| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Juri Lelli | 4086 | 41.41% | 17 | 14.17% |
| Luca Abeni | 1639 | 16.61% | 14 | 11.67% |
| Nico Pitre | 1403 | 14.22% | 1 | 0.83% |
| Dario Faggioli | 1141 | 11.56% | 3 | 2.50% |
| Wanpeng Li | 465 | 4.71% | 16 | 13.33% |
| Peter Zijlstra | 464 | 4.70% | 19 | 15.83% |
| Daniel Bristot de Oliveira | 272 | 2.76% | 5 | 4.17% |
| Kirill Tkhai | 65 | 0.66% | 6 | 5.00% |
| Ingo Molnar | 63 | 0.64% | 4 | 3.33% |
| Kirill V Tkhai | 58 | 0.59% | 6 | 5.00% |
| Vincent Guittot | 50 | 0.51% | 1 | 0.83% |
| Xunlei Pang | 48 | 0.49% | 3 | 2.50% |
| Davidlohr Bueso A | 40 | 0.41% | 1 | 0.83% |
| Byungchul Park | 16 | 0.16% | 2 | 1.67% |
| Matt Fleming | 11 | 0.11% | 1 | 0.83% |
| Wen Yang | 9 | 0.09% | 1 | 0.83% |
| Joel Fernandes | 8 | 0.08% | 1 | 0.83% |
| Stanislaw Gruszka | 5 | 0.05% | 1 | 0.83% |
| Srikar Dronamraju | 4 | 0.04% | 1 | 0.83% |
| Steven Rostedt | 3 | 0.03% | 2 | 1.67% |
| Thomas Gleixner | 2 | 0.02% | 1 | 0.83% |
| Tommaso Cucinotta | 2 | 0.02% | 1 | 0.83% |
| Sebastian Andrzej Siewior | 2 | 0.02% | 1 | 0.83% |
| Frédéric Weisbecker | 1 | 0.01% | 1 | 0.83% |
| Harald Gustafsson | 1 | 0.01% | 1 | 0.83% |
| T.Zhou | 1 | 0.01% | 1 | 0.83% |
| xiaofeng.yan | 1 | 0.01% | 1 | 0.83% |
| Andrea Parri | 1 | 0.01% | 1 | 0.83% |
| Greg Kroah-Hartman | 1 | 0.01% | 1 | 0.83% |
| John Stultz | 1 | 0.01% | 1 | 0.83% |
| Mathieu Malaterre | 1 | 0.01% | 1 | 0.83% |
| Jason Low | 1 | 0.01% | 1 | 0.83% |
| Tejun Heo | 1 | 0.01% | 1 | 0.83% |
| Viresh Kumar | 1 | 0.01% | 1 | 0.83% |
| Christoph Lameter | 1 | 0.01% | 1 | 0.83% |
| Total | 9868 | 120 |
// SPDX-License-Identifier: GPL-2.0 /* * 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 "pelt.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); } #ifdef CONFIG_SMP static inline struct dl_bw *dl_bw_of(int i) { RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), "sched RCU must be held"); return &cpu_rq(i)->rd->dl_bw; } static inline int dl_bw_cpus(int i) { struct root_domain *rd = cpu_rq(i)->rd; int cpus = 0; RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), "sched RCU must be held"); for_each_cpu_and(i, rd->span, cpu_active_mask) cpus++; return cpus; } #else static inline struct dl_bw *dl_bw_of(int i) { return &cpu_rq(i)->dl.dl_bw; } static inline int dl_bw_cpus(int i) { return 1; } #endif static inline void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq) { u64 old = dl_rq->running_bw; lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); dl_rq->running_bw += dl_bw; SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */ SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); /* kick cpufreq (see the comment in kernel/sched/sched.h). */ cpufreq_update_util(rq_of_dl_rq(dl_rq), 0); } static inline void __sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq) { u64 old = dl_rq->running_bw; lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); dl_rq->running_bw -= dl_bw; SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */ if (dl_rq->running_bw > old) dl_rq->running_bw = 0; /* kick cpufreq (see the comment in kernel/sched/sched.h). */ cpufreq_update_util(rq_of_dl_rq(dl_rq), 0); } static inline void __add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) { u64 old = dl_rq->this_bw; lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); dl_rq->this_bw += dl_bw; SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */ } static inline void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) { u64 old = dl_rq->this_bw; lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); dl_rq->this_bw -= dl_bw; SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */ if (dl_rq->this_bw > old) dl_rq->this_bw = 0; SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); } static inline void add_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) { if (!dl_entity_is_special(dl_se)) __add_rq_bw(dl_se->dl_bw, dl_rq); } static inline void sub_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) { if (!dl_entity_is_special(dl_se)) __sub_rq_bw(dl_se->dl_bw, dl_rq); } static inline void add_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) { if (!dl_entity_is_special(dl_se)) __add_running_bw(dl_se->dl_bw, dl_rq); } static inline void sub_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) { if (!dl_entity_is_special(dl_se)) __sub_running_bw(dl_se->dl_bw, dl_rq); } void dl_change_utilization(struct task_struct *p, u64 new_bw) { struct rq *rq; BUG_ON(p->dl.flags & SCHED_FLAG_SUGOV); if (task_on_rq_queued(p)) return; rq = task_rq(p); if (p->dl.dl_non_contending) { sub_running_bw(&p->dl, &rq->dl); p->dl.dl_non_contending = 0; /* * If the timer handler is currently running and the * timer cannot be cancelled, inactive_task_timer() * will see that dl_not_contending is not set, and * will not touch the rq's active utilization, * so we are still safe. */ if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) put_task_struct(p); } __sub_rq_bw(p->dl.dl_bw, &rq->dl); __add_rq_bw(new_bw, &rq->dl); } /* * The utilization of a task cannot be immediately removed from * the rq active utilization (running_bw) when the task blocks. * Instead, we have to wait for the so called "0-lag time". * * If a task blocks before the "0-lag time", a timer (the inactive * timer) is armed, and running_bw is decreased when the timer * fires. * * If the task wakes up again before the inactive timer fires, * the timer is cancelled, whereas if the task wakes up after the * inactive timer fired (and running_bw has been decreased) the * task's utilization has to be added to running_bw again. * A flag in the deadline scheduling entity (dl_non_contending) * is used to avoid race conditions between the inactive timer handler * and task wakeups. * * The following diagram shows how running_bw is updated. A task is * "ACTIVE" when its utilization contributes to running_bw; an * "ACTIVE contending" task is in the TASK_RUNNING state, while an * "ACTIVE non contending" task is a blocked task for which the "0-lag time" * has not passed yet. An "INACTIVE" task