1 files changed, 305 insertions, 174 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index b28114478b82..a04a436af8cc 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -54,8 +54,14 @@ static int __init sched_dl_sysctl_init(void)
 late_initcall(sched_dl_sysctl_init);
 #endif
 
+static bool dl_server(struct sched_dl_entity *dl_se)
+{
+	return dl_se->dl_server;
+}
+
 static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
 {
+	BUG_ON(dl_server(dl_se));
 	return container_of(dl_se, struct task_struct, dl);
 }
 
@@ -64,12 +70,19 @@ 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)
+static inline struct rq *rq_of_dl_se(struct sched_dl_entity *dl_se)
 {
-	struct task_struct *p = dl_task_of(dl_se);
-	struct rq *rq = task_rq(p);
+	struct rq *rq = dl_se->rq;
+
+	if (!dl_server(dl_se))
+		rq = task_rq(dl_task_of(dl_se));
+
+	return rq;
+}
 
-	return &rq->dl;
+static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
+{
+	return &rq_of_dl_se(dl_se)->dl;
 }
 
 static inline int on_dl_rq(struct sched_dl_entity *dl_se)
@@ -335,6 +348,8 @@ static void dl_change_utilization(struct task_struct *p, u64 new_bw)
 	__add_rq_bw(new_bw, &rq->dl);
 }
 
+static void __dl_clear_params(struct sched_dl_entity *dl_se);
+
 /*
  * The utilization of a task cannot be immediately removed from
  * the rq active utilization (running_bw) when the task blocks.
@@ -389,12 +404,11 @@ static void dl_change_utilization(struct task_struct *p, u64 new_bw)
  * up, and checks if the task is still in the "ACTIVE non contending"
  * state or not (in the second case, it updates running_bw).
  */
-static void task_non_contending(struct task_struct *p)
+static void task_non_contending(struct sched_dl_entity *dl_se)
 {
-	struct sched_dl_entity *dl_se = &p->dl;
 	struct hrtimer *timer = &dl_se->inactive_timer;
-	struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
-	struct rq *rq = rq_of_dl_rq(dl_rq);
+	struct rq *rq = rq_of_dl_se(dl_se);
+	struct dl_rq *dl_rq = &rq->dl;
 	s64 zerolag_time;
 
 	/*
@@ -424,24 +438,33 @@ static void task_non_contending(struct task_struct *p)
 	 * utilization now, instead of starting a timer
 	 */
 	if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {
-		if (dl_task(p))
+		if (dl_server(dl_se)) {
 			sub_running_bw(dl_se, dl_rq);
-		if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
-			struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
-
-			if (READ_ONCE(p->__state) == TASK_DEAD)
-				sub_rq_bw(&p->dl, &rq->dl);
-			raw_spin_lock(&dl_b->lock);
-			__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
-			raw_spin_unlock(&dl_b->lock);
-			__dl_clear_params(p);
+		} else {
+			struct task_struct *p = dl_task_of(dl_se);
+
+			if (dl_task(p))
+				sub_running_bw(dl_se, dl_rq);
+
+			if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
+				struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
+
+				if (READ_ONCE(p->__state) == TASK_DEAD)
+					sub_rq_bw(dl_se, &rq->dl);
+				raw_spin_lock(&dl_b->lock);
+				__dl_sub(dl_b, dl_se->dl_bw, dl_bw_cpus(task_cpu(p)));
+				raw_spin_unlock(&dl_b->lock);
+				__dl_clear_params(dl_se);
+			}
 		}
 
 		return;
 	}
 
 	dl_se->dl_non_contending = 1;
-	get_task_struct(p);
+	if (!dl_server(dl_se))
+		get_task_struct(dl_task_of(dl_se));
+
 	hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL_HARD);
 }
 
@@ -468,8 +491,10 @@ static void task_contending(struct sched_dl_entity *dl_se, int flags)
 		 * will not touch the rq's active utilization,
 		 * so we are still safe.
 		 */
-		if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1)
-			put_task_struct(dl_task_of(dl_se));
+		if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1) {
+			if (!dl_server(dl_se))
+				put_task_struct(dl_task_of(dl_se));
+		}
 	} else {
 		/*
 		 * Since "dl_non_contending" is not set, the
@@ -482,10 +507,8 @@ static void task_contending(struct sched_dl_entity *dl_se, int flags)
 	}
 }
 
