1 files changed, 1639 insertions, 0 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
new file mode 100644
index 000000000000..6e79b3faa4cd
--- /dev/null
+++ b/kernel/sched/deadline.c
@@ -0,0 +1,1639 @@
+/*
+ * Deadline Scheduling Class (SCHED_DEADLINE)
+ *
+ * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
+ *
+ * Tasks that periodically executes their instances for less than their
+ * runtime won't miss any of their deadlines.
+ * Tasks that are not periodic or sporadic or that tries to execute more
+ * than their reserved bandwidth will be slowed down (and may potentially
+ * miss some of their deadlines), and won't affect any other task.
+ *
+ * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
+ *                    Juri Lelli <juri.lelli@gmail.com>,
+ *                    Michael Trimarchi <michael@amarulasolutions.com>,
+ *                    Fabio Checconi <fchecconi@gmail.com>
+ */
+#include "sched.h"
+
+#include <linux/slab.h>
+
+struct dl_bandwidth def_dl_bandwidth;
+
+static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
+{
+        return container_of(dl_se, struct task_struct, dl);
+}
+
+static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
+{
+        return container_of(dl_rq, struct rq, dl);
+}
+
+static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
+{
+        struct task_struct *p = dl_task_of(dl_se);
+        struct rq *rq = task_rq(p);
+
+        return &rq->dl;
+}
+
+static inline int on_dl_rq(struct sched_dl_entity *dl_se)
+{
+        return !RB_EMPTY_NODE(&dl_se->rb_node);
+}
+
+static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
+{
+        struct sched_dl_entity *dl_se = &p->dl;
+
+        return dl_rq->rb_leftmost == &dl_se->rb_node;
+}
+
+void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
+{
+        raw_spin_lock_init(&dl_b->dl_runtime_lock);
+        dl_b->dl_period = period;
+        dl_b->dl_runtime = runtime;
+}
+
+extern unsigned long to_ratio(u64 period, u64 runtime);
+
+void init_dl_bw(struct dl_bw *dl_b)
+{
+        raw_spin_lock_init(&dl_b->lock);
+        raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock);
+        if (global_rt_runtime() == RUNTIME_INF)
+                dl_b->bw = -1;
+        else
+                dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
+        raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock);
+        dl_b->total_bw = 0;
+}
+
+void init_dl_rq(struct dl_rq *dl_rq, struct rq *rq)
+{
+        dl_rq->rb_root = RB_ROOT;
+
+#ifdef CONFIG_SMP
+        /* zero means no -deadline tasks */
+        dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
+
+        dl_rq->dl_nr_migratory = 0;
+        dl_rq->overloaded = 0;
+        dl_rq->pushable_dl_tasks_root = RB_ROOT;
+#else
+        init_dl_bw(&dl_rq->dl_bw);
+#endif
+}
+
+#ifdef CONFIG_SMP
+
+static inline int dl_overloaded(struct rq *rq)
+{
+        return atomic_read(&rq->rd->dlo_count);
+}
+
+static inline void dl_set_overload(struct rq *rq)
+{
+        if (!rq->online)
+                return;
+
+        cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
+        /*
+         * Must be visible before the overload count is
+         * set (as in sched_rt.c).
+         *
+         * Matched by the barrier in pull_dl_task().
+         */
+        smp_wmb();
+        atomic_inc(&rq->rd->dlo_count);
+}
+
+static inline void dl_clear_overload(struct rq *rq)
+{
+        if (!rq->online)
+                return;
+
+        atomic_dec(&rq->rd->dlo_count);
+        cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
+}
+
+static void update_dl_migration(struct dl_rq *dl_rq)
+{
+        if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) {
+                if (!dl_rq->overloaded) {
+                        dl_set_overload(rq_of_dl_rq(dl_rq));
+                        dl_rq->overloaded = 1;
+                }
+        } else if (dl_rq->overloaded) {
+                dl_clear_overload(rq_of_dl_rq(dl_rq));
+                dl_rq->overloaded = 0;
+        }
+}
+
+static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+        struct task_struct *p = dl_task_of(dl_se);
+
+        if (p->nr_cpus_allowed > 1)
+                dl_rq->dl_nr_migratory++;
+
+        update_dl_migration(dl_rq);
+}
+
+static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+        struct task_struct *p = dl_task_of(dl_se);
+
+        if (p->nr_cpus_allowed > 1)
+                dl_rq->dl_nr_migratory--;
+
+        update_dl_migration(dl_rq);
+}
+
+/*
+ * The list of pushable -deadline task is not a plist, like in
+ * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
+ */
+static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
+{
+        struct dl_rq *dl_rq = &rq->dl;
+        struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_node;
+        struct rb_node *parent = NULL;
+        struct task_struct *entry;
+        int leftmost = 1;
+
+        BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
+
+        while (*link) {
+                parent = *link;
+                entry = rb_entry(parent, struct task_struct,
+                                 pushable_dl_tasks);
+                if (dl_entity_preempt(&p->dl, &entry->dl))
+                        link = &parent->rb_left;
+                else {
+                        link = &parent->rb_right;
+                        leftmost = 0;
+                }
+        }
+
+        if (leftmost)
+                dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks;
+
+        rb_link_node(&p->pushable_dl_tasks, parent, link);
+        rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
+}
+
+static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
+{
+        struct dl_rq *dl_rq = &rq->dl;
+
+        if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
+                return;
+
+        if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) {
+                struct rb_node *next_node;
+
+                next_node = rb_next(&p->pushable_dl_tasks);
+                dl_rq->pushable_dl_tasks_leftmost = next_node;
+        }
+
+        rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
+        RB_CLEAR_NODE(&p->pushable_dl_tasks);
+}
+
+static inline int has_pushable_dl_tasks(struct rq *rq)
+{
+        return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root);
+}
+
+static int push_dl_task(struct rq *rq);
+
+#else
+
+static inline
+void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
+{
+}
+
+static inline
+void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
+{
+}
+
+static inline
+void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+}
+
+static inline
+void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+}
+
+#endif /* CONFIG_SMP */
+
+static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
+static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
+static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
+                                  int flags);
+
+/*
+ * We are being explicitly informed that a new instance is starting,
+ * and this means that:
+ *  - the absolute deadline of the entity has to be placed at
+ *    current time + relative deadline;
+ *  - the runtime of the entity has to be set to the maximum value.
