diff options
Diffstat (limited to 'kernel/sched/deadline.c')
| -rw-r--r-- | kernel/sched/deadline.c | 3787 |
1 files changed, 3787 insertions, 0 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c new file mode 100644 index 000000000000..319439fe1870 --- /dev/null +++ b/kernel/sched/deadline.c @@ -0,0 +1,3787 @@ +// 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 <linux/cpuset.h> +#include <linux/sched/clock.h> +#include <uapi/linux/sched/types.h> +#include "sched.h" +#include "pelt.h" + +/* + * Default limits for DL period; on the top end we guard against small util + * tasks still getting ridiculously long effective runtimes, on the bottom end we + * guard against timer DoS. + */ +static unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */ +static unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */ +#ifdef CONFIG_SYSCTL +static const struct ctl_table sched_dl_sysctls[] = { + { + .procname = "sched_deadline_period_max_us", + .data = &sysctl_sched_dl_period_max, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_douintvec_minmax, + .extra1 = (void *)&sysctl_sched_dl_period_min, + }, + { + .procname = "sched_deadline_period_min_us", + .data = &sysctl_sched_dl_period_min, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_douintvec_minmax, + .extra2 = (void *)&sysctl_sched_dl_period_max, + }, +}; + +static int __init sched_dl_sysctl_init(void) +{ + register_sysctl_init("kernel", sched_dl_sysctls); + return 0; +} +late_initcall(sched_dl_sysctl_init); +#endif /* CONFIG_SYSCTL */ + +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); +} + +static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq) +{ + return container_of(dl_rq, struct rq, dl); +} + +static inline struct rq *rq_of_dl_se(struct sched_dl_entity *dl_se) +{ + struct rq *rq = dl_se->rq; + + if (!dl_server(dl_se)) + rq = task_rq(dl_task_of(dl_se)); + + return rq; +} + +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) +{ + return !RB_EMPTY_NODE(&dl_se->rb_node); +} + +#ifdef CONFIG_RT_MUTEXES +static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se) +{ + return dl_se->pi_se; +} + +static inline bool is_dl_boosted(struct sched_dl_entity *dl_se) +{ + return pi_of(dl_se) != dl_se; +} +#else /* !CONFIG_RT_MUTEXES: */ +static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se) +{ + return dl_se; +} + +static inline bool is_dl_boosted(struct sched_dl_entity *dl_se) +{ + return false; +} +#endif /* !CONFIG_RT_MUTEXES */ + +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; + + RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), + "sched RCU must be held"); + + return cpumask_weight_and(rd->span, cpu_active_mask); +} + +static inline unsigned long __dl_bw_capacity(const struct cpumask *mask) +{ + unsigned long cap = 0; + int i; + + for_each_cpu_and(i, mask, cpu_active_mask) + cap += arch_scale_cpu_capacity(i); + + return cap; +} + +/* + * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity + * of the CPU the task is running on rather rd's \Sum CPU capacity. + */ +static inline unsigned long dl_bw_capacity(int i) +{ + if (!sched_asym_cpucap_active() && + arch_scale_cpu_capacity(i) == SCHED_CAPACITY_SCALE) { + return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT; + } else { + RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), + "sched RCU must be held"); + + return __dl_bw_capacity(cpu_rq(i)->rd->span); + } +} + +bool dl_bw_visited(int cpu, u64 cookie) +{ + struct root_domain *rd = cpu_rq(cpu)->rd; + + if (rd->visit_cookie == cookie) + return true; + + rd->visit_cookie = cookie; + return false; +} + +static inline +void __dl_update(struct dl_bw *dl_b, s64 bw) +{ + struct root_domain *rd = container_of(dl_b, struct root_domain, dl_bw); + int i; + + RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), + "sched RCU must be held"); + for_each_cpu_and(i, rd->span, cpu_active_mask) { + struct rq *rq = cpu_rq(i); + + rq->dl.extra_bw += bw; + } +} + +static inline +void __dl_sub(struct dl_bw *dl_b, u64 tsk_bw, int cpus) +{ + dl_b->total_bw -= tsk_bw; + __dl_update(dl_b, (s32)tsk_bw / cpus); +} + +static inline +void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus) +{ + dl_b->total_bw += tsk_bw; + __dl_update(dl_b, -((s32)tsk_bw / cpus)); +} + +static inline bool +__dl_overflow(struct dl_bw *dl_b, unsigned long cap, u64 old_bw, u64 new_bw) +{ + return dl_b->bw != -1 && + cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw; +} + +static inline +void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq) +{ + u64 old = dl_rq->running_bw; + + lockdep_assert_rq_held(rq_of_dl_rq(dl_rq)); + dl_rq->running_bw += dl_bw; + WARN_ON_ONCE(dl_rq->running_bw < old); /* overflow */ + WARN_ON_ONCE(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_rq_held(rq_of_dl_rq(dl_rq)); + dl_rq->running_bw -= dl_bw; + WARN_ON_ONCE(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_rq_held(rq_of_dl_rq(dl_rq)); + dl_rq->this_bw += dl_bw; + WARN_ON_ONCE(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_rq_held(rq_of_dl_rq(dl_rq)); + dl_rq->this_bw -= dl_bw; + WARN_ON_ONCE(dl_rq->this_bw > old); /* underflow */ + if (dl_rq->this_bw > old) + dl_rq->this_bw = 0; + WARN_ON_ONCE(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); +} + +static void dl_rq_change_utilization(struct rq *rq, struct sched_dl_entity *dl_se, u64 new_bw) +{ + if (dl_se->dl_non_contending) { + sub_running_bw(dl_se, &rq->dl); + dl_se->dl_non_contending = 0; + + /* + * If the timer handler is currently running and the + * timer cannot be canceled, 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) { + if (!dl_server(dl_se)) + put_task_struct(dl_task_of(dl_se)); + } + } + __sub_rq_bw(dl_se->dl_bw, &rq->dl); + __add_rq_bw(new_bw, &rq->dl); +} + +static __always_inline +void cancel_dl_timer(struct sched_dl_entity *dl_se, struct hrtimer *timer) +{ + /* + * If the timer callback was running (hrtimer_try_to_cancel == -1), + * it will eventually call put_task_struct(). + */ + if (hrtimer_try_to_cancel(timer) == 1 && !dl_server(dl_se)) + put_task_struct(dl_task_of(dl_se)); +} + +static __always_inline +void cancel_replenish_timer(struct sched_dl_entity *dl_se) +{ + cancel_dl_timer(dl_se, &dl_se->dl_timer); +} + +static __always_inline +void cancel_inactive_timer(struct sched_dl_entity *dl_se) +{ + cancel_dl_timer(dl_se, &dl_se->inactive_timer); +} + +static void dl_change_utilization(struct task_struct *p, u64 new_bw) +{ + WARN_ON_ONCE(p->dl.flags & SCHED_FLAG_SUGOV); + + if (task_on_rq_queued(p)) + return; + + dl_rq_change_utilization(task_rq(p), &p->dl, new_bw); +} + +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. + * 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 canceled, 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 sched_dl_entity *dl_se, bool dl_task) +{ + struct hrtimer *timer = &dl_se->inactive_timer; + struct rq *rq = rq_of_dl_se(dl_se); + struct dl_rq *dl_rq = &rq->dl; + 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(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) || hrtimer_active(&dl_se->inactive_timer)) { + if (dl_server(dl_se)) { + sub_running_bw(dl_se, dl_rq); + } else { + struct task_struct *p = dl_task_of(dl_se); + + if (dl_task) + sub_running_bw(dl_se, dl_rq); + + if (!dl_task || 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; + 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); +} + +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 canceled, 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. + */ + cancel_inactive_timer(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 sched_dl_entity *dl_se, struct dl_rq *dl_rq) +{ + return rb_first_cached(&dl_rq->root) == &dl_se->rb_node; +} + +static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq); + +void init_dl_bw(struct dl_bw *dl_b) +{ + raw_spin_lock_init(&dl_b->lock); + if (global_rt_runtime() == RUNTIME_INF) + dl_b->bw = -1; + else + dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime()); + dl_b->total_bw = 0; +} + +void init_dl_rq(struct dl_rq *dl_rq) +{ + dl_rq->root = RB_ROOT_CACHED; + + /* zero means no -deadline tasks */ + dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0; + + dl_rq->overloaded = 0; + dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED; + + dl_rq->running_bw = 0; + dl_rq->this_bw = 0; + init_dl_rq_bw_ratio(dl_rq); +} + +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); +} + +#define __node_2_pdl(node) \ + rb_entry((node), struct task_struct, pushable_dl_tasks) + +static inline bool __pushable_less(struct rb_node *a, const struct rb_node *b) +{ + return dl_entity_preempt(&__node_2_pdl(a)->dl, &__node_2_pdl(b)->dl); +} + +static inline int has_pushable_dl_tasks(struct rq *rq) +{ + return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root); +} + +/* + * 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 rb_node *leftmost; + + WARN_ON_ONCE(!RB_EMPTY_NODE(&p->pushable_dl_tasks)); + + leftmost = rb_add_cached(&p->pushable_dl_tasks, + &rq->dl.pushable_dl_tasks_root, + __pushable_less); + if (leftmost) + rq->dl.earliest_dl.next = p->dl.deadline; + + if (!rq->dl.overloaded) { + dl_set_overload(rq); + rq->dl.overloaded = 1; + } +} + +static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) +{ + struct dl_rq *dl_rq = &rq->dl; + struct rb_root_cached *root = &dl_rq->pushable_dl_tasks_root; + struct rb_node *leftmost; + + if (RB_EMPTY_NODE(&p->pushable_dl_tasks)) + return; + + leftmost = rb_erase_cached(&p->pushable_dl_tasks, root); + if (leftmost) + dl_rq->earliest_dl.next = __node_2_pdl(leftmost)->dl.deadline; + + RB_CLEAR_NODE(&p->pushable_dl_tasks); + + if (!has_pushable_dl_tasks(rq) && rq->dl.overloaded) { + dl_clear_overload(rq); + rq->dl.overloaded = 0; + } +} + +static int push_dl_task(struct rq *rq); + +static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) +{ + return rq->online && dl_task(prev); +} + +static DEFINE_PER_CPU(struct balance_callback, dl_push_head); +static DEFINE_PER_CPU(struct balance_callback, 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; + struct dl_bw *dl_b; + + 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_ptr); + if (cpu >= nr_cpu_ids) { + /* + * Failed to find any suitable CPU. + * The task will never come back! + */ + WARN_ON_ONCE(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); + } + + if (p->dl.dl_non_contending || p->dl.dl_throttled) { + /* + * Inactive timer is armed (or callback is running, but + * waiting for us to release rq locks). In any case, when it + * will fire (or continue), it will see running_bw of this + * task migrated to later_rq (and correctly handle it). + */ + sub_running_bw(&p->dl, &rq->dl); + sub_rq_bw(&p->dl, &rq->dl); + + add_rq_bw(&p->dl, &later_rq->dl); + add_running_bw(&p->dl, &later_rq->dl); + } else { + sub_rq_bw(&p->dl, &rq->dl); + add_rq_bw(&p->dl, &later_rq->dl); + } + + /* + * And we finally need to fix up root_domain(s) bandwidth accounting, + * since p is still hanging out in the old (now moved to default) root + * domain. + */ + dl_b = &rq->rd->dl_bw; + raw_spin_lock(&dl_b->lock); + __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span)); + raw_spin_unlock(&dl_b->lock); + + dl_b = &later_rq->rd->dl_bw; + raw_spin_lock(&dl_b->lock); + __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(later_rq->rd->span)); + raw_spin_unlock(&dl_b->lock); + + set_task_cpu(p, later_rq->cpu); + double_unlock_balance(later_rq, rq); + + return later_rq; +} + +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_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, + struct rq *rq) +{ + /* for non-boosted task, pi_of(dl_se) == dl_se */ + dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline; + dl_se->runtime = pi_of(dl_se)->dl_runtime; + + /* + * If it is a deferred reservation, and the server + * is not handling an starvation case, defer it. + */ + if (dl_se->dl_defer && !dl_se->dl_defer_running) { + dl_se->dl_throttled = 1; + dl_se->dl_defer_armed = 1; + } +} + +/* + * 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); + + update_rq_clock(rq); + + WARN_ON(is_dl_boosted(dl_se)); + 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.). + */ + replenish_dl_new_period(dl_se, rq); +} + +static int start_dl_timer(struct sched_dl_entity *dl_se); +static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t); + +/* + * 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 dl_rq *dl_rq = dl_rq_of_se(dl_se); + struct rq *rq = rq_of_dl_rq(dl_rq); + + WARN_ON_ONCE(pi_of(dl_se)->dl_runtime <= 0); + + /* + * This could be the case for a !