-static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
+static inline int is_leftmost(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
 {
-	struct sched_dl_entity *dl_se = &p->dl;
-
 	return rb_first_cached(&dl_rq->root) == &dl_se->rb_node;
 }
 
@@ -737,8 +760,10 @@ static inline void deadline_queue_pull_task(struct rq *rq)
 }
 #endif /* CONFIG_SMP */
 
+static void
+enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags);
 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 dequeue_dl_entity(struct sched_dl_entity *dl_se, int flags);
 static void wakeup_preempt_dl(struct rq *rq, struct task_struct *p, int flags);
 
 static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
@@ -986,8 +1011,7 @@ static inline bool dl_is_implicit(struct sched_dl_entity *dl_se)
  */
 static void update_dl_entity(struct sched_dl_entity *dl_se)
 {
-	struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
-	struct rq *rq = rq_of_dl_rq(dl_rq);
+	struct rq *rq = rq_of_dl_se(dl_se);
 
 	if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
 	    dl_entity_overflow(dl_se, rq_clock(rq))) {
@@ -1018,11 +1042,11 @@ static inline u64 dl_next_period(struct sched_dl_entity *dl_se)
  * actually started or not (i.e., the replenishment instant is in
  * the future or in the past).
  */
-static int start_dl_timer(struct task_struct *p)
+static int start_dl_timer(struct sched_dl_entity *dl_se)
 {
-	struct sched_dl_entity *dl_se = &p->dl;
 	struct hrtimer *timer = &dl_se->dl_timer;
-	struct rq *rq = task_rq(p);
+	struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+	struct rq *rq = rq_of_dl_rq(dl_rq);
 	ktime_t now, act;
 	s64 delta;
 
@@ -1056,13 +1080,33 @@ static int start_dl_timer(struct task_struct *p)
 	 * and observe our state.
 	 */
 	if (!hrtimer_is_queued(timer)) {
-		get_task_struct(p);
+		if (!dl_server(dl_se))
+			get_task_struct(dl_task_of(dl_se));
 		hrtimer_start(timer, act, HRTIMER_MODE_ABS_HARD);
 	}
 
 	return 1;
 }
 
+static void __push_dl_task(struct rq *rq, struct rq_flags *rf)
+{
+#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)) {
+		/*
+		 * Nothing relies on rq->lock after this, so its safe to drop
+		 * rq->lock.
+		 */
+		rq_unpin_lock(rq, rf);
+		push_dl_task(rq);
+		rq_repin_lock(rq, rf);
+	}
+#endif
+}
+
 /*
  * 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
@@ -1081,10 +1125,34 @@ 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 task_struct *p;
 	struct rq_flags rf;
 	struct rq *rq;
 
+	if (dl_server(dl_se)) {
+		struct rq *rq = rq_of_dl_se(dl_se);
+		struct rq_flags rf;
+
+		rq_lock(rq, &rf);
+		if (dl_se->dl_throttled) {
+			sched_clock_tick();
+			update_rq_clock(rq);
+
+			if (dl_se->server_has_tasks(dl_se)) {
+				enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH);
+				resched_curr(rq);
+				__push_dl_task(rq, &rf);
+			} else {
+				replenish_dl_entity(dl_se);
+			}
+
+		}
+		rq_unlock(rq, &rf);
+
+		return HRTIMER_NORESTART;
+	}
+
+	p = dl_task_of(dl_se);
 	rq = task_rq_lock(p, &rf);
 
 	/*
@@ -1155,21 +1223,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 	else
 		resched_curr(rq);
 
-#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)) {
-		/*
-		 * Nothing relies on rq->lock after this, so its safe to drop
-		 * rq->lock.
-		 */
-		rq_unpin_lock(rq, &rf);
-		push_dl_task(rq);
-		rq_repin_lock(rq, &rf);
-	}
-#endif
+	__push_dl_task(rq, &rf);
 
 unlock:
 	task_rq_unlock(rq, p, &rf);
@@ -1183,7 +1237,7 @@ unlock:
 	return HRTIMER_NORESTART;
 }
 