+ *
+ * The capability of specifying such event is useful whenever a -deadline
+ * entity wants to (try to!) synchronize its behaviour with the scheduler's
+ * one, and to (try to!) reconcile itself with its own scheduling
+ * parameters.
+ */
+static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se,
+                                       struct sched_dl_entity *pi_se)
+{
+        struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+        struct rq *rq = rq_of_dl_rq(dl_rq);
+
+        WARN_ON(!dl_se->dl_new || dl_se->dl_throttled);
+
+        /*
+         * We use the regular wall clock time to set deadlines in the
+         * future; in fact, we must consider execution overheads (time
+         * spent on hardirq context, etc.).
+         */
+        dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
+        dl_se->runtime = pi_se->dl_runtime;
+        dl_se->dl_new = 0;
+}
+
+/*
+ * Pure Earliest Deadline First (EDF) scheduling does not deal with the
+ * possibility of a entity lasting more than what it declared, and thus
+ * exhausting its runtime.
+ *
+ * Here we are interested in making runtime overrun possible, but we do
+ * not want a entity which is misbehaving to affect the scheduling of all
+ * other entities.
+ * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
+ * is used, in order to confine each entity within its own bandwidth.
+ *
+ * This function deals exactly with that, and ensures that when the runtime
+ * of a entity is replenished, its deadline is also postponed. That ensures
+ * the overrunning entity can't interfere with other entity in the system and
+ * can't make them miss their deadlines. Reasons why this kind of overruns
+ * could happen are, typically, a entity voluntarily trying to overcome its
+ * runtime, or it just underestimated it during sched_setscheduler_ex().
+ */
+static void replenish_dl_entity(struct sched_dl_entity *dl_se,
+                                struct sched_dl_entity *pi_se)
+{
+        struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+        struct rq *rq = rq_of_dl_rq(dl_rq);
+
+        BUG_ON(pi_se->dl_runtime <= 0);
+
+        /*
+         * This could be the case for a !-dl task that is boosted.
+         * Just go with full inherited parameters.
+         */
+        if (dl_se->dl_deadline == 0) {
+                dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
+                dl_se->runtime = pi_se->dl_runtime;
+        }
+
+        /*
+         * We keep moving the deadline away until we get some
+         * available runtime for the entity. This ensures correct
+         * handling of situations where the runtime overrun is
+         * arbitrary large.
+         */
+        while (dl_se->runtime <= 0) {
+                dl_se->deadline += pi_se->dl_period;
+                dl_se->runtime += pi_se->dl_runtime;
+        }
+
+        /*
+         * At this point, the deadline really should be "in
+         * the future" with respect to rq->clock. If it's
+         * not, we are, for some reason, lagging too much!
+         * Anyway, after having warn userspace abut that,
+         * we still try to keep the things running by
+         * resetting the deadline and the budget of the
+         * entity.
+         */
+        if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
+                static bool lag_once = false;
+
+                if (!lag_once) {
+                        lag_once = true;
+                        printk_sched("sched: DL replenish lagged to much\n");
+                }
+                dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
+                dl_se->runtime = pi_se->dl_runtime;
+        }
+}
+
+/*
+ * Here we check if --at time t-- an entity (which is probably being
+ * [re]activated or, in general, enqueued) can use its remaining runtime
+ * and its current deadline _without_ exceeding the bandwidth it is
+ * assigned (function returns true if it can't). We are in fact applying
+ * one of the CBS rules: when a task wakes up, if the residual runtime
+ * over residual deadline fits within the allocated bandwidth, then we
+ * can keep the current (absolute) deadline and residual budget without
+ * disrupting the schedulability of the system. Otherwise, we should
+ * refill the runtime and set the deadline a period in the future,
+ * because keeping the current (absolute) deadline of the task would
+ * result in breaking guarantees promised to other tasks (refer to
+ * Documentation/scheduler/sched-deadline.txt for more informations).
+ *
+ * This function returns true if:
+ *
+ *   runtime / (deadline - t) > dl_runtime / dl_period ,
+ *
+ * IOW we can't recycle current parameters.
+ *
+ * Notice that the bandwidth check is done against the period. For
+ * task with deadline equal to period this is the same of using
+ * dl_deadline instead of dl_period in the equation above.
+ */
+static bool dl_entity_overflow(struct sched_dl_entity *dl_se,
+                               struct sched_dl_entity *pi_se, u64 t)
+{
+        u64 left, right;
+
+        /*
+         * left and right are the two sides of the equation above,
+         * after a bit of shuffling to use multiplications instead
+         * of divisions.
+         *
+         * Note that none of the time values involved in the two
+         * multiplications are absolute: dl_deadline and dl_runtime
+         * are the relative deadline and the maximum runtime of each
+         * instance, runtime is the runtime left for the last instance
+         * and (deadline - t), since t is rq->clock, is the time left
+         * to the (absolute) deadline. Even if overflowing the u64 type
+         * is very unlikely to occur in both cases, here we scale down
+         * as we want to avoid that risk at all. Scaling down by 10
+         * means that we reduce granularity to 1us. We are fine with it,
+         * since this is only a true/false check and, anyway, thinking
+         * of anything below microseconds resolution is actually fiction
+         * (but still we want to give the user that illusion >;).
+         */
+        left = (pi_se->dl_period >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
+        right = ((dl_se->deadline - t) >> DL_SCALE) *
+                (pi_se->dl_runtime >> DL_SCALE);
+
+        return dl_time_before(right, left);
+}
+
+/*
+ * When a -deadline entity is queued back on the runqueue, its runtime and
+ * deadline might need updating.
+ *
+ * The policy here is that we update the deadline of the entity only if:
+ *  - the current deadline is in the past,
+ *  - using the remaining runtime with the current deadline would make
+ *    the entity exceed its bandwidth.
+ */
+static void update_dl_entity(struct sched_dl_entity *dl_se,
+                             struct sched_dl_entity *pi_se)
+{
+        struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+        struct rq *rq = rq_of_dl_rq(dl_rq);
+
+        /*
+         * The arrival of a new instance needs special treatment, i.e.,
+         * the actual scheduling parameters have to be "renewed".