is a task for which the "0-lag" * time already passed, which does not contribute to running_bw anymore. * +------------------+ * wakeup | ACTIVE | * +------------------>+ contending | * | add_running_bw | | * | +----+------+------+ * | | ^ * | dequeue | | * +--------+-------+ | | * | | t >= 0-lag | | wakeup * | INACTIVE |<---------------+ | * | | sub_running_bw | | * +--------+-------+ | | * ^ | | * | t < 0-lag | | * | | | * | V | * | +----+------+------+ * | sub_running_bw | ACTIVE | * +-------------------+ | * inactive timer | non contending | * fired +------------------+ * * The task_non_contending() function is invoked when a task * blocks, and checks if the 0-lag time already passed or * not (in the first case, it directly updates running_bw; * in the second case, it arms the inactive timer). * * The task_contending() function is invoked when a task wakes * 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) { 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); s64 zerolag_time; /* * If this is a non-deadline task that has been boosted, * do nothing */ if (dl_se->dl_runtime == 0) return; if (dl_entity_is_special(dl_se)) return; WARN_ON(hrtimer_active(&dl_se->inactive_timer)); WARN_ON(dl_se->dl_non_contending); zerolag_time = dl_se->deadline - div64_long((dl_se->runtime * dl_se->dl_period), dl_se->dl_runtime); /* * Using relative times instead of the absolute "0-lag time" * allows to simplify the code */ zerolag_time -= rq_clock(rq); /* * If the "0-lag time" already passed, decrease the active * utilization now, instead of starting a timer */ if (zerolag_time < 0) { if (dl_task(p)) sub_running_bw(dl_se, dl_rq); if (!dl_task(p) || p->state == TASK_DEAD) { struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); if (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))); __dl_clear_params(p); raw_spin_unlock(&dl_b->lock); } return; } dl_se->dl_non_contending = 1; get_task_struct(p); hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL); } static void task_contending(struct sched_dl_entity *dl_se, int flags) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); /* * If this is a non-deadline task that has been boosted, * do nothing */ if (dl_se->dl_runtime == 0) return; if (flags & ENQUEUE_MIGRATED) add_rq_bw(dl_se, dl_rq); if (dl_se->dl_non_contending) { dl_se->dl_non_contending = 0; /* * If the timer handler is currently running and the * timer cannot be cancelled, inactive_task_timer() * will see that dl_not_contending is not set, and * 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)); } else { /* * Since "dl_non_contending" is not set, the * task's utilization has already been removed from * active utilization (either when the task blocked, * when the "inactive timer" fired). * So, add it back. */ add_running_bw(dl_se, dl_rq); } } 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->root.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; } 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) { dl_rq->root = RB_ROOT_CACHED; #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_CACHED; #else init_dl_bw(&dl_rq->dl_bw); #endif dl_rq->running_bw = 0; dl_rq->this_bw = 0; init_dl_rq_bw_ratio(dl_rq); } #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_root.rb_node; struct rb_node *parent = NULL; struct task_struct *entry; bool leftmost = true; 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 = false; } } if (leftmost) dl_rq->earliest_dl.next = p->dl.deadline; rb_link_node(&p->pushable_dl_tasks, parent, link); rb_insert_color_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root, leftmost); } 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_root.rb_leftmost == &p->pushable_dl_tasks) { struct rb_node *next_node; next_node = rb_next(&p->pushable_dl_tasks); if (next_node) { dl_rq->earliest_dl.next = rb_entry(next_node, struct task_struct, pushable_dl_tasks)->dl.deadline; } } rb_erase_cached(&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.rb_root); } static int push_dl_task(struct rq *rq); static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) { return dl_task(prev); } static DEFINE_PER_CPU(struct callback_head, dl_push_head); static DEFINE_PER_CPU(struct callback_head, dl_pull_head); static void push_dl_tasks(struct rq *); static void pull_dl_task(struct rq *); static inline void deadline_queue_push_tasks(struct rq *rq) { if (!has_pushable_dl_tasks(rq)) return; queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks); } static inline void deadline_queue_pull_task(struct rq *rq) { queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task); } static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq); static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p) { struct rq *later_rq = NULL; later_rq = find_lock_later_rq(p, rq); if (!later_rq) { int cpu; /* * If we cannot preempt any rq, fall back to pick any * online CPU: */ cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed); if (cpu >= nr_cpu_ids) { /* * Failed to find any suitable CPU. * The task will never come back! */ BUG_ON(dl_bandwidth_enabled()); /* * If admission control is disabled we * try a little harder to let the task * run. */ cpu = cpumask_any(cpu_active_mask); } later_rq = cpu_rq(cpu); double_lock_balance(rq, later_rq); } set_task_cpu(p, later_rq->cpu); double_unlock_balance(later_rq, rq); return later_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) { } static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) { return false; } static inline void pull_dl_task(struct rq *rq) { } static inline void deadline_queue_push_tasks(struct rq *rq) { } static inline void deadline_queue_pull_task(struct rq *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 dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq); WARN_ON(dl_se->dl_boosted); WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline)); /* * We are racing with the deadline timer. So, do nothing because * the deadline timer handler will take care of properly recharging * the runtime and postponing the deadline */ if (dl_se->dl_throttled) return; /* * 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) + dl_se->dl_deadline; dl_se->runtime = dl_se->dl_runtime; } /* * 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_setattr(). */ 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; } if (dl_se->dl_yielded && dl_se->runtime > 0) dl_se->runtime = 0; /* * 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))) { printk_deferred_once("sched: DL replenish lagged too much\n"); dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; dl_se->runtime = pi_se->dl_runtime; } if (dl_se->dl_yielded) dl_se->dl_yielded = 0; if (dl_se->dl_throttled) dl_se->dl_throttled = 0; } /* * 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_deadline , * * IOW we can't recycle current parameters. * * Notice that the bandwidth check is done against the deadline. For * task with deadline equal to period this is the same of using * dl_period instead of dl_deadline 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_deadline >> 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); } /* * Revised wakeup rule [1]: For self-suspending tasks, rather then * re-initializing task's runtime and deadline, the revised wakeup * rule adjusts the task's runtime to avoid the task to overrun its * density. * * Reasoning: a task may overrun the density if: * runtime / (deadline - t) > dl_runtime / dl_deadline * * Therefore, runtime can be adjusted to: * runtime = (dl_runtime / dl_deadline) * (deadline - t) * * In such way that runtime will be equal to the maximum density * the task can use without breaking any rule. * * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24. */ static void update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq) { u64 laxity = dl_se->deadline - rq_clock(rq); /* * If the task has deadline < period, and the deadline is in the past, * it should already be throttled before this check. * * See update_dl_entity() comments for further details. */ WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq))); dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT; } /* * Regarding the deadline, a task with implicit deadline has a relative * deadline == relative period. A task with constrained deadline has a * relative deadline <= relative period. * * We support constrained deadline tasks. However, there are some restrictions * applied only for tasks which do not have an implicit deadline. See * update_dl_entity() to know more about such restrictions. * * The dl_is_implicit() returns true if the task has an implicit deadline. */ static inline bool dl_is_implicit(struct sched_dl_entity *dl_se) { return dl_se->dl_deadline == dl_se->dl_period; } /* * When a deadline entity is placed in the runqueue, its runtime and deadline * might need to be updated. This is done by a CBS wake up rule. There are two * different rules: 1) the original CBS; and 2) the Revisited CBS. * * When the task is starting a new period, the Original CBS is used. In this * case, the runtime is replenished and a new absolute deadline is set. * * When a task is queued before the begin of the next period, using the * remaining runtime and deadline could make the entity to overflow, see * dl_entity_overflow() to find more about runtime overflow. When such case * is detected, the runtime and deadline need to be updated. * * If the task has an implicit deadline, i.e., deadline == period, the Original * CBS is applied. the runtime is replenished and a new absolute deadline is * set, as in the previous cases. * * However, the Original CBS does not work properly for tasks with * deadline < period, which are said to have a constrained deadline. By * applying the Original CBS, a constrained deadline task would be able to run * runtime/deadline in a period. With deadline < period, the task would * overrun the runtime/period allowed bandwidth, breaking the admission test. * * In order to prevent this misbehave, the Revisited CBS is used for * constrained deadline tasks when a runtime overflow is detected. In the * Revisited CBS, rather than replenishing & setting a new absolute deadline, * the remaining runtime of the task is reduced to avoid runtime overflow. * Please refer to the comments update_dl_revised_wakeup() function to find * more about the Revised CBS rule. */ 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); if (dl_time_before(dl_se->deadline, rq_clock(rq)) || dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { if (unlikely(!dl_is_implicit(dl_se) && !dl_time_before(dl_se->deadline, rq_clock(rq)) && !dl_se->dl_boosted)){ update_dl_revised_wakeup(dl_se, rq); return; } dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; dl_se->runtime = pi_se->dl_runtime; } } static inline u64 dl_next_period(struct sched_dl_entity *dl_se) { return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period; } /* * 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 replenishment 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 task_struct *p) { struct sched_dl_entity *dl_se = &p->dl; struct hrtimer *timer = &dl_se->dl_timer; struct rq *rq = task_rq(p); ktime_t now, act; s64 delta; lockdep_assert_held(&rq->lock); /* * 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_next_period(dl_se)); now = hrtimer_cb_get_time(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; /* * !enqueued will guarantee another callback; even if one is already in * progress. This ensures a balanced {get,put}_task_struct(). * * The race against __run_timer() clearing the enqueued state is * harmless because we're holding task_rq()->lock, therefore the timer * expiring after we've done the check will wait on its task_rq_lock() * and observe our state. */ if (!hrtimer_is_queued(timer)) { get_task_struct(p); hrtimer_start(timer, act, HRTIMER_MODE_ABS); } return 1; } /* * 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_flags rf; struct rq *rq; rq = task_rq_lock(p, &rf); /* * The task might have changed its scheduling policy to something * different than SCHED_DEADLINE (through switched_from_dl()). */ if (!dl_task(p)) goto