-void init_dl_task_timer(struct sched_dl_entity *dl_se)
+static void init_dl_task_timer(struct sched_dl_entity *dl_se)
 {
 	struct hrtimer *timer = &dl_se->dl_timer;
 
@@ -1211,12 +1265,11 @@ void init_dl_task_timer(struct sched_dl_entity *dl_se)
  */
 static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
 {
-	struct task_struct *p = dl_task_of(dl_se);
-	struct rq *rq = rq_of_dl_rq(dl_rq_of_se(dl_se));
+	struct rq *rq = rq_of_dl_se(dl_se);
 
 	if (dl_time_before(dl_se->deadline, rq_clock(rq)) &&
 	    dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
-		if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(p)))
+		if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se)))
 			return;
 		dl_se->dl_throttled = 1;
 		if (dl_se->runtime > 0)
@@ -1267,44 +1320,19 @@ static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se)
 	return (delta * u_act) >> BW_SHIFT;
 }
 
-/*
- * 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)
+static inline void
+update_stats_dequeue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
+                        int flags);
+static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64 delta_exec)
 {
-	struct task_struct *curr = rq->curr;
-	struct sched_dl_entity *dl_se = &curr->dl;
-	u64 delta_exec, scaled_delta_exec;
-	int cpu = cpu_of(rq);
-	u64 now;
-
-	if (!dl_task(curr) || !on_dl_rq(dl_se))
-		return;
+	s64 scaled_delta_exec;
 
-	/*
-	 * 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.
-	 */
-	now = rq_clock_task(rq);
-	delta_exec = now - curr->se.exec_start;
-	if (unlikely((s64)delta_exec <= 0)) {
+	if (unlikely(delta_exec <= 0)) {
 		if (unlikely(dl_se->dl_yielded))
 			goto throttle;
 		return;
 	}
 
-	schedstat_set(curr->stats.exec_max,
-		      max(curr->stats.exec_max, delta_exec));
-
-	trace_sched_stat_runtime(curr, delta_exec, 0);
-
-	update_current_exec_runtime(curr, now, delta_exec);
-
 	if (dl_entity_is_special(dl_se))
 		return;
 
@@ -1316,10 +1344,9 @@ static void update_curr_dl(struct rq *rq)
 	 * according to current frequency and CPU maximum capacity.
 	 */
 	if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM)) {
-		scaled_delta_exec = grub_reclaim(delta_exec,
-						 rq,
-						 &curr->dl);
+		scaled_delta_exec = grub_reclaim(delta_exec, rq, dl_se);
 	} else {
+		int cpu = cpu_of(rq);
 		unsigned long scale_freq = arch_scale_freq_capacity(cpu);
 		unsigned long scale_cpu = arch_scale_cpu_capacity(cpu);
 
@@ -1338,11 +1365,20 @@ throttle:
 		    (dl_se->flags & SCHED_FLAG_DL_OVERRUN))
 			dl_se->dl_overrun = 1;
 
-		__dequeue_task_dl(rq, curr, 0);
-		if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(curr)))
-			enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
+		dequeue_dl_entity(dl_se, 0);
+		if (!dl_server(dl_se)) {
+			update_stats_dequeue_dl(&rq->dl, dl_se, 0);
+			dequeue_pushable_dl_task(rq, dl_task_of(dl_se));
+		}
+
+		if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se))) {
+			if (dl_server(dl_se))
+				enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH);
+			else
+				enqueue_task_dl(rq, dl_task_of(dl_se), ENQUEUE_REPLENISH);
+		}
 
-		if (!is_leftmost(curr, &rq->dl))
+		if (!is_leftmost(dl_se, &rq->dl))
 			resched_curr(rq);
 	}
 