-dl task that is boosted. + * Just go with full inherited parameters. + * + * Or, it could be the case of a deferred reservation that + * was not able to consume its runtime in background and + * reached this point with current u > U. + * + * In both cases, set a new period. + */ + if (dl_se->dl_deadline == 0 || + (dl_se->dl_defer_armed && dl_entity_overflow(dl_se, rq_clock(rq)))) { + dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline; + dl_se->runtime = pi_of(dl_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_of(dl_se)->dl_period; + dl_se->runtime += pi_of(dl_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"); + replenish_dl_new_period(dl_se, rq); + } + + if (dl_se->dl_yielded) + dl_se->dl_yielded = 0; + if (dl_se->dl_throttled) + dl_se->dl_throttled = 0; + + /* + * If this is the replenishment of a deferred reservation, + * clear the flag and return. + */ + if (dl_se->dl_defer_armed) { + dl_se->dl_defer_armed = 0; + return; + } + + /* + * A this point, if the deferred server is not armed, and the deadline + * is in the future, if it is not running already, throttle the server + * and arm the defer timer. + */ + if (dl_se->dl_defer && !dl_se->dl_defer_running && + dl_time_before(rq_clock(dl_se->rq), dl_se->deadline - dl_se->runtime)) { + if (!is_dl_boosted(dl_se)) { + + /* + * Set dl_se->dl_defer_armed and dl_throttled variables to + * inform the start_dl_timer() that this is a deferred + * activation. + */ + dl_se->dl_defer_armed = 1; + dl_se->dl_throttled = 1; + if (!start_dl_timer(dl_se)) { + /* + * If for whatever reason (delays), a previous timer was + * queued but not serviced, cancel it and clean the + * deferrable server variables intended for start_dl_timer(). + */ + hrtimer_try_to_cancel(&dl_se->dl_timer); + dl_se->dl_defer_armed = 0; + 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.rst for more information). + * + * 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, 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_of(dl_se)->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE); + right = ((dl_se->deadline - t) >> DL_SCALE) * + (pi_of(dl_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 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))) { + + if (unlikely(!dl_is_implicit(dl_se) && + !dl_time_before(dl_se->deadline, rq_clock(rq)) && + !is_dl_boosted(dl_se))) { + update_dl_revised_wakeup(dl_se, rq); + return; + } + + replenish_dl_new_period(dl_se, rq); + } else if (dl_server(dl_se) && dl_se->dl_defer) { + /* + * The server can still use its previous deadline, so check if + * it left the dl_defer_running state. + */ + if (!dl_se->dl_defer_running) { + dl_se->dl_defer_armed = 1; + dl_se->dl_throttled = 1; + } + } +} + +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 sched_dl_entity *dl_se) +{ + struct hrtimer *timer = &dl_se->dl_timer; + 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; + + lockdep_assert_rq_held(rq); + + /* + * 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. + * + * The deferred reservation will have its timer set to + * (deadline - runtime). At that point, the CBS rule will decide + * if the current deadline can be used, or if a replenishment is + * required to avoid add too much pressure on the system + * (current u > U). + */ + if (dl_se->dl_defer_armed) { + WARN_ON_ONCE(!dl_se->dl_throttled); + act = ns_to_ktime(dl_se->deadline - dl_se->runtime); + } else { + /* act = deadline - rel-deadline + period */ + 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)) { + 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) +{ + /* + * 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); + } +} + +/* a defer timer will not be reset if the runtime consumed was < dl_server_min_res */ +static const u64 dl_server_min_res = 1 * NSEC_PER_MSEC; + +static enum hrtimer_restart dl_server_timer(struct hrtimer *timer, struct sched_dl_entity *dl_se) +{ + struct rq *rq = rq_of_dl_se(dl_se); + u64 fw; + + scoped_guard (rq_lock, rq) { + struct rq_flags *rf = &scope.rf; + + if (!dl_se->dl_throttled || !dl_se->dl_runtime) + return HRTIMER_NORESTART; + + sched_clock_tick(); + update_rq_clock(rq); + + /* + * Make sure current has propagated its pending runtime into + * any relevant server through calling dl_server_update() and + * friends. + */ + rq->donor->sched_class->update_curr(rq); + + if (dl_se->dl_defer_idle) { + dl_server_stop(dl_se); + return HRTIMER_NORESTART; + } + + if (dl_se->dl_defer_armed) { + /* + * First check if the server could consume runtime in background. + * If so, it is possible to push the defer timer for this amount + * of time. The dl_server_min_res serves as a limit to avoid + * forwarding the timer for a too small amount of time. + */ + if (dl_time_before(rq_clock(dl_se->rq), + (dl_se->deadline - dl_se->runtime - dl_server_min_res))) { + + /* reset the defer timer */ + fw = dl_se->deadline - rq_clock(dl_se->rq) - dl_se->runtime; + + hrtimer_forward_now(timer, ns_to_ktime(fw)); + return HRTIMER_RESTART; + } + + dl_se->dl_defer_running = 1; + } + + enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH); + + if (!dl_task(dl_se->rq->curr) || dl_entity_preempt(dl_se, &dl_se->rq->curr->dl)) + resched_curr(rq); + + __push_dl_task(rq, rf); + } + + return HRTIMER_NORESTART; +} + +/* + * 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; + struct rq_flags rf; + struct rq *rq; + + if (dl_server(dl_se)) + return dl_server_timer(timer, dl_se); + + p = dl_task_of(dl_se); + 