+         */
+        if (dl_se->dl_new) {
+                setup_new_dl_entity(dl_se, pi_se);
+                return;
+        }
+
+        if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
+            dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) {
+                dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
+                dl_se->runtime = pi_se->dl_runtime;
+        }
+}
+
+/*
+ * If the entity depleted all its runtime, and if we want it to sleep
+ * while waiting for some new execution time to become available, we
+ * set the bandwidth enforcement timer to the replenishment instant
+ * and try to activate it.
+ *
+ * Notice that it is important for the caller to know if the timer
+ * actually started or not (i.e., the replenishment instant is in
+ * the future or in the past).
+ */
+static int start_dl_timer(struct sched_dl_entity *dl_se, bool boosted)
+{
+        struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+        struct rq *rq = rq_of_dl_rq(dl_rq);
+        ktime_t now, act;
+        ktime_t soft, hard;
+        unsigned long range;
+        s64 delta;
+
+        if (boosted)
+                return 0;
+        /*
+         * We want the timer to fire at the deadline, but considering
+         * that it is actually coming from rq->clock and not from
+         * hrtimer's time base reading.
+         */
+        act = ns_to_ktime(dl_se->deadline);
+        now = hrtimer_cb_get_time(&dl_se->dl_timer);
+        delta = ktime_to_ns(now) - rq_clock(rq);
+        act = ktime_add_ns(act, delta);
+
+        /*
+         * If the expiry time already passed, e.g., because the value
+         * chosen as the deadline is too small, don't even try to
+         * start the timer in the past!
+         */
+        if (ktime_us_delta(act, now) < 0)
+                return 0;
+
+        hrtimer_set_expires(&dl_se->dl_timer, act);
+
+        soft = hrtimer_get_softexpires(&dl_se->dl_timer);
+        hard = hrtimer_get_expires(&dl_se->dl_timer);
+        range = ktime_to_ns(ktime_sub(hard, soft));
+        __hrtimer_start_range_ns(&dl_se->dl_timer, soft,
+                                 range, HRTIMER_MODE_ABS, 0);
+
+        return hrtimer_active(&dl_se->dl_timer);
+}
+
+/*
+ * This is the bandwidth enforcement timer callback. If here, we know
+ * a task is not on its dl_rq, since the fact that the timer was running
+ * means the task is throttled and needs a runtime replenishment.
+ *
+ * However, what we actually do depends on the fact the task is active,
+ * (it is on its rq) or has been removed from there by a call to
+ * dequeue_task_dl(). In the former case we must issue the runtime
+ * replenishment and add the task back to the dl_rq; in the latter, we just
+ * do nothing but clearing dl_throttled, so that runtime and deadline
+ * updating (and the queueing back to dl_rq) will be done by the
+ * next call to enqueue_task_dl().
+ */
+static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
+{
+        struct sched_dl_entity *dl_se = container_of(timer,
+                                                     struct sched_dl_entity,
+                                                     dl_timer);
+        struct task_struct *p = dl_task_of(dl_se);
+        struct rq *rq = task_rq(p);
+        raw_spin_lock(&rq->lock);
+
+        /*
+         * We need to take care of a possible races here. In fact, the
+         * task might have changed its scheduling policy to something
+         * different from SCHED_DEADLINE or changed its reservation
+         * parameters (through sched_setscheduler()).
+         */
+        if (!dl_task(p) || dl_se->dl_new)
+                goto unlock;
+
+        sched_clock_tick();
+        update_rq_clock(rq);
+        dl_se->dl_throttled = 0;
+        if (p->on_rq) {
+                enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
+                if (task_has_dl_policy(rq->curr))
+                        check_preempt_curr_dl(rq, p, 0);
+                else
+                        resched_task(rq->curr);
+#ifdef CONFIG_SMP
+                /*
+                 * Queueing this task back might have overloaded rq,
+                 * check if we need to kick someone away.
+                 */
+                if (has_pushable_dl_tasks(rq))
+                        push_dl_task(rq);
+#endif
+        }
+unlock:
+        raw_spin_unlock(&rq->lock);
+
+        return HRTIMER_NORESTART;
+}
+
+void init_dl_task_timer(struct sched_dl_entity *dl_se)
+{
+        struct hrtimer *timer = &dl_se->dl_timer;
+
+        if (hrtimer_active(timer)) {
+                hrtimer_try_to_cancel(timer);
+                return;
+        }
+
+        hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+        timer->function = dl_task_timer;
+}
+
+static
+int dl_runtime_exceeded(struct rq *rq, struct sched_dl_entity *dl_se)
+{
+        int dmiss = dl_time_before(dl_se->deadline, rq_clock(rq));
+        int rorun = dl_se->runtime <= 0;
+
+        if (!rorun && !dmiss)
+                return 0;
+
+        /*
+         * If we are beyond our current deadline and we are still
+         * executing, then we have already used some of the runtime of
+         * the next instance. Thus, if we do not account that, we are
+         * stealing bandwidth from the system at each deadline miss!
+         */
+        if (dmiss) {
+                dl_se->runtime = rorun ? dl_se->runtime : 0;
+                dl_se->runtime -= rq_clock(rq) - dl_se->deadline;
+        }
+
+        return 1;
+}
+
+extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
+
+/*
+ * Update the current task's runtime statistics (provided it is still
+ * a -deadline task and has not been removed from the dl_rq).
+ */
+static void update_curr_dl(struct rq *rq)
+{
+        struct task_struct *curr = rq->curr;
+        struct sched_dl_entity *dl_se = &curr->dl;
+        u64 delta_exec;
+
+        if (!dl_task(curr) || !on_dl_rq(dl_se))
+                return;
+
+        /*
+         * Consumed budget is computed considering the time as
+         * observed by schedulable tasks (excluding time spent
+         * in hardirq context, etc.). Deadlines are instead
+         * computed using hard walltime. This seems to be the more
+         * natural solution, but the full ramifications of this
+         * approach need further study.