@@ -1372,20 +1408,82 @@ throttle:
 	}
 }
 
+void dl_server_update(struct sched_dl_entity *dl_se, s64 delta_exec)
+{
+	update_curr_dl_se(dl_se->rq, dl_se, delta_exec);
+}
+
+void dl_server_start(struct sched_dl_entity *dl_se)
+{
+	if (!dl_server(dl_se)) {
+		dl_se->dl_server = 1;
+		setup_new_dl_entity(dl_se);
+	}
+	enqueue_dl_entity(dl_se, ENQUEUE_WAKEUP);
+}
+
+void dl_server_stop(struct sched_dl_entity *dl_se)
+{
+	dequeue_dl_entity(dl_se, DEQUEUE_SLEEP);
+}
+
+void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq,
+		    dl_server_has_tasks_f has_tasks,
+		    dl_server_pick_f pick)
+{
+	dl_se->rq = rq;
+	dl_se->server_has_tasks = has_tasks;
+	dl_se->server_pick = pick;
+}
+
+/*
+ * 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;
+	s64 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 = update_curr_common(rq);
+	update_curr_dl_se(rq, dl_se, delta_exec);
+}
+
 static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
 {
 	struct sched_dl_entity *dl_se = container_of(timer,
 						     struct sched_dl_entity,
 						     inactive_timer);
-	struct task_struct *p = dl_task_of(dl_se);
+	struct task_struct *p = NULL;
 	struct rq_flags rf;
 	struct rq *rq;
 
-	rq = task_rq_lock(p, &rf);
+	if (!dl_server(dl_se)) {
+		p = dl_task_of(dl_se);
+		rq = task_rq_lock(p, &rf);
+	} else {
+		rq = dl_se->rq;
+		rq_lock(rq, &rf);
+	}
 
 	sched_clock_tick();
 	update_rq_clock(rq);
 
+	if (dl_server(dl_se))
+		goto no_task;
+
 	if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
 		struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
 
@@ -1398,23 +1496,30 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
 		raw_spin_lock(&dl_b->lock);
 		__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
 		raw_spin_unlock(&dl_b->lock);
-		__dl_clear_params(p);
+		__dl_clear_params(dl_se);
 
 		goto unlock;
 	}
+
+no_task:
 	if (dl_se->dl_non_contending == 0)
 		goto unlock;
 
 	sub_running_bw(dl_se, &rq->dl);
 	dl_se->dl_non_contending = 0;
 unlock:
-	task_rq_unlock(rq, p, &rf);
-	put_task_struct(p);
+
+	if (!dl_server(dl_se)) {
+		task_rq_unlock(rq, p, &rf);
+		put_task_struct(p);
+	} else {
+		rq_unlock(rq, &rf);
+	}
 
 	return HRTIMER_NORESTART;
 }
 
-void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se)
+static void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se)
 {
 	struct hrtimer *timer = &dl_se->inactive_timer;
 
@@ -1472,10 +1577,8 @@ static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
 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++;
 	add_nr_running(rq_of_dl_rq(dl_rq), 1);
 
@@ -1485,9 +1588,6 @@ void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *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--;
 	sub_nr_running(rq_of_dl_rq(dl_rq), 1);
@@ -1609,6 +1709,41 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
 	update_stats_enqueue_dl(dl_rq_of_se(dl_se), dl_se, flags);
 
 	/*
+	 * Check if a constrained deadline task was activated
+	 * after the deadline but before the next period.
+	 * If that is the case, the task will be throttled and
+	 * the replenishment timer will be set to the next period.
+	 */
+	if (!dl_se->dl_throttled && !dl_is_implicit(dl_se))
+		dl_check_constrained_dl(dl_se);
+
+	if (flags & (ENQUEUE_RESTORE|ENQUEUE_MIGRATING)) {
+		struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+
+		add_rq_bw(dl_se, dl_rq);
+		add_running_bw(dl_se, dl_rq);
+	}
+
+	/*
+	 * If p is throttled, we do not enqueue it. 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.
+	 * However, the active utilization does not depend on the fact
+	 * that the task is on the runqueue or not (but depends on the
+	 * task's state - in GRUB parlance, "inactive" vs "active contending").
+	 * In other words, even if a task is throttled its utilization must
+	 * be counted in the active utilization; hence, we need to call
+	 * add_running_bw().
+	 */
+	if (dl_se->dl_throttled && !(flags & ENQUEUE_REPLENISH)) {
+		if (flags & ENQUEUE_WAKEUP)
+			task_contending(dl_se, flags);
+
+		return;
+	}
+
+	/*
 	 * 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.
@@ -1619,17 +1754,35 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
 	} else if (flags & ENQUEUE_REPLENISH) {
 		replenish_dl_entity(dl_se);
 	} else if ((flags & ENQUEUE_RESTORE) &&
-		  dl_time_before(dl_se->deadline,
-				 rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) {
+		   dl_time_before(dl_se->deadline, rq_clock(rq_of_dl_se(dl_se)))) {
 		setup_new_dl_entity(dl_se);
 	}
 