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 (is_dl_boosted(dl_se)) + 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); + goto unlock; + } + + if (unlikely(!rq->online)) { + /* + * If the runqueue is no longer available, migrate the + * task elsewhere. This necessarily changes rq. + */ + lockdep_unpin_lock(__rq_lockp(rq), rf.cookie); + rq = dl_task_offline_migration(rq, p); + rf.cookie = lockdep_pin_lock(__rq_lockp(rq)); + 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. + */ + } + + enqueue_task_dl(rq, p, ENQUEUE_REPLENISH); + if (dl_task(rq->donor)) + wakeup_preempt_dl(rq, p, 0); + else + resched_curr(rq); + + __push_dl_task(rq, &rf); + +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; +} + +static void init_dl_task_timer(struct sched_dl_entity *dl_se) +{ + struct hrtimer *timer = &dl_se->dl_timer; + + hrtimer_setup(timer, dl_task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); +} + +/* + * 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 (deadline < 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 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(dl_se))) + 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); +} + +/* + * 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 - Uinact - Uextra)} / Umax) 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 multiplied by 2^RATIO_SHIFT, dl_bw + * is multiplied 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_act; + u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */ + + /* + * Instead of computing max{u, (u_max - u_inact - u_extra)}, we + * compare u_inact + u_extra with u_max - u, because u_inact + u_extra + * can be larger than u_max. So, u_max - u_inact - u_extra would be + * negative leading to wrong results. + */ + if (u_inact + rq->dl.extra_bw > rq->dl.max_bw - dl_se->dl_bw) + u_act = dl_se->dl_bw; + else + u_act = rq->dl.max_bw - u_inact - rq->dl.extra_bw; + + u_act = (u_act * rq->dl.bw_ratio) >> RATIO_SHIFT; + return (delta * u_act) >> BW_SHIFT; +} + +s64 dl_scaled_delta_exec(struct rq *rq, struct sched_dl_entity *dl_se, s64 delta_exec) +{ + s64 scaled_delta_exec; + + /* + * 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, 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); + + scaled_delta_exec = cap_scale(delta_exec, scale_freq); + scaled_delta_exec = cap_scale(scaled_delta_exec, scale_cpu); + } + + return scaled_delta_exec; +} + +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) +{ + bool idle = rq->curr == rq->idle; + s64 scaled_delta_exec; + + if (unlikely(delta_exec <= 0)) { + if (unlikely(dl_se->dl_yielded)) + goto throttle; + return; + } + + if (dl_server(dl_se) && dl_se->dl_throttled && !dl_se->dl_defer) + return; + + if (dl_entity_is_special(dl_se)) + return; + + scaled_delta_exec = delta_exec; + if (!dl_server(dl_se)) + scaled_delta_exec = dl_scaled_delta_exec(rq, dl_se, delta_exec); + + dl_se->runtime -= scaled_delta_exec; + + if (dl_se->dl_defer_idle && !idle) + dl_se->dl_defer_idle = 0; + + /* + * The fair server can consume its runtime while throttled (not queued/ + * running as regular CFS). + * + * If the server consumes its entire runtime in this state. The server + * is not required for the current period. Thus, reset the server by + * starting a new period, pushing the activation. + */ + if (dl_se->dl_defer && dl_se->dl_throttled && dl_runtime_exceeded(dl_se)) { + /* + * Non-servers would never get time accounted while throttled. + */ + WARN_ON_ONCE(!dl_server(dl_se)); + + /* + * While the server is marked idle, do not push out the + * activation further, instead wait for the period timer + * to lapse and stop the server. + */ + if (dl_se->dl_defer_idle && idle) { + /* + * The timer is at the zero-laxity point, this means + * dl_server_stop() / dl_server_start() can happen + * while now < deadline. This means update_dl_entity() + * will not replenish. Additionally start_dl_timer() + * will be set for 'deadline - runtime'. Negative + * runtime will not do. + */ + dl_se->runtime = 0; + return; + } + + /* + * If the server was previously activated - the starving condition + * took place, it this point it went away because the fair scheduler + * was able to get runtime in background. So return to the initial + * state. + */ + dl_se->dl_defer_running = 0; + + hrtimer_try_to_cancel(&dl_se->dl_timer); + + replenish_dl_new_period(dl_se, dl_se->rq); + + if (idle) + dl_se->dl_defer_idle = 1; + + /* + * Not being able to start the timer seems problematic. If it could not + * be started for whatever reason, we need to "unthrottle" the DL server + * and queue right away. Otherwise nothing might queue it. That's similar + * to what enqueue_dl_entity() does on start_dl_timer==0. For now, just warn. + */ + WARN_ON_ONCE(!start_dl_timer(dl_se)); + + return; + } + +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_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)) { + replenish_dl_new_period(dl_se, rq); + start_dl_timer(dl_se); + } else { + enqueue_task_dl(rq, dl_task_of(dl_se), ENQUEUE_REPLENISH); + } + } + + if (!is_leftmost(dl_se, &rq->dl)) + resched_curr(rq); + } + + /* + * The fair server (sole dl_server) does not account for real-time + * workload because it is running fair work. + */ + if (dl_se == &rq->fair_server) + return; + +#ifdef CONFIG_RT_GROUP_SCHED + /* + * 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); + } +#endif /* CONFIG_RT_GROUP_SCHED */ +} + +/* + * In the non-defer mode, the idle time is not accounted, as the + * server provides a guarantee. + * + * If the dl_server is in defer mode, the idle time is also considered + * as time available for the fair server, avoiding a penalty for the + * rt scheduler that did not consumed that time. + */ +void dl_server_update_idle(struct sched_dl_entity *dl_se, s64 delta_exec) +{ + if (dl_se->dl_server_active && dl_se->dl_runtime && dl_se->dl_defer) + update_curr_dl_se(dl_se->rq, dl_se, delta_exec); +} + +void dl_server_update(struct sched_dl_entity *dl_se, s64 delta_exec) +{ + /* 0 runtime = fair server disabled */ + if (dl_se->dl_server_active && dl_se->dl_runtime) + update_curr_dl_se(dl_se->rq, dl_se, delta_exec); +} + +/* + * dl_server && dl_defer: + * + * 6 + * +--------------------+ + * v | + * +-------------+ 4 +-----------+ 5 +------------------+ + * +-> | A:init | <--- | D:running | -----> | E:replenish-wait | + * | +-------------+ +-----------+ +------------------+ + * | | | 1 ^ ^ | + * | | 1 +----------+ | 3 | + * | v | | + * | +--------------------------------+ 2 | + * | | | ----+ | + * | 8 | B:zero_laxity-wait | | | + * | | | <---+ | + * | +--------------------------------+ | + * | | ^ ^ 2 | + * | | 7 | 2 +--------------------+ + * | v | + * | +-------------+ | + * +-- | C:idle-wait | -+ + * +-------------+ + * ^ 7 | + * +---------+ + * + * + * [A] - init + * dl_server_active = 0 + * dl_throttled = 0 + * dl_defer_armed = 0 + * dl_defer_running = 0/1 + * dl_defer_idle = 0 + * + * [B] - zero_laxity-wait + * dl_server_active = 1 + * dl_throttled = 1 + * dl_defer_armed = 1 + * dl_defer_running = 0 + * dl_defer_idle = 0 + * + * [C] - idle-wait + * dl_server_active = 1 + * dl_throttled = 1 + * dl_defer_armed = 1 + * dl_defer_running = 0 + * dl_defer_idle = 1 + * + * [D] - running + * dl_server_active = 1 + * dl_throttled = 0 + * dl_defer_armed = 0 + * dl_defer_running = 1 + * dl_defer_idle = 0 + * + * [E] - replenish-wait + * dl_server_active = 1 + * dl_throttled = 1 + * dl_defer_armed = 0 + * dl_defer_running = 1 + * dl_defer_idle = 0 + * + * + * [1] A->B, A->D + * dl_server_start() + * dl_server_active = 1; + * enqueue_dl_entity() + * update_dl_entity(WAKEUP) + * if (!dl_defer_running) + * dl_defer_armed = 1; + * dl_throttled = 1; + * if (dl_throttled && start_dl_timer()) + * return; // [B] + * __enqueue_dl_entity(); + * // [D] + * + * // deplete server runtime from client-class + * [2] B->B, C->B, E->B + * dl_server_update() + * update_curr_dl_se() // idle = false + * if (dl_defer_idle) + * dl_defer_idle = 0; + * if (dl_defer && dl_throttled && dl_runtime_exceeded()) + * dl_defer_running = 0; + * hrtimer_try_to_cancel(); // stop timer + * replenish_dl_new_period() + * // fwd period + * dl_throttled = 1; + * dl_defer_armed = 1; + * start_dl_timer(); // restart timer + * // [B] + * + * // timer actually fires means we have runtime + * [3] B->D + * dl_server_timer() + * if (dl_defer_armed) + * dl_defer_running = 1; + * enqueue_dl_entity(REPLENISH) + * replenish_dl_entity() + * // fwd period + * if (dl_throttled) + * dl_throttled = 0; + * if (dl_defer_armed) + * dl_defer_armed = 0; + * __enqueue_dl_entity(); + * // [D] + * + * // schedule server + * [4] D->A + * pick_task_dl() + * p = server_pick_task(); + * if (!p) + * dl_server_stop() + * dequeue_dl_entity(); + * hrtimer_try_to_cancel(); + * dl_defer_armed = 0; + * dl_throttled = 0; + * dl_server_active = 0; + * // [A] + * return p; + * + * // server running + * [5] D->E + * update_curr_dl_se() + * if (dl_runtime_exceeded()) + * dl_throttled = 1; + * dequeue_dl_entity(); + * start_dl_timer(); + * // [E] + * + * // server replenished + * [6] E->D + * dl_server_timer() + * enqueue_dl_entity(REPLENISH) + * replenish_dl_entity() + * fwd-period + * if (dl_throttled) + * dl_throttled = 0; + * __enqueue_dl_entity(); + * // [D] + * + * // deplete server runtime from idle + * [7] B->C, C->C + * dl_server_update_idle() + * update_curr_dl_se() // idle = true + * if (dl_defer && dl_throttled && dl_runtime_exceeded()) + * if (dl_defer_idle) + * return; + * dl_defer_running = 0; + * hrtimer_try_to_cancel(); + * replenish_dl_new_period() + * // fwd period + * dl_throttled = 1; + * dl_defer_armed = 1; + * dl_defer_idle = 1; + * start_dl_timer(); // restart timer + * // [C] + * + * // stop idle server + * [8] C->A + * dl_server_timer() + * if (dl_defer_idle) + * dl_server_stop(); + * // [A] + * + * + * digraph dl_server { + * "A:init" -> "B:zero_laxity-wait" [label="1:dl_server_start"] + * "A:init" -> "D:running" [label="1:dl_server_start"] + * "B:zero_laxity-wait" -> "B:zero_laxity-wait" [label="2:dl_server_update"] + * "B:zero_laxity-wait" -> "C:idle-wait" [label="7:dl_server_update_idle"] + * "B:zero_laxity-wait" -> "D:running" [label="3:dl_server_timer"] + * "C:idle-wait" -> "A:init" [label="8:dl_server_timer"] + * "C:idle-wait" -> "B:zero_laxity-wait" [label="2:dl_server_update"] + * "C:idle-wait" -> "C:idle-wait" [label="7:dl_server_update_idle"] + * "D:running" -> "A:init" [label="4:pick_task_dl"] + * "D:running" -> "E:replenish-wait" [label="5:update_curr_dl_se"] + * "E:replenish-wait" -> "B:zero_laxity-wait" [label="2:dl_server_update"] + * "E:replenish-wait" -> "D:running" [label="6:dl_server_timer"] + * } + * + * + * Notes: + * + * - When there are fair tasks running the most likely loop is [2]->[2]. + * the dl_server never actually runs, the timer never fires. + * + * - When there is actual fair starvation; the timer fires and starts the + * dl_server. This will then throttle and replenish like a normal DL + * task. Notably it will not 'defer' again. + * + * - When idle it will push the actication forward once, and then wait + * for the timer to hit or a non-idle update to restart things. + */ +void dl_server_start(struct sched_dl_entity *dl_se) +{ + struct rq *rq = dl_se->rq; + + if (!dl_server(dl_se) || dl_se->dl_server_active) + return; + + /* + * Update the current task to 'now'. + */ + rq->donor->sched_class->update_curr(rq); + + if (WARN_ON_ONCE(!cpu_online(cpu_of(rq)))) + return; + + dl_se->dl_server_active = 1; + enqueue_dl_entity(dl_se, ENQUEUE_WAKEUP); + if (!dl_task(dl_se->rq->curr) || dl_entity_preempt(dl_se, &rq->curr->dl)) + resched_curr(dl_se->rq); +} + +void dl_server_stop(struct sched_dl_entity *dl_se) +{ + if (!dl_server(dl_se) || !dl_server_active(dl_se)) + return; + + dequeue_dl_entity(dl_se, DEQUEUE_SLEEP); + hrtimer_try_to_cancel(&dl_se->dl_timer); + dl_se->dl_defer_armed = 0; + dl_se->dl_throttled = 0; + dl_se->dl_defer_idle = 0; + dl_se->dl_server_active = 