+         */
+        delta_exec = rq_clock_task(rq) - curr->se.exec_start;
+        if (unlikely((s64)delta_exec < 0))
+                delta_exec = 0;
+
+        schedstat_set(curr->se.statistics.exec_max,
+                      max(curr->se.statistics.exec_max, delta_exec));
+
+        curr->se.sum_exec_runtime += delta_exec;
+        account_group_exec_runtime(curr, delta_exec);
+
+        curr->se.exec_start = rq_clock_task(rq);
+        cpuacct_charge(curr, delta_exec);
+
+        sched_rt_avg_update(rq, delta_exec);
+
+        dl_se->runtime -= delta_exec;
+        if (dl_runtime_exceeded(rq, dl_se)) {
+                __dequeue_task_dl(rq, curr, 0);
+                if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted)))
+                        dl_se->dl_throttled = 1;
+                else
+                        enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
+
+                if (!is_leftmost(curr, &rq->dl))
+                        resched_task(curr);
+        }
+
+        /*
+         * Because -- for now -- we share the rt bandwidth, we need to
+         * account our runtime there too, otherwise actual rt tasks
+         * would be able to exceed the shared quota.
+         *
+         * Account to the root rt group for now.
+         *
+         * The solution we're working towards is having the RT groups scheduled
+         * using deadline servers -- however there's a few nasties to figure
+         * out before that can happen.
+         */
+        if (rt_bandwidth_enabled()) {
+                struct rt_rq *rt_rq = &rq->rt;
+
+                raw_spin_lock(&rt_rq->rt_runtime_lock);
+                /*
+                 * We'll let actual RT tasks worry about the overflow here, we
+                 * have our own CBS to keep us inline; only account when RT
+                 * bandwidth is relevant.
+                 */
+                if (sched_rt_bandwidth_account(rt_rq))
+                        rt_rq->rt_time += delta_exec;
+                raw_spin_unlock(&rt_rq->rt_runtime_lock);
+        }
+}
+
+#ifdef CONFIG_SMP
+
+static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu);
+
+static inline u64 next_deadline(struct rq *rq)
+{
+        struct task_struct *next = pick_next_earliest_dl_task(rq, rq->cpu);
+
+        if (next && dl_prio(next->prio))
+                return next->dl.deadline;
+        else
+                return 0;
+}
+
+static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
+{
+        struct rq *rq = rq_of_dl_rq(dl_rq);
+
+        if (dl_rq->earliest_dl.curr == 0 ||
+            dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
+                /*
+                 * If the dl_rq had no -deadline tasks, or if the new task
+                 * has shorter deadline than the current one on dl_rq, we
+                 * know that the previous earliest becomes our next earliest,
+                 * as the new task becomes the earliest itself.
+                 */
+                dl_rq->earliest_dl.next = dl_rq->earliest_dl.curr;
+                dl_rq->earliest_dl.curr = deadline;
+                cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
+        } else if (dl_rq->earliest_dl.next == 0 ||
+                   dl_time_before(deadline, dl_rq->earliest_dl.next)) {
+                /*
+                 * On the other hand, if the new -deadline task has a
+                 * a later deadline than the earliest one on dl_rq, but
+                 * it is earlier than the next (if any), we must
+                 * recompute the next-earliest.
+                 */
+                dl_rq->earliest_dl.next = next_deadline(rq);
+        }
+}
+
+static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
+{
+        struct rq *rq = rq_of_dl_rq(dl_rq);
+
+        /*
+         * Since we may have removed our earliest (and/or next earliest)
+         * task we must recompute them.
+         */
+        if (!dl_rq->dl_nr_running) {
+                dl_rq->earliest_dl.curr = 0;
+                dl_rq->earliest_dl.next = 0;
+                cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
+        } else {
+                struct rb_node *leftmost = dl_rq->rb_leftmost;
+                struct sched_dl_entity *entry;
+
+                entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
+                dl_rq->earliest_dl.curr = entry->deadline;
+                dl_rq->earliest_dl.next = next_deadline(rq);
+                cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
+        }
+}
+
+#else
+
+static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
+static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
+
+#endif /* CONFIG_SMP */
+
+static inline
+void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+        int prio = dl_task_of(dl_se)->prio;
+        u64 deadline = dl_se->deadline;
+
+        WARN_ON(!dl_prio(prio));
+        dl_rq->dl_nr_running++;
+        inc_nr_running(rq_of_dl_rq(dl_rq));
+
+        inc_dl_deadline(dl_rq, deadline);
+        inc_dl_migration(dl_se, dl_rq);
+}
+
+static inline
+void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
+{
+        int prio = dl_task_of(dl_se)->prio;
+
+        WARN_ON(!dl_prio(prio));
+        WARN_ON(!dl_rq->dl_nr_running);
+        dl_rq->dl_nr_running--;
+        dec_nr_running(rq_of_dl_rq(dl_rq));
+
+        dec_dl_deadline(dl_rq, dl_se->deadline);
+        dec_dl_migration(dl_se, dl_rq);
+}
+
+static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
+{
+        struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+        struct rb_node **link = &dl_rq->rb_root.rb_node;
+        struct rb_node *parent = NULL;
+        struct sched_dl_entity *entry;
+        int leftmost = 1;
+
+        BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
+
+        while (*link) {
+                parent = *link;
+                entry = rb_entry(parent, struct sched_dl_entity, rb_node);
+                if (dl_time_before(dl_se->deadline, entry->deadline))
+                        link = &parent->rb_left;
+                else {
+                        link = &parent->rb_right;
+                        leftmost = 0;
+                }
+        }
+
+        if (leftmost)
+                dl_rq->rb_leftmost = &dl_se->rb_node;
+
+        rb_link_node(&dl_se->rb_node, parent, link);
+        rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
+
+        inc_dl_tasks(dl_se, dl_rq);
+}
+
+static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
+{
+        struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+
+        if (RB_EMPTY_NODE(&dl_se->rb_node))
+                return;
+
+        if (dl_rq->rb_leftmost == &dl_se->rb_node) {
+                struct rb_node *next_node;
+
+                next_node = rb_next(&dl_se->rb_node);
+                dl_rq->rb_leftmost = next_node;
+        }
+
+        rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
+        RB_CLEAR_NODE(&dl_se->rb_node);
+
+        dec_dl_tasks(dl_se, dl_rq);
+}
+
+static void
+enqueue_dl_entity(struct sched_dl_entity *dl_se,
+                  struct sched_dl_entity *pi_se, int flags)
+{
+        BUG_ON(on_dl_rq(dl_se));
+
+        /*
+         * If this is a wakeup or a new instance, the scheduling
+         * parameters of the task might need updating. Otherwise,
+         * we want a replenishment of its runtime.