unlock; /* * The task might have been boosted by someone else and might be in the * boosting/deboosting path, its not throttled. */ if (dl_se->dl_boosted) goto unlock; /* * Spurious timer due to start_dl_timer() race; or we already received * a replenishment from rt_mutex_setprio(). */ if (!dl_se->dl_throttled) goto unlock; sched_clock_tick(); update_rq_clock(rq); /* * If the throttle happened during sched-out; like: * * schedule() * deactivate_task() * dequeue_task_dl() * update_curr_dl() * start_dl_timer() * __dequeue_task_dl() * prev->on_rq = 0; * * We can be both throttled and !queued. Replenish the counter * but do not enqueue -- wait for our wakeup to do that. */ if (!task_on_rq_queued(p)) { replenish_dl_entity(dl_se, dl_se); goto unlock; } #ifdef CONFIG_SMP if (unlikely(!rq->online)) { /* * If the runqueue is no longer available, migrate the * task elsewhere. This necessarily changes rq. */ lockdep_unpin_lock(&rq->lock, rf.cookie); rq = dl_task_offline_migration(rq, p); rf.cookie = lockdep_pin_lock(&rq->lock); update_rq_clock(rq); /* * Now that the task has been migrated to the new RQ and we * have that locked, proceed as normal and enqueue the task * there. */ } #endif enqueue_task_dl(rq, p, ENQUEUE_REPLENISH); if (dl_task(rq->curr)) check_preempt_curr_dl(rq, p, 0); 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 unlock: task_rq_unlock(rq, p, &rf); /* * This can free the task_struct, including this hrtimer, do not touch * anything related to that after this. */ put_task_struct(p); return HRTIMER_NORESTART; } void init_dl_task_timer(struct sched_dl_entity *dl_se) { struct hrtimer *timer = &dl_se->dl_timer; hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); timer->function = dl_task_timer; } /* * During the activation, CBS checks if it can reuse the current task's * runtime and period. If the deadline of the task is in the past, CBS * cannot use the runtime, and so it replenishes the task. This rule * works fine for implicit deadline tasks (deadline == period), and the * CBS was designed for implicit deadline tasks. However, a task with * constrained deadline (deadine < period) might be awakened after the * deadline, but before the next period. In this case, replenishing the * task would allow it to run for runtime / deadline. As in this case * deadline < period, CBS enables a task to run for more than the * runtime / period. In a very loaded system, this can cause a domino * effect, making other tasks miss their deadlines. * * To avoid this problem, in the activation of a constrained deadline * task after the deadline but before the next period, throttle the * task and set the replenishing timer to the begin of the next period, * unless it is boosted. */ 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)); if (dl_time_before(dl_se->deadline, rq_clock(rq)) && dl_time_before(rq_clock(rq), dl_next_period(dl_se))) { if (unlikely(dl_se->dl_boosted || !start_dl_timer(p))) return; dl_se->dl_throttled = 1; if (dl_se->runtime > 0) dl_se->runtime = 0; } } static int dl_runtime_exceeded(struct sched_dl_entity *dl_se) { return (dl_se->runtime <= 0); } extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq); /* * This function implements the GRUB accounting rule: * according to the GRUB reclaiming algorithm, the runtime is * not decreased as "dq = -dt", but as * "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt", * where u is the utilization of the task, Umax is the maximum reclaimable * utilization, Uinact is the (per-runqueue) inactive utilization, computed * as the difference between the "total runqueue utilization" and the * runqueue active utilization, and Uextra is the (per runqueue) extra * reclaimable utilization. * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations * multiplied by 2^BW_SHIFT, the result has to be shifted right by * BW_SHIFT. * Since rq->dl.bw_ratio contains 1 / Umax multipled by 2^RATIO_SHIFT, * dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT. * Since delta is a 64 bit variable, to have an overflow its value * should be larger than 2^(64 - 20 - 8), which is more than 64 seconds. * So, overflow is not an issue here. */ static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se) { u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */ u64 u_act; u64 u_act_min = (dl_se->dl_bw * rq->dl.bw_ratio) >> RATIO_SHIFT; /* * Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)}, * we compare u_inact + rq->dl.extra_bw with * 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because * u_inact + rq->dl.extra_bw can be larger than * 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative * leading to wrong results) */ if (u_inact + rq->dl.extra_bw > BW_UNIT - u_act_min) u_act = u_act_min; else u_act = BW_UNIT - u_inact - rq->dl.extra_bw; 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) { 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; /* * 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(dl_se->dl_yielded)) goto throttle; return; } 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 = now; cgroup_account_cputime(curr, delta_exec); if (dl_entity_is_special(dl_se)) return; /* * For tasks that participate in GRUB, we implement GRUB-PA: the * spare reclaimed bandwidth is used to clock down frequency. * * For the others, we still need to scale reservation parameters * 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); } else { unsigned long scale_freq = arch_scale_freq_capacity(cpu); unsigned long scale_cpu = arch_scale_cpu_capacity(NULL, cpu); scaled_delta_exec = cap_scale(delta_exec, scale_freq); scaled_delta_exec = cap_scale(scaled_delta_exec, scale_cpu); } dl_se->runtime -= scaled_delta_exec; throttle: if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) { dl_se->dl_throttled = 1; /* If requested, inform the user about runtime overruns. */ if (dl_runtime_exceeded(dl_se) && (dl_se->flags & SCHED_FLAG_DL_OVERRUN)) dl_se->dl_overrun = 1; __dequeue_task_dl(rq, curr, 0); if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr))) enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH); if (!is_leftmost(curr, &rq->dl)) resched_curr(rq); } /* * 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); } } 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 rq_flags rf; struct rq *rq; rq = task_rq_lock(p, &rf); sched_clock_tick(); update_rq_clock(rq); if (!dl_task(p) || p->state == TASK_DEAD) { struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); if (p->state == TASK_DEAD && dl_se->dl_non_contending) { sub_running_bw(&p->dl, dl_rq_of_se(&p->dl)); sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl)); dl_se->dl_non_contending = 0; } 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); goto unlock; } 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); return HRTIMER_NORESTART; } void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se) { struct hrtimer *timer = &dl_se->inactive_timer; hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); timer->function = inactive_task_timer; } #ifdef CONFIG_SMP 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)) { dl_rq->earliest_dl.curr = deadline; cpudl_set(&rq->rd->cpudl, rq->cpu, deadline); } } 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_clear(&rq->rd->cpudl, rq->cpu); } else { struct rb_node *leftmost = dl_rq->root.rb_leftmost; struct sched_dl_entity *entry; entry = rb_entry(leftmost, struct sched_dl_entity, rb_node); dl_rq->earliest_dl.curr = entry->deadline; cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline); } } #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++; add_nr_running(rq_of_dl_rq(dl_rq), 1); 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--; sub_nr_running(rq_of_dl_rq(dl_rq), 1); 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->root.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; } } rb_link_node(&dl_se->rb_node, parent, link); rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost); 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; rb_erase_cached(&dl_se->rb_node, &dl_rq->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 (flags & ENQUEUE_WAKEUP) { task_contending(dl_se, flags); update_dl_entity(dl_se, pi_se); } else if (flags & ENQUEUE_REPLENISH) { replenish_dl_entity(dl_se, pi_se); } else if ((flags & ENQUEUE_RESTORE) && dl_time_before(dl_se->deadline, rq_clock(rq_of_dl_rq(dl_rq_of_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) { __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 a top pi-waiter which is a SCHED_DEADLINE task AND * - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is * smaller than our deadline OR we are a !SCHED_DEADLINE task getting * boosted due to a SCHED_DEADLINE pi-waiter). * Otherwise we keep our runtime and deadline. */ if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) { pi_se = &pi_task->dl; } else if (!dl_prio(p->normal_prio)) { /* * Special case in which we have a !SCHED_DEADLINE task * that is going to be deboosted, but exceeds its * runtime while doing so. No point in replenishing * it, as it's going to return back to its original * scheduling class after this. */ BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); 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; } 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); 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); } /* * 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); } /* * 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) { /* * 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_yielded=1). */ rq->curr->dl.dl_yielded = 1; update_rq_clock(rq); update_curr_dl(rq); /* * Tell update_rq_clock() that we've just updated, * so we don't do microscopic update in schedule() * and double the fastpath cost. */ rq_clock_skip_update(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) goto out; rq = cpu_rq(cpu); rcu_read_lock(); curr = READ_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 && (dl_time_before(p->dl.deadline, cpu_rq(target)->dl.earliest_dl.curr) || (cpu_rq(target)->dl.dl_nr_running == 0))) cpu = target; } rcu_read_unlock(); out: return cpu; } static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused) { struct rq *rq; if (p->state != TASK_WAKING) return; rq = task_rq(p); /* * Since p->state == TASK_WAKING, set_task_cpu() has been called * from try_to_wake_up(). Hence, p->pi_lock is locked, but * rq->lock is not... So, lock it */ raw_spin_lock(&rq->lock); if (p->dl.dl_non_contending) { sub_running_bw(&p->dl, &rq->dl); p->dl.dl_non_contending = 0; /* * If the timer handler is currently running and the * timer cannot be cancelled, inactive_task_timer() * will see that dl_not_contending is not set, and * will not touch the rq's active utilization, * so we are still safe. */ if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) put_task_struct(p); } sub_rq_bw(&p->dl, &rq->dl); raw_spin_unlock(&rq->lock); } 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)) 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)) return; resched_curr(rq); } #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_curr(rq); 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) { hrtick_start(rq, p->dl.runtime); } #else /* !CONFIG_SCHED_HRTICK */ static void start_hrtick_dl(struct rq *rq, struct task_struct *p) { } #endif static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, struct dl_rq *dl_rq) { struct rb_node *left = rb_first_cached(&dl_rq->root); if (!left) return NULL; return rb_entry(left, struct sched_dl_entity, rb_node); } static struct task_struct * pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { struct sched_dl_entity *dl_se; struct task_struct *p; struct dl_rq *dl_rq; dl_rq = &rq->dl; if (need_pull_dl_task(rq, prev)) { /* * This is OK, because current is on_cpu, which avoids it being * picked for load-balance and preemption/IRQs are still * disabled avoiding further scheduler activity on it and we're * being very careful to re-start the picking loop. */ rq_unpin_lock(rq, rf); pull_dl_task(rq); rq_repin_lock(rq, rf); /* * pull_dl_task() can drop (and re-acquire) rq->lock; this * means a stop task can slip in, in which case we need to * re-start task selection. */ if (rq->stop && task_on_rq_queued(rq->stop)) return RETRY_TASK; } /* * When prev is DL, we may throttle it in put_prev_task(). * So, we update time before we check for dl_nr_running. */ if (prev->sched_class == &dl_sched_class) update_curr_dl(rq); if (unlikely(!dl_rq->dl_nr_running)) return NULL; put_prev_task(rq, prev); 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); if (hrtick_enabled(rq)) start_hrtick_dl(rq, p); deadline_queue_push_tasks(rq); if (rq->curr->sched_class != &dl_sched_class) update_dl_rq_load_avg(rq_clock_task(rq), rq, 0); return p; } static void put_prev_task_dl(struct rq *rq, struct task_struct *p) { update_curr_dl(rq); update_dl_rq_load_avg(rq_clock_task(rq), rq, 1); if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1) enqueue_pushable_dl_task(rq, p); } /* * scheduler tick hitting a task of our scheduling class. * * NOTE: This function can be called remotely by the tick offload that * goes along full dynticks. Therefore no local assumption can be made * and everything must be accessed through the @rq and @curr passed in * parameters. */ static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued) { update_curr_dl(rq); update_dl_rq_load_avg(rq_clock_task(rq), rq, 1); /* * Even when we have runtime, update_curr_dl() might have resulted in us * not being the leftmost task anymore. In that case NEED_RESCHED will * be set and schedule() will start a new hrtick for the next task. */ if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 && is_leftmost(p, &rq->dl)) start_hrtick_dl(rq, p); } static void task_fork_dl(struct task_struct *p) { /* * SCHED_DEADLINE tasks cannot fork and this is achieved through * sched_fork() */ } 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) && cpumask_test_cpu(cpu, &p->cpus_allowed)) return 1; return 0; } /* * Return the earliest pushable rq's task, which is suitable to be executed * on the CPU, NULL otherwise: */ static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu) { struct rb_node *next_node = rq->dl.pushable_dl_tasks_root.rb_leftmost; struct task_struct *p = NULL; if (!has_pushable_dl_tasks(rq)) return NULL; next_node: if (next_node) { p = rb_entry(next_node, struct task_struct, pushable_dl_tasks); if (pick_dl_task(rq, p, cpu)) return p; next_node = rb_next(next_node); 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 = this_cpu_cpumask_var_ptr(local_cpu_mask_dl); int this_cpu = smp_processor_id(); int 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; /* * We have to consider system topology and task affinity * first, then we can look for a suitable CPU. */ if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask)) return -1; /* * If we are here, some targets have been found, including * the most suitable which 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) { int best_cpu; /* * 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; } best_cpu = cpumask_first_and(later_mask, sched_domain_span(sd)); /* * Last chance: if a CPU being in both later_mask * and current sd span is valid, that becomes our * choice. Of course, the latest possible CPU is * already under consideration through later_mask. */ if (best_cpu < nr_cpu_ids) { 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); if (later_rq->dl.dl_nr_running && !dl_time_before(task->dl.deadline, later_rq->dl.earliest_dl.curr)) { /* * Target rq has tasks of equal or earlier deadline, * retrying does not release any lock and is unlikely * to yield a different result. */ later_rq = NULL; break; } /* 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) || !dl_task(task) || !task_on_rq_queued(task))) { 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_root.rb_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(!task_on_rq_queued(p)); 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; int ret = 0; 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_curr(rq); 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 == next_task) { /* * The task is still there. We don't try * again, some other CPU will pull it when ready. */ 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); sub_running_bw(&next_task->dl, &rq->dl); sub_rq_bw(&next_task->dl, &rq->dl); set_task_cpu(next_task, later_rq->cpu); add_rq_bw(&next_task->dl, &later_rq->dl); /* * Update the later_rq clock here, because the clock is used * by the cpufreq_update_util() inside __add_running_bw(). */ update_rq_clock(later_rq); add_running_bw(&next_task->dl, &later_rq->dl); activate_task(later_rq, next_task, ENQUEUE_NOCLOCK); ret = 1; resched_curr(later_rq); double_unlock_balance(rq, later_rq); out: put_task_struct(next_task); return ret; } static void push_dl_tasks(struct rq *rq) { /* push_dl_task() will return true if it moved a -deadline task */ while (push_dl_task(rq)) ; } static void pull_dl_task(struct rq *this_rq) { int this_cpu = this_rq->cpu, cpu; struct task_struct *p; bool resched = false; struct rq *src_rq; u64 dmin = LONG_MAX; if (likely(!dl_overloaded(this_rq))) return; /* * 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_earliest_pushable_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(!task_on_rq_queued(p)); /* * 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; resched = true; deactivate_task(src_rq, p, 0); sub_running_bw(&p->dl, &src_rq->dl); sub_rq_bw(&p->dl, &src_rq->dl); set_task_cpu(p, this_cpu); add_rq_bw(&p->dl, &this_rq->dl); add_running_bw(&p->dl, &this_rq->dl); 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); } if (resched) resched_curr(this_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) && p->nr_cpus_allowed > 1 && dl_task(rq->curr) && (rq->curr->nr_cpus_allowed < 2 || !dl_entity_preempt(&p->dl, &rq->curr->dl))) { push_dl_tasks(rq); } } static void set_cpus_allowed_dl(struct task_struct *p, const struct cpumask *new_mask) { struct root_domain *src_rd; struct rq *rq; BUG_ON(!dl_task(p)); rq = task_rq(p); src_rd = rq->rd; /* * Migrating a SCHED_DEADLINE task between exclusive * cpusets (different root_domains) entails a bandwidth * update. We already made space for us in the destination * domain (see cpuset_can_attach()). */ if (!cpumask_intersects(src_rd->span, new_mask)) { struct dl_bw *src_dl_b; src_dl_b = dl_bw_of(cpu_of(rq)); /* * We now free resources of the root_domain we are migrating * off. In the worst case, sched_setattr() may temporary fail * until we complete the update. */ raw_spin_lock(&src_dl_b->lock); __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); raw_spin_unlock(&src_dl_b->lock); } set_cpus_allowed_common(p, new_mask); } /* Assumes rq->lock is held */ static void rq_online_dl(struct rq *rq) { if (rq->dl.overloaded) dl_set_overload(rq); cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu); if (rq->dl.dl_nr_running > 0) cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr); } /* Assumes rq->lock is held */ static void rq_offline_dl(struct rq *rq) { if (rq->dl.overloaded) dl_clear_overload(rq); cpudl_clear(&rq->rd->cpudl, rq->cpu); cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); } void __init 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) { /* * task_non_contending() can start the "inactive timer" (if the 0-lag * time is in the future). If the task switches back to dl before * the "inactive timer" fires, it can continue to consume its current * runtime using its current deadline. If it stays outside of * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer() * will reset the task parameters. */ if (task_on_rq_queued(p) && p->dl.dl_runtime) task_non_contending(p); if (!task_on_rq_queued(p)) { /* * Inactive timer is armed. However, p is leaving DEADLINE and * might migrate away from this rq while continuing to run on * some other class. We need to remove its contribution from * this rq running_bw now, or sub_rq_bw (below) will complain. */ if (p->dl.dl_non_contending) sub_running_bw(&p->dl, &rq->dl); sub_rq_bw(&p->dl, &rq->dl); } /* * We cannot use inactive_task_timer() to invoke sub_running_bw() * at the 0-lag time, because the task could have been migrated * while SCHED_OTHER in the meanwhile. */ if (p->dl.dl_non_contending) p->dl.dl_non_contending = 0; /* * 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 (!task_on_rq_queued(p) || rq->dl.dl_nr_running) return; deadline_queue_pull_task(rq); } /* * 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) { if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) put_task_struct(p); /* If p is not queued we will update its parameters at next wakeup. */ if (!task_on_rq_queued(p)) { add_rq_bw(&p->dl, &rq->dl); return; } if (rq->curr != p) { #ifdef CONFIG_SMP if (p->nr_cpus_allowed > 1 && rq->dl.overloaded) deadline_queue_push_tasks(rq); #endif if (dl_task(rq->curr)) check_preempt_curr_dl(rq, p, 0); else resched_curr(rq); } } /* * 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 (task_on_rq_queued(p) || 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) deadline_queue_pull_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)) resched_curr(rq); #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_curr(rq); #endif /* CONFIG_SMP */ } } 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, .migrate_task_rq = migrate_task_rq_dl, .set_cpus_allowed = set_cpus_allowed_dl, .rq_online = rq_online_dl, .rq_offline = rq_offline_dl, .task_woken = task_woken_dl, #endif .set_curr_task = set_curr_task_dl, .task_tick = task_tick_dl, .task_fork = task_fork_dl, .prio_changed = prio_changed_dl, .switched_from = switched_from_dl, .switched_to = switched_to_dl, .update_curr = update_curr_dl, }; int sched_dl_global_validate(void) { u64 runtime = global_rt_runtime(); u64 period = global_rt_period(); u64 new_bw = to_ratio(period, runtime); struct dl_bw *dl_b; int cpu, ret = 0; unsigned long flags; /* * Here we want to check the bandwidth not being set to some * value smaller than the currently allocated bandwidth in * any of the root_domains. * * FIXME: Cycling on all the CPUs is overdoing, but simpler than * cycling on root_domains... Discussion on different/better * solutions is welcome! */ for_each_possible_cpu(cpu) { rcu_read_lock_sched(); dl_b = dl_bw_of(cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); if (new_bw < dl_b->total_bw) ret = -EBUSY; raw_spin_unlock_irqrestore(&dl_b->lock, flags); rcu_read_unlock_sched(); if (ret) break; } return ret; } void init_dl_rq_bw_ratio(struct dl_rq *dl_rq) { if (global_rt_runtime() == RUNTIME_INF) { dl_rq->bw_ratio = 1 << RATIO_SHIFT; dl_rq->extra_bw = 1 << BW_SHIFT; } else { dl_rq->bw_ratio = to_ratio(global_rt_runtime(), global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT); dl_rq->extra_bw = to_ratio(global_rt_period(), global_rt_runtime()); } } void sched_dl_do_global(void) { u64 new_bw = -1; struct dl_bw *dl_b; int cpu; unsigned long flags; def_dl_bandwidth.dl_period = global_rt_period(); def_dl_bandwidth.dl_runtime = global_rt_runtime(); if (global_rt_runtime() != RUNTIME_INF) new_bw = to_ratio(global_rt_period(), global_rt_runtime()); /* * FIXME: As above... */ for_each_possible_cpu(cpu) { rcu_read_lock_sched(); dl_b = dl_bw_of(cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); dl_b->bw = new_bw; raw_spin_unlock_irqrestore(&dl_b->lock, flags); rcu_read_unlock_sched(); init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl); } } /* * We must be sure that accepting a new task (or allowing changing the * parameters of an existing one) is consistent with the bandwidth * constraints. If yes, this function also accordingly updates the currently * allocated bandwidth to reflect the new situation. * * This function is called while holding p's rq->lock. */ int sched_dl_overflow(struct task_struct *p, int policy, const struct sched_attr *attr) { struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); u64 period = attr->sched_period ?: attr->sched_deadline; u64 runtime = attr->sched_runtime; u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0; int cpus, err = -1; if (attr->sched_flags & SCHED_FLAG_SUGOV) return 0; /* !deadline task may carry old deadline bandwidth */ if (new_bw == p->dl.dl_bw && task_has_dl_policy(p)) return 0; /* * Either if a task, enters, leave, or stays -deadline but changes * its parameters, we may need to update accordingly the total * allocated bandwidth of the container. */ raw_spin_lock(&dl_b->lock); cpus = dl_bw_cpus(task_cpu(p)); if (dl_policy(policy) && !task_has_dl_policy(p) && !