIG_SMP
-/*
- * Load-balancing iterator. Note: while the runqueue stays locked
- * during the whole iteration, the current task might be
- * dequeued so the iterator has to be dequeue-safe. Here we
- * achieve that by always pre-iterating before returning
- * the current task:
- */
-static struct task_struct *load_balance_start_rt(void *arg)
+
+/* Only try algorithms three times */
+#define RT_MAX_TRIES 3
+
+static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
+static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
+
+static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
 {
-        struct rq *rq = arg;
-        struct rt_prio_array *array = &rq->rt.active;
-        struct list_head *head, *curr;
-        struct task_struct *p;
+        if (!task_running(rq, p) &&
+            (cpu < 0 || cpu_isset(cpu, p->cpus_allowed)) &&
+            (p->rt.nr_cpus_allowed > 1))
+                return 1;
+        return 0;
+}
+
+/* Return the second highest RT task, NULL otherwise */
+static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
+{
+        struct task_struct *next = NULL;
+        struct sched_rt_entity *rt_se;
+        struct rt_prio_array *array;
+        struct rt_rq *rt_rq;
         int idx;
 
-        idx = sched_find_first_bit(array->bitmap);
-        if (idx >= MAX_RT_PRIO)
-                return NULL;
+        for_each_leaf_rt_rq(rt_rq, rq) {
+                array = &rt_rq->active;
+                idx = sched_find_first_bit(array->bitmap);
+ next_idx:
+                if (idx >= MAX_RT_PRIO)
+                        continue;
+                if (next && next->prio < idx)
+                        continue;
+                list_for_each_entry(rt_se, array->queue + idx, run_list) {
+                        struct task_struct *p = rt_task_of(rt_se);
+                        if (pick_rt_task(rq, p, cpu)) {
+                                next = p;
+                                break;
+                        }
+                }
+                if (!next) {
+                        idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
+                        goto next_idx;
+                }
+        }
 
-        head = array->queue + idx;
-        curr = head->prev;
+        return next;
+}
 
-        p = list_entry(curr, struct task_struct, run_list);
+static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
 
-        curr = curr->prev;
+static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
+{
+        int       lowest_prio = -1;
+        int       lowest_cpu  = -1;
+        int       count       = 0;
+        int       cpu;
 
-        rq->rt.rt_load_balance_idx = idx;
-        rq->rt.rt_load_balance_head = head;
-        rq->rt.rt_load_balance_curr = curr;
+        cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed);
 
-        return p;
+        /*
+         * Scan each rq for the lowest prio.
+         */
+        for_each_cpu_mask(cpu, *lowest_mask) {
+                struct rq *rq = cpu_rq(cpu);
+
+                /* We look for lowest RT prio or non-rt CPU */
+                if (rq->rt.highest_prio >= MAX_RT_PRIO) {
+                        /*
+                         * if we already found a low RT queue
+                         * and now we found this non-rt queue
+                         * clear the mask and set our bit.
+                         * Otherwise just return the queue as is
+                         * and the count==1 will cause the algorithm
+                         * to use the first bit found.
+                         */
+                        if (lowest_cpu != -1) {
+                                cpus_clear(*lowest_mask);
+                                cpu_set(rq->cpu, *lowest_mask);
+                        }
+                        return 1;
+                }
+
+                /* no locking for now */
+                if ((rq->rt.highest_prio > task->prio)
+                    && (rq->rt.highest_prio >= lowest_prio)) {
+                        if (rq->rt.highest_prio > lowest_prio) {
+                                /* new low - clear old data */
+                                lowest_prio = rq->rt.highest_prio;
+                                lowest_cpu = cpu;
+                                count = 0;
+                        }
+                        count++;
+                } else
+                        cpu_clear(cpu, *lowest_mask);
+        }
+
+        /*
+         * Clear out all the set bits that represent
+         * runqueues that were of higher prio than
+         * the lowest_prio.
+         */
+        if (lowest_cpu > 0) {
+                /*
+                 * Perhaps we could add another cpumask op to
+                 * zero out bits. Like cpu_zero_bits(cpumask, nrbits);
+                 * Then that could be optimized to use memset and such.
+                 */
+                for_each_cpu_mask(cpu, *lowest_mask) {
+                        if (cpu >= lowest_cpu)
+                                break;
+                        cpu_clear(cpu, *lowest_mask);
+                }
+        }
+
+        return count;
 }
 