+         */
+        if (!dl_se->dl_new && flags & ENQUEUE_REPLENISH)
+                replenish_dl_entity(dl_se, pi_se);
+        else
+                update_dl_entity(dl_se, pi_se);
+
+        __enqueue_dl_entity(dl_se);
+}
+
+static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
+{
+        __dequeue_dl_entity(dl_se);
+}
+
+static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
+{
+        struct task_struct *pi_task = rt_mutex_get_top_task(p);
+        struct sched_dl_entity *pi_se = &p->dl;
+
+        /*
+         * Use the scheduling parameters of the top pi-waiter
+         * task if we have one and its (relative) deadline is
+         * smaller than our one... OTW we keep our runtime and
+         * deadline.
+         */
+        if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio))
+                pi_se = &pi_task->dl;
+
+        /*
+         * If p is throttled, we do nothing. In fact, if it exhausted
+         * its budget it needs a replenishment and, since it now is on
+         * its rq, the bandwidth timer callback (which clearly has not
+         * run yet) will take care of this.
+         */
+        if (p->dl.dl_throttled)
+                return;
+
+        enqueue_dl_entity(&p->dl, pi_se, flags);
+
+        if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
+                enqueue_pushable_dl_task(rq, p);
+}
+
+static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
+{
+        dequeue_dl_entity(&p->dl);
+        dequeue_pushable_dl_task(rq, p);
+}
+
+static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
+{
+        update_curr_dl(rq);
+        __dequeue_task_dl(rq, p, flags);
+}
+
+/*
+ * Yield task semantic for -deadline tasks is:
+ *
+ *   get off from the CPU until our next instance, with
+ *   a new runtime. This is of little use now, since we
+ *   don't have a bandwidth reclaiming mechanism. Anyway,
+ *   bandwidth reclaiming is planned for the future, and
+ *   yield_task_dl will indicate that some spare budget
+ *   is available for other task instances to use it.
+ */
+static void yield_task_dl(struct rq *rq)
+{
+        struct task_struct *p = rq->curr;
+
+        /*
+         * We make the task go to sleep until its current deadline by
+         * forcing its runtime to zero. This way, update_curr_dl() stops
+         * it and the bandwidth timer will wake it up and will give it
+         * new scheduling parameters (thanks to dl_new=1).
+         */
+        if (p->dl.runtime > 0) {
+                rq->curr->dl.dl_new = 1;
+                p->dl.runtime = 0;
+        }
+        update_curr_dl(rq);
+}
+
+#ifdef CONFIG_SMP
+
+static int find_later_rq(struct task_struct *task);
+
+static int
+select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
+{
+        struct task_struct *curr;
+        struct rq *rq;
+
+        if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
+                goto out;
+
+        rq = cpu_rq(cpu);
+
+        rcu_read_lock();
+        curr = ACCESS_ONCE(rq->curr); /* unlocked access */
+
+        /*
+         * If we are dealing with a -deadline task, we must
+         * decide where to wake it up.
+         * If it has a later deadline and the current task
+         * on this rq can't move (provided the waking task
+         * can!) we prefer to send it somewhere else. On the
+         * other hand, if it has a shorter deadline, we
+         * try to make it stay here, it might be important.
+         */
+        if (unlikely(dl_task(curr)) &&
+            (curr->nr_cpus_allowed < 2 ||
+             !dl_entity_preempt(&p->dl, &curr->dl)) &&
+            (p->nr_cpus_allowed > 1)) {
+                int target = find_later_rq(p);
+
+                if (target != -1)
+                        cpu = target;
+        }
+        rcu_read_unlock();
+
+out:
+        return cpu;
+}
+
+static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
+{
+        /*
+         * Current can't be migrated, useless to reschedule,
+         * let's hope p can move out.
+         */
+        if (rq->curr->nr_cpus_allowed == 1 ||
+            cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
+                return;
+
+        /*
+         * p is migratable, so let's not schedule it and
+         * see if it is pushed or pulled somewhere else.
+         */
+        if (p->nr_cpus_allowed != 1 &&
+            cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
+                return;
+
+        resched_task(rq->curr);
+}
+
+#endif /* CONFIG_SMP */
+
+/*
+ * Only called when both the current and waking task are -deadline
+ * tasks.
+ */
+static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
+                                  int flags)
+{
+        if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
+                resched_task(rq->curr);
+                return;
+        }
+
+#ifdef CONFIG_SMP
+        /*
+         * In the unlikely case current and p have the same deadline
+         * let us try to decide what's the best thing to do...
+         */
+        if ((p->dl.deadline == rq->curr->dl.deadline) &&
+            !test_tsk_need_resched(rq->curr))
+                check_preempt_equal_dl(rq, p);
+#endif /* CONFIG_SMP */
+}
+
+#ifdef CONFIG_SCHED_HRTICK
+static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
+{
+        s64 delta = p->dl.dl_runtime - p->dl.runtime;
+
+        if (delta > 10000)
+                hrtick_start(rq, p->dl.runtime);
+}
+#endif
+
+static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
+                                                   struct dl_rq *dl_rq)
+{
+        struct rb_node *left = dl_rq->rb_leftmost;
+
+        if (!left)
+                return NULL;
+
+        return rb_entry(left, struct sched_dl_entity, rb_node);
+}
+
+struct task_struct *pick_next_task_dl(struct rq *rq)
+{
+        struct sched_dl_entity *dl_se;
+        struct task_struct *p;
+        struct dl_rq *dl_rq;
+
+        dl_rq = &rq->dl;
+
+        if (unlikely(!dl_rq->dl_nr_running))
+                return NULL;
+
+        dl_se = pick_next_dl_entity(rq, dl_rq);
+        BUG_ON(!dl_se);
+
+        p = dl_task_of(dl_se);
+        p->se.exec_start = rq_clock_task(rq);
+
+        /* Running task will never be pushed. */
+       dequeue_pushable_dl_task(rq, p);
+
+#ifdef CONFIG_SCHED_HRTICK
+        if (hrtick_enabled(rq))
+                start_hrtick_dl(rq, p);
+#endif
+
+#ifdef CONFIG_SMP
+        rq->post_schedule = has_pushable_dl_tasks(rq);
+#endif /* CONFIG_SMP */
+
+        return p;
+}
+
+static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
+{
+        update_curr_dl(rq);
+
+        if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
+                enqueue_pushable_dl_task(rq, p);
+}
+
+static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
+{
+        update_curr_dl(rq);
+
+#ifdef CONFIG_SCHED_HRTICK
+        if (hrtick_enabled(rq) && queued && p->dl.runtime > 0)
+                start_hrtick_dl(rq, p);
+#endif
+}
+
+static void task_fork_dl(struct task_struct *p)
+{
+        /*
+         * SCHED_DEADLINE tasks cannot fork and this is achieved through
+         * sched_fork()
+         */
+}
+
+static void task_dead_dl(struct task_struct *p)
+{
+        struct hrtimer *timer = &p->dl.dl_timer;
+        struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
+
+        /*
+         * Since we are TASK_DEAD we won't slip out of the domain!