__dl_overflow(dl_b, cpus, 0, new_bw)) { if (hrtimer_active(&p->dl.inactive_timer)) __dl_sub(dl_b, p->dl.dl_bw, cpus); __dl_add(dl_b, new_bw, cpus); err = 0; } else if (dl_policy(policy) && task_has_dl_policy(p) && !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) { /* * XXX this is slightly incorrect: when the task * utilization decreases, we should delay the total * utilization change until the task's 0-lag point. * But this would require to set the task's "inactive * timer" when the task is not inactive. */ __dl_sub(dl_b, p->dl.dl_bw, cpus); __dl_add(dl_b, new_bw, cpus); dl_change_utilization(p, new_bw); err = 0; } else if (!dl_policy(policy) && task_has_dl_policy(p)) { /* * Do not decrease the total deadline utilization here, * switched_from_dl() will take care to do it at the correct * (0-lag) time. */ err = 0; } raw_spin_unlock(&dl_b->lock); return err; } /* * This function initializes the sched_dl_entity of a newly becoming * SCHED_DEADLINE task. * * Only the static values are considered here, the actual runtime and the * absolute deadline will be properly calculated when the task is enqueued * for the first time with its new policy. */ void __setparam_dl(struct task_struct *p, const struct sched_attr *attr) { struct sched_dl_entity *dl_se = &p->dl; dl_se->dl_runtime = attr->sched_runtime; dl_se->dl_deadline = attr->sched_deadline; dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline; dl_se->flags = attr->sched_flags; dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime); dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime); } void __getparam_dl(struct task_struct *p, struct sched_attr *attr) { struct sched_dl_entity *dl_se = &p->dl; attr->sched_priority = p->rt_priority; attr->sched_runtime = dl_se->dl_runtime; attr->sched_deadline = dl_se->dl_deadline; attr->sched_period = dl_se->dl_period; attr->sched_flags = dl_se->flags; } /* * This function validates the new parameters of a -deadline task. * We ask for the deadline not being zero, and greater or equal * than the runtime, as well as the period of being zero or * greater than deadline. Furthermore, we have to be sure that * user parameters are above the internal resolution of 1us (we * check sched_runtime only since it is always the smaller one) and * below 2^63 ns (we have to check both sched_deadline and * sched_period, as the latter can be zero). */ bool __checkparam_dl(const struct sched_attr *attr) { /* special dl tasks don't actually use any parameter */ if (attr->sched_flags & SCHED_FLAG_SUGOV) return true; /* deadline != 0 */ if (attr->sched_deadline == 0) return false; /* * Since we truncate DL_SCALE bits, make sure we're at least * that big. */ if (attr->sched_runtime < (1ULL << DL_SCALE)) return false; /* * Since we use the MSB for wrap-around and sign issues, make * sure it's not set (mind that period can be equal to zero). */ if (attr->sched_deadline & (1ULL << 63) || attr->sched_period & (1ULL << 63)) return false; /* runtime <= deadline <= period (if period != 0) */ if ((attr->sched_period != 0 && attr->sched_period < attr->sched_deadline) || attr->sched_deadline < attr->sched_runtime) return false; return true; } /* * This function clears the sched_dl_entity static params. */ void __dl_clear_params(struct task_struct *p) { struct sched_dl_entity *dl_se = &p->dl; dl_se->dl_runtime = 0; dl_se->dl_deadline = 0; dl_se->dl_period = 0; dl_se->flags = 0; dl_se->dl_bw = 0; dl_se->dl_density = 0; dl_se->dl_throttled = 0; dl_se->dl_yielded = 0; dl_se->dl_non_contending = 0; dl_se->dl_overrun = 0; } bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr) { struct sched_dl_entity *dl_se = &p->dl; if (dl_se->dl_runtime != attr->sched_runtime || dl_se->dl_deadline != attr->sched_deadline || dl_se->dl_period != attr->sched_period || dl_se->flags != attr->sched_flags) return true; return false; } #ifdef CONFIG_SMP int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed) { unsigned int dest_cpu; struct dl_bw *dl_b; bool overflow; int cpus, ret; unsigned long flags; dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed); rcu_read_lock_sched(); dl_b = dl_bw_of(dest_cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); cpus = dl_bw_cpus(dest_cpu); overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw); if (overflow) { ret = -EBUSY; } else { /* * We reserve space for this task in the destination * root_domain, as we can't fail after this point. * We will free resources in the source root_domain * later on (see set_cpus_allowed_dl()). */ __dl_add(dl_b, p->dl.dl_bw, cpus); ret = 0; } raw_spin_unlock_irqrestore(&dl_b->lock, flags); rcu_read_unlock_sched(); return ret; } int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial) { int ret = 1, trial_cpus; struct dl_bw *cur_dl_b; unsigned long flags; rcu_read_lock_sched(); cur_dl_b = dl_bw_of(cpumask_any(cur)); trial_cpus = cpumask_weight(trial); raw_spin_lock_irqsave(&cur_dl_b->lock, flags); if (cur_dl_b->bw != -1 && cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw) ret = 0; raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags); rcu_read_unlock_sched(); return ret; } bool dl_cpu_busy(unsigned int cpu) { unsigned long flags; struct dl_bw *dl_b; bool overflow; int cpus; rcu_read_lock_sched(); dl_b = dl_bw_of(cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); cpus = dl_bw_cpus(cpu); overflow = __dl_overflow(dl_b, cpus, 0, 0); raw_spin_unlock_irqrestore(&dl_b->lock, flags); rcu_read_unlock_sched(); return overflow; } #endif #ifdef CONFIG_SCHED_DEBUG void print_dl_stats(struct seq_file *m, int cpu) { print_dl_rq(m, cpu, &cpu_rq(cpu)->dl); } #endif /* CONFIG_SCHED_DEBUG */
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