-static struct task_struct *load_balance_next_rt(void *arg)
+static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
 {
-        struct rq *rq = arg;
-        struct rt_prio_array *array = &rq->rt.active;
-        struct list_head *head, *curr;
-        struct task_struct *p;
-        int idx;
+        int first;
+
+        /* "this_cpu" is cheaper to preempt than a remote processor */
+        if ((this_cpu != -1) && cpu_isset(this_cpu, *mask))
+                return this_cpu;
+
+        first = first_cpu(*mask);
+        if (first != NR_CPUS)
+                return first;
+
+        return -1;
+}
+
+static int find_lowest_rq(struct task_struct *task)
+{
+        struct sched_domain *sd;
+        cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
+        int this_cpu = smp_processor_id();
+        int cpu      = task_cpu(task);
+        int count    = find_lowest_cpus(task, lowest_mask);
 
-        idx = rq->rt.rt_load_balance_idx;
-        head = rq->rt.rt_load_balance_head;
-        curr = rq->rt.rt_load_balance_curr;
+        if (!count)
+                return -1; /* No targets found */
 
         /*
-         * If we arrived back to the head again then
-         * iterate to the next queue (if any):
+         * There is no sense in performing an optimal search if only one
+         * target is found.
          */
-        if (unlikely(head == curr)) {
-                int next_idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
+        if (count == 1)
+                return first_cpu(*lowest_mask);
 
-                if (next_idx >= MAX_RT_PRIO)
-                        return NULL;
+        /*
+         * At this point we have built a mask of cpus representing the
+         * lowest priority tasks in the system.  Now we want to elect
+         * the best one based on our affinity and topology.
+         *
+         * We prioritize the last cpu that the task executed on since
+         * it is most likely cache-hot in that location.
+         */
+        if (cpu_isset(cpu, *lowest_mask))
+                return cpu;
+
+        /*
+         * Otherwise, we consult the sched_domains span maps to figure
+         * out which cpu is logically closest to our hot cache data.
+         */
+        if (this_cpu == cpu)
+                this_cpu = -1; /* Skip this_cpu opt if the same */
+
+        for_each_domain(cpu, sd) {
+                if (sd->flags & SD_WAKE_AFFINE) {
+                        cpumask_t domain_mask;
+                        int       best_cpu;
 
-                idx = next_idx;
-                head = array->queue + idx;
-                curr = head->prev;
+                        cpus_and(domain_mask, sd->span, *lowest_mask);
 
-                rq->rt.rt_load_balance_idx = idx;
-                rq->rt.rt_load_balance_head = head;
+                        best_cpu = pick_optimal_cpu(this_cpu,
+                                                    &domain_mask);
+                        if (best_cpu != -1)
+                                return best_cpu;
+                }
         }
 
-        p = list_entry(curr, struct task_struct, run_list);
+        /*
+         * And finally, if there were no matches within the domains
+         * just give the caller *something* to work with from the compatible
+         * locations.
+         */
+        return pick_optimal_cpu(this_cpu, lowest_mask);
+}
 
-        curr = curr->prev;
+/* Will lock the rq it finds */
+static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
+{
+        struct rq *lowest_rq = NULL;
+        int tries;
+        int cpu;
 
-        rq->rt.rt_load_balance_curr = curr;
+        for (tries = 0; tries < RT_MAX_TRIES; tries++) {
+                cpu = find_lowest_rq(task);
 