+         */
+        raw_spin_lock_irq(&dl_b->lock);
+        dl_b->total_bw -= p->dl.dl_bw;
+        raw_spin_unlock_irq(&dl_b->lock);
+
+        hrtimer_cancel(timer);
+}
+
+static void set_curr_task_dl(struct rq *rq)
+{
+        struct task_struct *p = rq->curr;
+
+        p->se.exec_start = rq_clock_task(rq);
+
+        /* You can't push away the running task */
+        dequeue_pushable_dl_task(rq, p);
+}
+
+#ifdef CONFIG_SMP
+
+/* Only try algorithms three times */
+#define DL_MAX_TRIES 3
+
+static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
+{
+        if (!task_running(rq, p) &&
+            (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
+            (p->nr_cpus_allowed > 1))
+                return 1;
+
+        return 0;
+}
+
+/* Returns the second earliest -deadline task, NULL otherwise */
+static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu)
+{
+        struct rb_node *next_node = rq->dl.rb_leftmost;
+        struct sched_dl_entity *dl_se;
+        struct task_struct *p = NULL;
+
+next_node:
+        next_node = rb_next(next_node);
+        if (next_node) {
+                dl_se = rb_entry(next_node, struct sched_dl_entity, rb_node);
+                p = dl_task_of(dl_se);
+
+                if (pick_dl_task(rq, p, cpu))
+                        return p;
+
+                goto next_node;
+        }
+
+        return NULL;
+}
+
+static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
+
+static int find_later_rq(struct task_struct *task)
+{
+        struct sched_domain *sd;
+        struct cpumask *later_mask = __get_cpu_var(local_cpu_mask_dl);
+        int this_cpu = smp_processor_id();
+        int best_cpu, cpu = task_cpu(task);
+
+        /* Make sure the mask is initialized first */
+        if (unlikely(!later_mask))
+                return -1;
+
+        if (task->nr_cpus_allowed == 1)
+                return -1;
+
+        best_cpu = cpudl_find(&task_rq(task)->rd->cpudl,
+                        task, later_mask);
+        if (best_cpu == -1)
+                return -1;
+
+        /*
+         * If we are here, some target has been found,
+         * the most suitable of which is cached in best_cpu.
+         * This is, among the runqueues where the current tasks
+         * have later deadlines than the task's one, the rq
+         * with the latest possible one.
+         *
+         * Now we check how well this matches with task's
+         * affinity and system topology.
+         *
+         * The last cpu where the task run is our first
+         * guess, since it is most likely cache-hot there.
+         */
+        if (cpumask_test_cpu(cpu, later_mask))
+                return cpu;
+        /*
+         * Check if this_cpu is to be skipped (i.e., it is
+         * not in the mask) or not.
+         */
+        if (!cpumask_test_cpu(this_cpu, later_mask))
+                this_cpu = -1;
+
+        rcu_read_lock();
+        for_each_domain(cpu, sd) {
+                if (sd->flags & SD_WAKE_AFFINE) {
+
+                        /*
+                         * If possible, preempting this_cpu is
+                         * cheaper than migrating.
+                         */
+                        if (this_cpu != -1 &&
+                            cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
+                                rcu_read_unlock();
+                                return this_cpu;
+                        }
+
+                        /*
+                         * Last chance: if best_cpu is valid and is
+                         * in the mask, that becomes our choice.
+                         */
+                        if (best_cpu < nr_cpu_ids &&
+                            cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
+                                rcu_read_unlock();
+                                return best_cpu;
+                        }
+                }
+        }
+        rcu_read_unlock();
+
+        /*
+         * At this point, all our guesses failed, we just return
+         * 'something', and let the caller sort the things out.
+         */
+        if (this_cpu != -1)
+                return this_cpu;
+
+        cpu = cpumask_any(later_mask);
+        if (cpu < nr_cpu_ids)
+                return cpu;
+
+        return -1;
+}
+
+/* Locks the rq it finds */
+static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
+{
+        struct rq *later_rq = NULL;
+        int tries;
+        int cpu;
+
+        for (tries = 0; tries < DL_MAX_TRIES; tries++) {
+                cpu = find_later_rq(task);
+
+                if ((cpu == -1) || (cpu == rq->cpu))
+                        break;
+
+                later_rq = cpu_rq(cpu);
+
+                /* Retry if something changed. */
+                if (double_lock_balance(rq, later_rq)) {
+                        if (unlikely(task_rq(task) != rq ||
+                                     !cpumask_test_cpu(later_rq->cpu,
+                                                       &task->cpus_allowed) ||
+                                     task_running(rq, task) || !task->on_rq)) {
+                                double_unlock_balance(rq, later_rq);
+                                later_rq = NULL;
+                                break;
+                        }
+                }
+
+                /*
+                 * If the rq we found has no -deadline task, or
+                 * its earliest one has a later deadline than our
+                 * task, the rq is a good one.