 	__enqueue_dl_entity(dl_se);
 }
 
-static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
+static void dequeue_dl_entity(struct sched_dl_entity *dl_se, int flags)
 {
 	__dequeue_dl_entity(dl_se);
+
+	if (flags & (DEQUEUE_SAVE|DEQUEUE_MIGRATING)) {
+		struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
+
+		sub_running_bw(dl_se, dl_rq);
+		sub_rq_bw(dl_se, dl_rq);
+	}
+
+	/*
+	 * This check allows to start the inactive timer (or to immediately
+	 * decrease the active utilization, if needed) in two cases:
+	 * when the task blocks and when it is terminating
+	 * (p->state == TASK_DEAD). We can handle the two cases in the same
+	 * way, because from GRUB's point of view the same thing is happening
+	 * (the task moves from "active contending" to "active non contending"
+	 * or "inactive")
+	 */
+	if (flags & DEQUEUE_SLEEP)
+		task_non_contending(dl_se);
 }
 
 static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
@@ -1674,76 +1827,31 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
 		return;
 	}
 
-	/*
-	 * Check if a constrained deadline task was activated
-	 * after the deadline but before the next period.
-	 * If that is the case, the task will be throttled and
-	 * the replenishment timer will be set to the next period.
-	 */
-	if (!p->dl.dl_throttled && !dl_is_implicit(&p->dl))
-		dl_check_constrained_dl(&p->dl);
-
-	if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) {
-		add_rq_bw(&p->dl, &rq->dl);
-		add_running_bw(&p->dl, &rq->dl);
-	}
-
-	/*
-	 * If p is throttled, we do not enqueue it. 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.
-	 * However, the active utilization does not depend on the fact
-	 * that the task is on the runqueue or not (but depends on the
-	 * task's state - in GRUB parlance, "inactive" vs "active contending").
-	 * In other words, even if a task is throttled its utilization must
-	 * be counted in the active utilization; hence, we need to call
-	 * add_running_bw().
-	 */
-	if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) {
-		if (flags & ENQUEUE_WAKEUP)
-			task_contending(&p->dl, flags);
-
-		return;
-	}
-
 	check_schedstat_required();
 	update_stats_wait_start_dl(dl_rq_of_se(&p->dl), &p->dl);
 
+	if (p->on_rq == TASK_ON_RQ_MIGRATING)
+		flags |= ENQUEUE_MIGRATING;
+
 	enqueue_dl_entity(&p->dl, flags);
 
-	if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
-		enqueue_pushable_dl_task(rq, p);
-}
+	if (dl_server(&p->dl))
+		return;
 
-static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
-{
-	update_stats_dequeue_dl(&rq->dl, &p->dl, flags);
-	dequeue_dl_entity(&p->dl);
-	dequeue_pushable_dl_task(rq, p);
+	if (!task_current(rq, p) && !p->dl.dl_throttled && 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)
 {
 	update_curr_dl(rq);
-	__dequeue_task_dl(rq, p, flags);
 
-	if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) {
-		sub_running_bw(&p->dl, &rq->dl);
-		sub_rq_bw(&p->dl, &rq->dl);
-	}
+	if (p->on_rq == TASK_ON_RQ_MIGRATING)
+		flags |= DEQUEUE_MIGRATING;
 
-	/*
-	 * This check allows to start the inactive timer (or to immediately
-	 * decrease the active utilization, if needed) in two cases:
-	 * when the task blocks and when it is terminating
-	 * (p->state == TASK_DEAD). We can handle the two cases in the same
-	 * way, because from GRUB's point of view the same thing is happening
-	 * (the task moves from "active contending" to "active non contending"
-	 * or "inactive")
-	 */
-	if (flags & DEQUEUE_SLEEP)
-		task_non_contending(p);
+	dequeue_dl_entity(&p->dl, flags);
+	if (!p->dl.dl_throttled && !dl_server(&p->dl))
+		dequeue_pushable_dl_task(rq, p);
 }
 
 /*
@@ -1933,12 +2041,12 @@ static void wakeup_preempt_dl(struct rq *rq, struct task_struct *p,
 }
 