-        return p;
+                if ((cpu == -1) || (cpu == rq->cpu))
+                        break;
+
+                lowest_rq = cpu_rq(cpu);
+
+                /* if the prio of this runqueue changed, try again */
+                if (double_lock_balance(rq, lowest_rq)) {
+                        /*
+                         * We had to unlock the run queue. In
+                         * the mean time, task could have
+                         * migrated already or had its affinity changed.
+                         * Also make sure that it wasn't scheduled on its rq.
+                         */
+                        if (unlikely(task_rq(task) != rq ||
+                                     !cpu_isset(lowest_rq->cpu,
+                                                task->cpus_allowed) ||
+                                     task_running(rq, task) ||
+                                     !task->se.on_rq)) {
+
+                                spin_unlock(&lowest_rq->lock);
+                                lowest_rq = NULL;
+                                break;
+                        }
+                }
+
+                /* If this rq is still suitable use it. */
+                if (lowest_rq->rt.highest_prio > task->prio)
+                        break;
+
+                /* try again */
+                spin_unlock(&lowest_rq->lock);
+                lowest_rq = NULL;
+        }
+
+        return lowest_rq;
+}
+
+/*
+ * If the current CPU has more than one RT task, see if the non
+ * running task can migrate over to a CPU that is running a task
+ * of lesser priority.
+ */
+static int push_rt_task(struct rq *rq)
+{
+        struct task_struct *next_task;
+        struct rq *lowest_rq;
+        int ret = 0;
+        int paranoid = RT_MAX_TRIES;
+
+        if (!rq->rt.overloaded)
+                return 0;
+
+        next_task = pick_next_highest_task_rt(rq, -1);
+        if (!next_task)
+                return 0;
+
+ retry:
+        if (unlikely(next_task == rq->curr)) {
+                WARN_ON(1);
+                return 0;
+        }
+
+        /*
+         * It's possible that the next_task slipped in of
+         * higher priority than current. If that's the case
+         * just reschedule current.
+         */
+        if (unlikely(next_task->prio < rq->curr->prio)) {
+                resched_task(rq->curr);
+                return 0;
+        }
+
+        /* We might release rq lock */
+        get_task_struct(next_task);
+
+        /* find_lock_lowest_rq locks the rq if found */
+        lowest_rq = find_lock_lowest_rq(next_task, rq);
+        if (!lowest_rq) {
+                struct task_struct *task;
+                /*
+                 * find lock_lowest_rq releases rq->lock
+                 * so it is possible that next_task has changed.
+                 * If it has, then try again.
+                 */
+                task = pick_next_highest_task_rt(rq, -1);
+                if (unlikely(task != next_task) && task && paranoid--) {
+                        put_task_struct(next_task);
+                        next_task = task;
+                        goto retry;
+                }
+                goto out;
+        }
+
+        deactivate_task(rq, next_task, 0);
+        set_task_cpu(next_task, lowest_rq->cpu);
+        activate_task(lowest_rq, next_task, 0);
+
+        resched_task(lowest_rq->curr);
+
+        spin_unlock(&lowest_rq->lock);
+
+        ret = 1;
+out:
+        put_task_struct(next_task);
+
+        return ret;
+}
+
+/*
+ * TODO: Currently we just use the second highest prio task on
+ *       the queue, and stop when it can't migrate (or there's
+ *       no more RT tasks).  There may be a case where a lower
+ *       priority RT task has a different affinity than the
+ *       higher RT task. In this case the lower RT task could
+ *       possibly be able to migrate where as the higher priority
+ *       RT task could not.  We currently ignore this issue.
+ *       Enhancements are welcome!
+ */
+static void push_rt_tasks(struct rq *rq)
+{
+        /* push_rt_task will return true if it moved an RT */
+        while (push_rt_task(rq))
+                ;
+}
+
+static int pull_rt_task(struct rq *this_rq)
+{
+        int this_cpu = this_rq->cpu, ret = 0, cpu;
+        struct task_struct *p, *next;
+        struct rq *src_rq;
+
+        if (likely(!rt_overloaded(this_rq)))
+                return 0;
+
+        next = pick_next_task_rt(this_rq);
+
+        for_each_cpu_mask(cpu, this_rq->rd->rto_mask) {
+                if (this_cpu == cpu)
+                        continue;
+
+                src_rq = cpu_rq(cpu);
+                /*
+                 * We can potentially drop this_rq's lock in
+                 * double_lock_balance, and another CPU could
+                 * steal our next task - hence we must cause
+                 * the caller to recalculate the next task
+                 * in that case:
+                 */
+                if (double_lock_balance(this_rq, src_rq)) {
+                        struct task_struct *old_next = next;
+
+                        next = pick_next_task_rt(this_rq);
+                        if (next != old_next)
+                                ret = 1;
+                }
+
+                /*
+                 * Are there still pullable RT tasks?
+                 */
+                if (src_rq->rt.rt_nr_running <= 1)
+                        goto skip;
+
+                p = pick_next_highest_task_rt(src_rq, this_cpu);
+
+                /*
+                 * Do we have an RT task that preempts
+                 * the to-be-scheduled task?
+                 */
+                if (p && (!next || (p->prio < next->prio))) {
+                        WARN_ON(p == src_rq->curr);
+                        WARN_ON(!p->se.on_rq);
+
+                        /*
+                         * There's a chance that p is higher in priority
+                         * than what's currently running on its cpu.
+                         * This is just that p is wakeing up and hasn't
+                         * had a chance to schedule. We only pull
+                         * p if it is lower in priority than the
+                         * current task on the run queue or
+                         * this_rq next task is lower in prio than
+                         * the current task on that rq.
+                         */
+                        if (p->prio < src_rq->curr->prio ||
+                            (next && next->prio < src_rq->curr->prio))
+                                goto skip;
+
+                        ret = 1;
+
+                        deactivate_task(src_rq, p, 0);
+                        set_task_cpu(p, this_cpu);
+                        activate_task(this_rq, p, 0);
+                        /*
+                         * We continue with the search, just in
+                         * case there's an even higher prio task
+                         * in another runqueue. (low likelyhood
+                         * but possible)
+                         *
+                         * Update next so that we won't pick a task
+                         * on another cpu with a priority lower (or equal)
+                         * than the one we just picked.
+                         */
+                        next = p;
+
+                }
+ skip:
+                spin_unlock(&src_rq->lock);
+        }
+
+        return ret;
+}
+
+static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
+{
+        /* Try to pull RT tasks here if we lower this rq's prio */
+        if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
+                pull_rt_task(rq);
+}
+
+static void post_schedule_rt(struct rq *rq)
+{
+        /*
+         * If we have more than one rt_task queued, then
+         * see if we can push the other rt_tasks off to other CPUS.
+         * Note we may release the rq lock, and since
+         * the lock was owned by prev, we need to release it
+         * first via finish_lock_switch and then reaquire it here.
+         */
+        if (unlikely(rq->rt.overloaded)) {
+                spin_lock_irq(&rq->lock);
+                push_rt_tasks(rq);
+                spin_unlock_irq(&rq->lock);
+        }
+}
+
+
+static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
+{
+        if (!task_running(rq, p) &&
+            (p->prio >= rq->rt.highest_prio) &&
+            rq->rt.overloaded)
+                push_rt_tasks(rq);
 }
 