+                 */
+                if (!later_rq->dl.dl_nr_running ||
+                    dl_time_before(task->dl.deadline,
+                                   later_rq->dl.earliest_dl.curr))
+                        break;
+
+                /* Otherwise we try again. */
+                double_unlock_balance(rq, later_rq);
+                later_rq = NULL;
+        }
+
+        return later_rq;
+}
+
+static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
+{
+        struct task_struct *p;
+
+        if (!has_pushable_dl_tasks(rq))
+                return NULL;
+
+        p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
+                     struct task_struct, pushable_dl_tasks);
+
+        BUG_ON(rq->cpu != task_cpu(p));
+        BUG_ON(task_current(rq, p));
+        BUG_ON(p->nr_cpus_allowed <= 1);
+
+        BUG_ON(!p->on_rq);
+        BUG_ON(!dl_task(p));
+
+        return p;
+}
+
+/*
+ * See if the non running -deadline tasks on this rq
+ * can be sent to some other CPU where they can preempt
+ * and start executing.
+ */
+static int push_dl_task(struct rq *rq)
+{
+        struct task_struct *next_task;
+        struct rq *later_rq;
+
+        if (!rq->dl.overloaded)
+                return 0;
+
+        next_task = pick_next_pushable_dl_task(rq);
+        if (!next_task)
+                return 0;
+
+retry:
+        if (unlikely(next_task == rq->curr)) {
+                WARN_ON(1);
+                return 0;
+        }
+
+        /*
+         * If next_task preempts rq->curr, and rq->curr
+         * can move away, it makes sense to just reschedule
+         * without going further in pushing next_task.
+         */
+        if (dl_task(rq->curr) &&
+            dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
+            rq->curr->nr_cpus_allowed > 1) {
+                resched_task(rq->curr);
+                return 0;
+        }
+
+        /* We might release rq lock */
+        get_task_struct(next_task);
+
+        /* Will lock the rq it'll find */
+        later_rq = find_lock_later_rq(next_task, rq);
+        if (!later_rq) {
+                struct task_struct *task;
+
+                /*
+                 * We must check all this again, since
+                 * find_lock_later_rq releases rq->lock and it is
+                 * then possible that next_task has migrated.
+                 */
+                task = pick_next_pushable_dl_task(rq);
+                if (task_cpu(next_task) == rq->cpu && task == next_task) {
+                        /*
+                         * The task is still there. We don't try
+                         * again, some other cpu will pull it when ready.
+                         */
+                        dequeue_pushable_dl_task(rq, next_task);
+                        goto out;
+                }
+
+                if (!task)
+                        /* No more tasks */
+                        goto out;
+
+                put_task_struct(next_task);
+                next_task = task;
+                goto retry;
+        }
+
+        deactivate_task(rq, next_task, 0);
+        set_task_cpu(next_task, later_rq->cpu);
+        activate_task(later_rq, next_task, 0);
+
+        resched_task(later_rq->curr);
+
+        double_unlock_balance(rq, later_rq);
+
+out:
+        put_task_struct(next_task);
+
+        return 1;
+}
+
+static void push_dl_tasks(struct rq *rq)
+{
+        /* Terminates as it moves a -deadline task */
+        while (push_dl_task(rq))
+                ;
+}
+
+static int pull_dl_task(struct rq *this_rq)
+{
+        int this_cpu = this_rq->cpu, ret = 0, cpu;
+        struct task_struct *p;
+        struct rq *src_rq;
+        u64 dmin = LONG_MAX;
+
+        if (likely(!dl_overloaded(this_rq)))
+                return 0;
+
+        /*
+         * Match the barrier from dl_set_overloaded; this guarantees that if we
+         * see overloaded we must also see the dlo_mask bit.
+         */
+        smp_rmb();
+
+        for_each_cpu(cpu, this_rq->rd->dlo_mask) {
+                if (this_cpu == cpu)
+                        continue;
+
+                src_rq = cpu_rq(cpu);
+
+                /*
+                 * It looks racy, abd it is! However, as in sched_rt.c,
+                 * we are fine with this.
+                 */
+                if (this_rq->dl.dl_nr_running &&
+                    dl_time_before(this_rq->dl.earliest_dl.curr,
+                                   src_rq->dl.earliest_dl.next))
+                        continue;
+
+                /* Might drop this_rq->lock */
+                double_lock_balance(this_rq, src_rq);
+
+                /*
+                 * If there are no more pullable tasks on the
+                 * rq, we're done with it.
+                 */
+                if (src_rq->dl.dl_nr_running <= 1)
+                        goto skip;
+
+                p = pick_next_earliest_dl_task(src_rq, this_cpu);
+
+                /*
+                 * We found a task to be pulled if:
+                 *  - it preempts our current (if there's one),
+                 *  - it will preempt the last one we pulled (if any).
+                 */
+                if (p && dl_time_before(p->dl.deadline, dmin) &&
+                    (!this_rq->dl.dl_nr_running ||
+                     dl_time_before(p->dl.deadline,
+                                    this_rq->dl.earliest_dl.curr))) {
+                        WARN_ON(p == src_rq->curr);
+                        WARN_ON(!p->on_rq);
+
+                        /*
+                         * Then we pull iff p has actually an earlier
+                         * deadline than the current task of its runqueue.
+                         */
+                        if (dl_time_before(p->dl.deadline,
+                                           src_rq->curr->dl.deadline))
+                                goto skip;
+
+                        ret = 1;
+
+                        deactivate_task(src_rq, p, 0);
+                        set_task_cpu(p, this_cpu);
+                        activate_task(this_rq, p, 0);
+                        dmin = p->dl.deadline;
+
+                        /* Is there any other task even earlier? */
+                }
+skip:
+                double_unlock_balance(this_rq, src_rq);
+        }
+
+        return ret;
+}
+
+static void pre_schedule_dl(struct rq *rq, struct task_struct *prev)
+{
+        /* Try to pull other tasks here */
+        if (dl_task(prev))
+                pull_dl_task(rq);
+}
+
+static void post_schedule_dl(struct rq *rq)
+{
+        push_dl_tasks(rq);
+}
+
+/*
+ * Since the task is not running and a reschedule is not going to happen
+ * anytime soon on its runqueue, we try pushing it away now.