 #ifdef CONFIG_SCHED_HRTICK
-static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
+static void start_hrtick_dl(struct rq *rq, struct sched_dl_entity *dl_se)
 {
-	hrtick_start(rq, p->dl.runtime);
+	hrtick_start(rq, dl_se->runtime);
 }
 #else /* !CONFIG_SCHED_HRTICK */
-static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
+static void start_hrtick_dl(struct rq *rq, struct sched_dl_entity *dl_se)
 {
 }
 #endif
@@ -1958,9 +2066,6 @@ static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first)
 	if (!first)
 		return;
 
-	if (hrtick_enabled_dl(rq))
-		start_hrtick_dl(rq, p);
-
 	if (rq->curr->sched_class != &dl_sched_class)
 		update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
 
@@ -1983,12 +2088,25 @@ static struct task_struct *pick_task_dl(struct rq *rq)
 	struct dl_rq *dl_rq = &rq->dl;
 	struct task_struct *p;
 
+again:
 	if (!sched_dl_runnable(rq))
 		return NULL;
 
 	dl_se = pick_next_dl_entity(dl_rq);
 	WARN_ON_ONCE(!dl_se);
-	p = dl_task_of(dl_se);
+
+	if (dl_server(dl_se)) {
+		p = dl_se->server_pick(dl_se);
+		if (!p) {
+			WARN_ON_ONCE(1);
+			dl_se->dl_yielded = 1;
+			update_curr_dl_se(rq, dl_se, 0);
+			goto again;
+		}
+		p->dl_server = dl_se;
+	} else {
+		p = dl_task_of(dl_se);
+	}
 
 	return p;
 }
@@ -1998,9 +2116,15 @@ static struct task_struct *pick_next_task_dl(struct rq *rq)
 	struct task_struct *p;
 
 	p = pick_task_dl(rq);
-	if (p)
+	if (!p)
+		return p;
+
+	if (!p->dl_server)
 		set_next_task_dl(rq, p, true);
 
+	if (hrtick_enabled(rq))
+		start_hrtick_dl(rq, &p->dl);
+
 	return p;
 }
 
@@ -2038,8 +2162,8 @@ static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
 	 * be set and schedule() will start a new hrtick for the next task.
 	 */
 	if (hrtick_enabled_dl(rq) && queued && p->dl.runtime > 0 &&
-	    is_leftmost(p, &rq->dl))
-		start_hrtick_dl(rq, p);
+	    is_leftmost(&p->dl, &rq->dl))
+		start_hrtick_dl(rq, &p->dl);
 }
 
 static void task_fork_dl(struct task_struct *p)
@@ -2558,7 +2682,7 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p)
 	 * will reset the task parameters.
 	 */
 	if (task_on_rq_queued(p) && p->dl.dl_runtime)
-		task_non_contending(p);
+		task_non_contending(&p->dl);
 
 	/*
 	 * In case a task is setscheduled out from SCHED_DEADLINE we need to
@@ -2966,10 +3090,8 @@ bool __checkparam_dl(const struct sched_attr *attr)
 /*
  * This function clears the sched_dl_entity static params.
  */
-void __dl_clear_params(struct task_struct *p)
+static void __dl_clear_params(struct sched_dl_entity *dl_se)
 {
-	struct sched_dl_entity *dl_se = &p->dl;
-
 	dl_se->dl_runtime		= 0;
 	dl_se->dl_deadline		= 0;
 	dl_se->dl_period		= 0;
@@ -2981,12 +3103,21 @@ void __dl_clear_params(struct task_struct *p)
 	dl_se->dl_yielded		= 0;
 	dl_se->dl_non_contending	= 0;
 	dl_se->dl_overrun		= 0;
+	dl_se->dl_server		= 0;
 
 #ifdef CONFIG_RT_MUTEXES
 	dl_se->pi_se			= dl_se;
 #endif
 }
 
+void init_dl_entity(struct sched_dl_entity *dl_se)
+{
+	RB_CLEAR_NODE(&dl_se->rb_node);
+	init_dl_task_timer(dl_se);
+	init_dl_inactive_task_timer(dl_se);
+	__dl_clear_params(dl_se);
+}
+
 bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
 {
 	struct sched_dl_entity *dl_se = &p->dl;