 static unsigned long
@@ -178,38 +967,170 @@ load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
                 struct sched_domain *sd, enum cpu_idle_type idle,
                 int *all_pinned, int *this_best_prio)
 {
-        struct rq_iterator rt_rq_iterator;
-
-        rt_rq_iterator.start = load_balance_start_rt;
-        rt_rq_iterator.next = load_balance_next_rt;
-        /* pass 'busiest' rq argument into
-         * load_balance_[start|next]_rt iterators
-         */
-        rt_rq_iterator.arg = busiest;
-
-        return balance_tasks(this_rq, this_cpu, busiest, max_load_move, sd,
-                             idle, all_pinned, this_best_prio, &rt_rq_iterator);
+        /* don't touch RT tasks */
+        return 0;
 }
 
 static int
 move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
                  struct sched_domain *sd, enum cpu_idle_type idle)
 {
-        struct rq_iterator rt_rq_iterator;
+        /* don't touch RT tasks */
+        return 0;
+}
+
+static void set_cpus_allowed_rt(struct task_struct *p, cpumask_t *new_mask)
+{
+        int weight = cpus_weight(*new_mask);
+
+        BUG_ON(!rt_task(p));
 
-        rt_rq_iterator.start = load_balance_start_rt;
-        rt_rq_iterator.next = load_balance_next_rt;
-        rt_rq_iterator.arg = busiest;
+        /*
+         * Update the migration status of the RQ if we have an RT task
+         * which is running AND changing its weight value.
+         */
+        if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
+                struct rq *rq = task_rq(p);
+
+                if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
+                        rq->rt.rt_nr_migratory++;
+                } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
+                        BUG_ON(!rq->rt.rt_nr_migratory);
+                        rq->rt.rt_nr_migratory--;
+                }
+
+                update_rt_migration(rq);
+        }
 
-        return iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
-                                  &rt_rq_iterator);
+        p->cpus_allowed    = *new_mask;
+        p->rt.nr_cpus_allowed = weight;
 }
-#endif
 