+ */
+static void task_woken_dl(struct rq *rq, struct task_struct *p)
+{
+        if (!task_running(rq, p) &&
+            !test_tsk_need_resched(rq->curr) &&
+            has_pushable_dl_tasks(rq) &&
+            p->nr_cpus_allowed > 1 &&
+            dl_task(rq->curr) &&
+            (rq->curr->nr_cpus_allowed < 2 ||
+             dl_entity_preempt(&rq->curr->dl, &p->dl))) {
+                push_dl_tasks(rq);
+        }
+}
+
+static void set_cpus_allowed_dl(struct task_struct *p,
+                                const struct cpumask *new_mask)
+{
+        struct rq *rq;
+        int weight;
+
+        BUG_ON(!dl_task(p));
+
+        /*
+         * Update only if the task is actually running (i.e.,
+         * it is on the rq AND it is not throttled).
+         */
+        if (!on_dl_rq(&p->dl))
+                return;
+
+        weight = cpumask_weight(new_mask);
+
+        /*
+         * Only update if the process changes its state from whether it
+         * can migrate or not.
+         */
+        if ((p->nr_cpus_allowed > 1) == (weight > 1))
+                return;
+
+        rq = task_rq(p);
+
+        /*
+         * The process used to be able to migrate OR it can now migrate
+         */
+        if (weight <= 1) {
+                if (!task_current(rq, p))
+                        dequeue_pushable_dl_task(rq, p);
+                BUG_ON(!rq->dl.dl_nr_migratory);
+                rq->dl.dl_nr_migratory--;
+        } else {
+                if (!task_current(rq, p))
+                        enqueue_pushable_dl_task(rq, p);
+                rq->dl.dl_nr_migratory++;
+        }
+
+        update_dl_migration(&rq->dl);
+}
+
+/* Assumes rq->lock is held */
+static void rq_online_dl(struct rq *rq)
+{
+        if (rq->dl.overloaded)
+                dl_set_overload(rq);
+
+        if (rq->dl.dl_nr_running > 0)
+                cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
+}
+
+/* Assumes rq->lock is held */
+static void rq_offline_dl(struct rq *rq)
+{
+        if (rq->dl.overloaded)
+                dl_clear_overload(rq);
+
+        cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
+}
+
+void init_sched_dl_class(void)
+{
+        unsigned int i;
+
+        for_each_possible_cpu(i)
+                zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
+                                        GFP_KERNEL, cpu_to_node(i));
+}
+
+#endif /* CONFIG_SMP */
+
+static void switched_from_dl(struct rq *rq, struct task_struct *p)
+{
+        if (hrtimer_active(&p->dl.dl_timer) && !dl_policy(p->policy))
+                hrtimer_try_to_cancel(&p->dl.dl_timer);
+
+#ifdef CONFIG_SMP
+        /*
+         * Since this might be the only -deadline task on the rq,
+         * this is the right place to try to pull some other one
+         * from an overloaded cpu, if any.
+         */
+        if (!rq->dl.dl_nr_running)
+                pull_dl_task(rq);
+#endif
+}
+
+/*
+ * When switching to -deadline, we may overload the rq, then
+ * we try to push someone off, if possible.
+ */
+static void switched_to_dl(struct rq *rq, struct task_struct *p)
+{
+        int check_resched = 1;
+
+        /*
+         * If p is throttled, don't consider the possibility
+         * of preempting rq->curr, the check will be done right
+         * after its runtime will get replenished.
+         */
+        if (unlikely(p->dl.dl_throttled))
+                return;
+
+        if (p->on_rq || rq->curr != p) {
+#ifdef CONFIG_SMP
+                if (rq->dl.overloaded && push_dl_task(rq) && rq != task_rq(p))
+                        /* Only reschedule if pushing failed */
+                        check_resched = 0;
+#endif /* CONFIG_SMP */
+                if (check_resched && task_has_dl_policy(rq->curr))
+                        check_preempt_curr_dl(rq, p, 0);
+        }
+}
+
+/*
+ * If the scheduling parameters of a -deadline task changed,
+ * a push or pull operation might be needed.
+ */
+static void prio_changed_dl(struct rq *rq, struct task_struct *p,
+                            int oldprio)
+{
+        if (p->on_rq || rq->curr == p) {
+#ifdef CONFIG_SMP
+                /*
+                 * This might be too much, but unfortunately
+                 * we don't have the old deadline value, and
+                 * we can't argue if the task is increasing
+                 * or lowering its prio, so...
+                 */
+                if (!rq->dl.overloaded)
+                        pull_dl_task(rq);
+
+                /*
+                 * If we now have a earlier deadline task than p,
+                 * then reschedule, provided p is still on this
+                 * runqueue.
+                 */
+                if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline) &&
+                    rq->curr == p)
+                        resched_task(p);
+#else
+                /*
+                 * Again, we don't know if p has a earlier
+                 * or later deadline, so let's blindly set a
+                 * (maybe not needed) rescheduling point.
+                 */
+                resched_task(p);
+#endif /* CONFIG_SMP */
+        } else
+                switched_to_dl(rq, p);
+}
+
+const struct sched_class dl_sched_class = {
+        .next                   = &rt_sched_class,
+        .enqueue_task           = enqueue_task_dl,
+        .dequeue_task           = dequeue_task_dl,
+        .yield_task             = yield_task_dl,
+
+        .check_preempt_curr     = check_preempt_curr_dl,
+
+        .pick_next_task         = pick_next_task_dl,
+        .put_prev_task          = put_prev_task_dl,
+
+#ifdef CONFIG_SMP
+        .select_task_rq         = select_task_rq_dl,
+        .set_cpus_allowed       = set_cpus_allowed_dl,
+        .rq_online              = rq_online_dl,
+        .rq_offline             = rq_offline_dl,
+        .pre_schedule           = pre_schedule_dl,
+        .post_schedule          = post_schedule_dl,
+        .task_woken             = task_woken_dl,
+#endif
+
+        .set_curr_task          = set_curr_task_dl,
+        .task_tick              = task_tick_dl,
+        .task_fork              = task_fork_dl,
+        .task_dead              = task_dead_dl,
+
+        .prio_changed           = prio_changed_dl,
+        .switched_from          = switched_from_dl,
+        .switched_to            = switched_to_dl,
+};