-static void task_tick_rt(struct rq *rq, struct task_struct *p)
+/* Assumes rq->lock is held */
+static void join_domain_rt(struct rq *rq)
+{
+        if (rq->rt.overloaded)
+                rt_set_overload(rq);
+}
+
+/* Assumes rq->lock is held */
+static void leave_domain_rt(struct rq *rq)
+{
+        if (rq->rt.overloaded)
+                rt_clear_overload(rq);
+}
+
+/*
+ * When switch from the rt queue, we bring ourselves to a position
+ * that we might want to pull RT tasks from other runqueues.
+ */
+static void switched_from_rt(struct rq *rq, struct task_struct *p,
+                           int running)
+{
+        /*
+         * If there are other RT tasks then we will reschedule
+         * and the scheduling of the other RT tasks will handle
+         * the balancing. But if we are the last RT task
+         * we may need to handle the pulling of RT tasks
+         * now.
+         */
+        if (!rq->rt.rt_nr_running)
+                pull_rt_task(rq);
+}
+#endif /* CONFIG_SMP */
+
+/*
+ * When switching a task to RT, we may overload the runqueue
+ * with RT tasks. In this case we try to push them off to
+ * other runqueues.
+ */
+static void switched_to_rt(struct rq *rq, struct task_struct *p,
+                           int running)
+{
+        int check_resched = 1;
+
+        /*
+         * If we are already running, then there's nothing
+         * that needs to be done. But if we are not running
+         * we may need to preempt the current running task.
+         * If that current running task is also an RT task
+         * then see if we can move to another run queue.
+         */
+        if (!running) {
+#ifdef CONFIG_SMP
+                if (rq->rt.overloaded && push_rt_task(rq) &&
+                    /* Don't resched if we changed runqueues */
+                    rq != task_rq(p))
+                        check_resched = 0;
+#endif /* CONFIG_SMP */
+                if (check_resched && p->prio < rq->curr->prio)
+                        resched_task(rq->curr);
+        }
+}
+
+/*
+ * Priority of the task has changed. This may cause
+ * us to initiate a push or pull.
+ */
+static void prio_changed_rt(struct rq *rq, struct task_struct *p,
+                            int oldprio, int running)
+{
+        if (running) {
+#ifdef CONFIG_SMP
+                /*
+                 * If our priority decreases while running, we
+                 * may need to pull tasks to this runqueue.
+                 */
+                if (oldprio < p->prio)
+                        pull_rt_task(rq);
+                /*
+                 * If there's a higher priority task waiting to run
+                 * then reschedule.
+                 */
+                if (p->prio > rq->rt.highest_prio)
+                        resched_task(p);
+#else
+                /* For UP simply resched on drop of prio */
+                if (oldprio < p->prio)
+                        resched_task(p);
+#endif /* CONFIG_SMP */
+        } else {
+                /*
+                 * This task is not running, but if it is
+                 * greater than the current running task
+                 * then reschedule.
+                 */
+                if (p->prio < rq->curr->prio)
+                        resched_task(rq->curr);
+        }
+}
+
+static void watchdog(struct rq *rq, struct task_struct *p)
+{
+        unsigned long soft, hard;
+
+        if (!p->signal)
+                return;
+
+        soft = p->signal->rlim[RLIMIT_RTTIME].rlim_cur;
+        hard = p->signal->rlim[RLIMIT_RTTIME].rlim_max;
+
+        if (soft != RLIM_INFINITY) {
+                unsigned long next;
+
+                p->rt.timeout++;
+                next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
+                if (p->rt.timeout > next)
+                        p->it_sched_expires = p->se.sum_exec_runtime;
+        }
+}
+
+static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
 {
         update_curr_rt(rq);
 
+        watchdog(rq, p);
+
         /*
          * RR tasks need a special form of timeslice management.
          * FIFO tasks have no timeslices.
@@ -217,16 +1138,16 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p)
         if (p->policy != SCHED_RR)
                 return;
 
-        if (--p->time_slice)
+        if (--p->rt.time_slice)
                 return;
 
-        p->time_slice = DEF_TIMESLICE;
+        p->rt.time_slice = DEF_TIMESLICE;
 
         /*
          * Requeue to the end of queue if we are not the only element
          * on the queue:
          */
-        if (p->run_list.prev != p->run_list.next) {
+        if (p->rt.run_list.prev != p->rt.run_list.next) {
                 requeue_task_rt(rq, p);
                 set_tsk_need_resched(p);
         }
@@ -244,6 +1165,9 @@ const struct sched_class rt_sched_class = {
         .enqueue_task           = enqueue_task_rt,
         .dequeue_task           = dequeue_task_rt,
         .yield_task             = yield_task_rt,
+#ifdef CONFIG_SMP
+        .select_task_rq         = select_task_rq_rt,
+#endif /* CONFIG_SMP */
 
         .check_preempt_curr     = check_preempt_curr_rt,
 
@@ -253,8 +1177,18 @@ const struct sched_class rt_sched_class = {
 #ifdef CONFIG_SMP
         .load_balance           = load_balance_rt,
         .move_one_task          = move_one_task_rt,
+        .set_cpus_allowed       = set_cpus_allowed_rt,
+        .join_domain            = join_domain_rt,
+        .leave_domain           = leave_domain_rt,
+        .pre_schedule           = pre_schedule_rt,
+        .post_schedule          = post_schedule_rt,
+        .task_wake_up           = task_wake_up_rt,
+        .switched_from          = switched_from_rt,
 #endif
 
         .set_curr_task          = set_curr_task_rt,
         .task_tick              = task_tick_rt,
+
+        .prio_changed           = prio_changed_rt,
+        .switched_to            = switched_to_rt,
 };