0; +} + +void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq, + dl_server_pick_f pick_task) +{ + dl_se->rq = rq; + dl_se->server_pick_task = pick_task; +} + +void sched_init_dl_servers(void) +{ + int cpu; + struct rq *rq; + struct sched_dl_entity *dl_se; + + for_each_online_cpu(cpu) { + u64 runtime = 50 * NSEC_PER_MSEC; + u64 period = 1000 * NSEC_PER_MSEC; + + rq = cpu_rq(cpu); + + guard(rq_lock_irq)(rq); + + dl_se = &rq->fair_server; + + WARN_ON(dl_server(dl_se)); + + dl_server_apply_params(dl_se, runtime, period, 1); + + dl_se->dl_server = 1; + dl_se->dl_defer = 1; + setup_new_dl_entity(dl_se); + } +} + +void __dl_server_attach_root(struct sched_dl_entity *dl_se, struct rq *rq) +{ + u64 new_bw = dl_se->dl_bw; + int cpu = cpu_of(rq); + struct dl_bw *dl_b; + + dl_b = dl_bw_of(cpu_of(rq)); + guard(raw_spinlock)(&dl_b->lock); + + if (!dl_bw_cpus(cpu)) + return; + + __dl_add(dl_b, new_bw, dl_bw_cpus(cpu)); +} + +int dl_server_apply_params(struct sched_dl_entity *dl_se, u64 runtime, u64 period, bool init) +{ + u64 old_bw = init ? 0 : to_ratio(dl_se->dl_period, dl_se->dl_runtime); + u64 new_bw = to_ratio(period, runtime); + struct rq *rq = dl_se->rq; + int cpu = cpu_of(rq); + struct dl_bw *dl_b; + unsigned long cap; + int retval = 0; + int cpus; + + dl_b = dl_bw_of(cpu); + guard(raw_spinlock)(&dl_b->lock); + + cpus = dl_bw_cpus(cpu); + cap = dl_bw_capacity(cpu); + + if (__dl_overflow(dl_b, cap, old_bw, new_bw)) + return -EBUSY; + + if (init) { + __add_rq_bw(new_bw, &rq->dl); + __dl_add(dl_b, new_bw, cpus); + } else { + __dl_sub(dl_b, dl_se->dl_bw, cpus); + __dl_add(dl_b, new_bw, cpus); + + dl_rq_change_utilization(rq, dl_se, new_bw); + } + + dl_se->dl_runtime = runtime; + dl_se->dl_deadline = period; + dl_se->dl_period = period; + + dl_se->runtime = 0; + dl_se->deadline = 0; + + 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); + + return retval; +} + +/* + * 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 *donor = rq->donor; + struct sched_dl_entity *dl_se = &donor->dl; + s64 delta_exec; + + if (!dl_task(donor) || !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 = NULL; + struct rq_flags rf; + struct rq *rq; + + 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)); + + if (READ_ONCE(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(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: + + if (!dl_server(dl_se)) { + task_rq_unlock(rq, p, &rf); + put_task_struct(p); + } else { + rq_unlock(rq, &rf); + } + + return HRTIMER_NORESTART; +} + +static void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se) +{ + struct hrtimer *timer = &dl_se->inactive_timer; + + hrtimer_setup(timer, inactive_task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); +} + +#define __node_2_dle(node) \ + rb_entry((node), struct sched_dl_entity, rb_node) + +static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) +{ + struct rq *rq = rq_of_dl_rq(dl_rq); + + if (dl_rq->earliest_dl.curr == 0 || + dl_time_before(deadline, dl_rq->earliest_dl.curr)) { + if (dl_rq->earliest_dl.curr == 0) + cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER); + 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, rq->online); + cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr); + } else { + struct rb_node *leftmost = rb_first_cached(&dl_rq->root); + struct sched_dl_entity *entry = __node_2_dle(leftmost); + + dl_rq->earliest_dl.curr = entry->deadline; + cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline); + } +} + +static inline +void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) +{ + u64 deadline = dl_se->deadline; + + dl_rq->dl_nr_running++; + + if (!dl_server(dl_se)) + add_nr_running(rq_of_dl_rq(dl_rq), 1); + + inc_dl_deadline(dl_rq, deadline); +} + +static inline +void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) +{ + WARN_ON(!dl_rq->dl_nr_running); + dl_rq->dl_nr_running--; + + if (!dl_server(dl_se)) + sub_nr_running(rq_of_dl_rq(dl_rq), 1); + + dec_dl_deadline(dl_rq, dl_se->deadline); +} + +static inline bool __dl_less(struct rb_node *a, const struct rb_node *b) +{ + return dl_time_before(__node_2_dle(a)->deadline, __node_2_dle(b)->deadline); +} + +static __always_inline struct sched_statistics * +__schedstats_from_dl_se(struct sched_dl_entity *dl_se) +{ + if (!schedstat_enabled()) + return NULL; + + if (dl_server(dl_se)) + return NULL; + + return &dl_task_of(dl_se)->stats; +} + +static inline void +update_stats_wait_start_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se) +{ + struct sched_statistics *stats = __schedstats_from_dl_se(dl_se); + if (stats) + __update_stats_wait_start(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats); +} + +static inline void +update_stats_wait_end_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se) +{ + struct sched_statistics *stats = __schedstats_from_dl_se(dl_se); + if (stats) + __update_stats_wait_end(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats); +} + +static inline void +update_stats_enqueue_sleeper_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se) +{ + struct sched_statistics *stats = __schedstats_from_dl_se(dl_se); + if (stats) + __update_stats_enqueue_sleeper(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats); +} + +static inline void +update_stats_enqueue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se, + int flags) +{ + if (!schedstat_enabled()) + return; + + if (flags & ENQUEUE_WAKEUP) + update_stats_enqueue_sleeper_dl(dl_rq, dl_se); +} + +static inline void +update_stats_dequeue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se, + int flags) +{ + struct task_struct *p = dl_task_of(dl_se); + + if (!schedstat_enabled()) + return; + + if ((flags & DEQUEUE_SLEEP)) { + unsigned int state; + + state = READ_ONCE(p->__state); + if (state & TASK_INTERRUPTIBLE) + __schedstat_set(p->stats.sleep_start, + rq_clock(rq_of_dl_rq(dl_rq))); + + if (state & TASK_UNINTERRUPTIBLE) + __schedstat_set(p->stats.block_start, + rq_clock(rq_of_dl_rq(dl_rq))); + } +} + +static void __enqueue_dl_entity(struct sched_dl_entity *dl_se) +{ + struct dl_rq *dl_rq = dl_rq_of_se(dl_se); + + WARN_ON_ONCE(!RB_EMPTY_NODE(&dl_se->rb_node)); + + rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less); + + 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, int flags) +{ + WARN_ON_ONCE(on_dl_rq(dl_se)); + + 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_defer && 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. + */ + if (flags & ENQUEUE_WAKEUP) { + task_contending(dl_se, flags); + update_dl_entity(dl_se); + } else if (flags & ENQUEUE_REPLENISH) { + replenish_dl_entity(dl_se); + } else if ((flags & ENQUEUE_RESTORE) && + !is_dl_boosted(dl_se) && + dl_time_before(dl_se->deadline, rq_clock(rq_of_dl_se(dl_se)))) { + setup_new_dl_entity(dl_se); + } + + /* + * If the reservation is still throttled, e.g., it got replenished but is a + * deferred task and still got to wait, don't enqueue. + */ + if (dl_se->dl_throttled && start_dl_timer(dl_se)) + return; + + /* + * We're about to enqueue, make sure we're not ->dl_throttled! + * In case the timer was not started, say because the defer time + * has passed, mark as not throttled and mark unarmed. + * Also cancel earlier timers, since letting those run is pointless. + */ + if (dl_se->dl_throttled) { + hrtimer_try_to_cancel(&dl_se->dl_timer); + dl_se->dl_defer_armed = 0; + dl_se->dl_throttled = 0; + } + + __enqueue_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, true); +} + +static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) +{ + if (is_dl_boosted(&p->dl)) { + /* + * Because of delays in the detection of the overrun of a + * thread's runtime, it might be the case that a thread + * goes to sleep in a rt mutex with negative runtime. As + * a consequence, the thread will be throttled. + * + * While waiting for the mutex, this thread can also be + * boosted via PI, resulting in a thread that is throttled + * and boosted at the same time. + * + * In this case, the boost overrides the throttle. + */ + if (p->dl.dl_throttled) { + /* + * The replenish timer needs to be canceled. No + * problem if it fires concurrently: boosted threads + * are ignored in dl_task_timer(). + */ + cancel_replenish_timer(&p->dl); + p->dl.dl_throttled = 0; + } + } 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. If it has been throttled, we need to + * clear the flag, otherwise the task may wake up as throttled after + * being boosted again with no means to replenish the runtime and clear + * the throttle. + */ + p->dl.dl_throttled = 0; + if (!(flags & ENQUEUE_REPLENISH)) + printk_deferred_once("sched: DL de-boosted task PID %d: REPLENISH flag missing\n", + task_pid_nr(p)); + + 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 (dl_server(&p->dl)) + return; + + if (task_is_blocked(p)) + return; + + if (!task_current(rq, p) && !p->dl.dl_throttled && p->nr_cpus_allowed > 1) + enqueue_pushable_dl_task(rq, p); +} + +static bool dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) +{ + update_curr_dl(rq); + + if (p->on_rq == TASK_ON_RQ_MIGRATING) + flags |= DEQUEUE_MIGRATING; + + dequeue_dl_entity(&p->dl, flags); + if (!p->dl.dl_throttled && !dl_server(&p->dl)) + dequeue_pushable_dl_task(rq, p); + + return true; +} + +/* + * 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->donor->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); +} + +static inline bool dl_task_is_earliest_deadline(struct task_struct *p, + struct rq *rq) +{ + return (!rq->dl.dl_nr_running || + dl_time_before(p->dl.deadline, + rq->dl.earliest_dl.curr)); +} + +static int find_later_rq(struct task_struct *task); + +static int +select_task_rq_dl(struct task_struct *p, int cpu, int flags) +{ + struct task_struct *curr, *donor; + bool select_rq; + struct rq *rq; + + if (!(flags & WF_TTWU)) + return cpu; + + rq = cpu_rq(cpu); + + rcu_read_lock(); + curr = READ_ONCE(rq->curr); /* unlocked access */ + donor = READ_ONCE(rq->donor); + + /* + * 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. + */ + select_rq = unlikely(dl_task(donor)) && + (curr->nr_cpus_allowed < 2 || + !dl_entity_preempt(&p->dl, &donor->dl)) && + p->nr_cpus_allowed > 1; + + /* + * Take the capacity of the CPU into account to + * ensure it fits the requirement of the task. + */ + if (sched_asym_cpucap_active()) + select_rq |= !dl_task_fits_capacity(p, cpu); + + if (select_rq) { + int target = find_later_rq(p); + + if (target != -1 && + dl_task_is_earliest_deadline(p, cpu_rq(target))) + cpu = target; + } + rcu_read_unlock(); + + return cpu; +} + +static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused) +{ + struct rq_flags rf; + struct rq *rq; + + if (READ_ONCE(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 + */ + rq_lock(rq, &rf); + if (p->dl.dl_non_contending) { + update_rq_clock(rq); + 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 canceled, 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. + */ + cancel_inactive_timer(&p->dl); + } + sub_rq_bw(&p->dl, &rq->dl); + rq_unlock(rq, &rf); +} + +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->donor, 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); +} + +static int balance_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf) +{ + if (!on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) { + /* + * 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've + * not yet started the picking loop. + */ + rq_unpin_lock(rq, rf); + pull_dl_task(rq); + rq_repin_lock(rq, rf); + } + + return sched_stop_runnable(rq) || sched_dl_runnable(rq); +} + +/* + * Only called when both the current and waking task are -deadline + * tasks. + */ +static void wakeup_preempt_dl(struct rq *rq, struct task_struct *p, + int flags) +{ + if (dl_entity_preempt(&p->dl, &rq->donor->dl)) { + resched_curr(rq); + return; + } + + /* + * 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->donor->dl.deadline) && + !test_tsk_need_resched(rq->curr)) + check_preempt_equal_dl(rq, p); +} + +#ifdef CONFIG_SCHED_HRTICK +static void start_hrtick_dl(struct rq *rq, struct sched_dl_entity *dl_se) +{ + hrtick_start(rq, dl_se->runtime); +} +#else /* !CONFIG_SCHED_HRTICK: */ +static void start_hrtick_dl(struct rq *rq, struct sched_dl_entity *dl_se) +{ +} +#endif /* !CONFIG_SCHED_HRTICK */ + +static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first) +{ + struct sched_dl_entity *dl_se = &p->dl; + struct dl_rq *dl_rq = &rq->dl; + + p->se.exec_start = rq_clock_task(rq); + if (on_dl_rq(&p->dl)) + update_stats_wait_end_dl(dl_rq, dl_se); + + /* You can't push away the running task */ + dequeue_pushable_dl_task(rq, p); + + if (!first) + return; + + if (rq->donor->sched_class != &dl_sched_class) + update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0); + + deadline_queue_push_tasks(rq); + + if (hrtick_enabled_dl(rq)) + start_hrtick_dl(rq, &p->dl); +} + +static struct sched_dl_entity *pick_next_dl_entity(struct dl_rq *dl_rq) +{ + struct rb_node *left = rb_first_cached(&dl_rq->root); + + if (!left) + return NULL; + + return __node_2_dle(left); +} + +/* + * __pick_next_task_dl - Helper to pick the next -deadline task to run. + * @rq: The runqueue to pick the next task from. + */ +static struct task_struct *__pick_task_dl(struct rq *rq, struct rq_flags *rf) +{ + struct sched_dl_entity *dl_se; + 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); + + if (dl_server(dl_se)) { + p = dl_se->server_pick_task(dl_se, rf); + if (!p) { + dl_server_stop(dl_se); + goto again; + } + rq->dl_server = dl_se; + } else { + p = dl_task_of(dl_se); + } + + return p; +} + +static struct task_struct *pick_task_dl(struct rq *rq, struct rq_flags *rf) +{ + return __pick_task_dl(rq, rf); +} + +static void put_prev_task_dl(struct rq *rq, struct task_struct *p, struct task_struct *next) +{ + struct sched_dl_entity *dl_se = &p->dl; + struct dl_rq *dl_rq = &rq->dl; + + if (on_dl_rq(&p->dl)) + update_stats_wait_start_dl(dl_rq, dl_se); + + update_curr_dl(rq); + + update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1); + + if (task_is_blocked(p)) + return; + + 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_pelt(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_dl(rq) && queued && p->dl.runtime > 0 && + is_leftmost(&p->dl, &rq->dl)) + start_hrtick_dl(rq, &p->dl); +} + +static void task_fork_dl(struct task_struct *p) +{ + /* + * SCHED_DEADLINE tasks cannot fork and this is achieved through + * sched_fork() + */ +} + +/* Only try algorithms three times */ +#define DL_MAX_TRIES 3 + +/* + * 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 task_struct *p = NULL; + struct rb_node *next_node; + + if (!has_pushable_dl_tasks(rq)) + return NULL; + + next_node = rb_first_cached(&rq->dl.pushable_dl_tasks_root); + while (next_node) { + p = __node_2_pdl(next_node); + + if (task_is_pushable(rq, p, cpu)) + return p; + + next_node = rb_next(next_node); + } + + return NULL; +} + +/* Access rule: must be called on local CPU with preemption disabled */ +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_any_and_distribute(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_distribute(later_mask); + if (cpu < nr_cpu_ids) + return cpu; + + return -1; +} + +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 = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root)); + + WARN_ON_ONCE(rq->cpu != task_cpu(p)); + WARN_ON_ONCE(task_current(rq, p)); + WARN_ON_ONCE(p->nr_cpus_allowed <= 1); + + WARN_ON_ONCE(!task_on_rq_queued(p)); + WARN_ON_ONCE(!dl_task(p)); + + return p; +} + +/* 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 (!dl_task_is_earliest_deadline(task, later_rq)) { + /* + * 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)) { + /* + * double_lock_balance had to release rq->lock, in the + * meantime, task may no longer be fit to be migrated. + * Check the following to ensure that the task is + * still suitable for migration: + * 1. It is possible the task was scheduled, + * migrate_disabled was set and then got preempted, + * so we must check the task migration disable + * flag. + * 2. The CPU picked is in the task's affinity. + * 3. For throttled task (dl_task_offline_migration), + * check the following: + * - the task is not on the rq anymore (it was + * migrated) + * - the task is not on CPU anymore + * - the task is still a dl task + * - the task is not queued on the rq anymore + * 4. For the non-throttled task (push_dl_task), the + * check to ensure that this task is still at the + * head of the pushable tasks list is enough. + */ + if (unlikely(is_migration_disabled(task) || + !cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) || + (task->dl.dl_throttled && + (task_rq(task) != rq || + task_on_cpu(rq, task) || + !dl_task(task) || + !task_on_rq_queued(task))) || + (!task->dl.dl_throttled && + task != pick_next_pushable_dl_task(rq)))) { + + double_unlock_balance(rq, later_rq); + later_rq = NULL; + break; + } + } + + /* + * If the rq we found has no -deadline task, or + * its earliest one has a later deadline than our + * task, the rq is a good one. + */ + if (dl_task_is_earliest_deadline(task, later_rq)) + break; + + /* Otherwise we try again. */ + double_unlock_balance(rq, later_rq); + later_rq = NULL; + } + + return later_rq; +} + +/* + * 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; + + next_task = pick_next_pushable_dl_task(rq); + if (!next_task) + return 0; + +retry: + /* + * 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->donor) && + dl_time_before(next_task->dl.deadline, rq->donor->dl.deadline) && + rq->curr->nr_cpus_allowed > 1) { + resched_curr(rq); + return 0; + } + + if (is_migration_disabled(next_task)) + return 0; + + if (WARN_ON(next_task == rq->curr)) + return 0; + + /* We might release rq lock */ + get_task_struct(next_task); + + /* Will lock the rq it'll find */ + later_rq = find_lock_later_rq(next_task, rq); + if (!later_rq) { + struct task_struct *task; + + /* + * We must check all this again, since + * find_lock_later_rq releases rq->lock and it is + * then possible that next_task has migrated. + */ + task = pick_next_pushable_dl_task(rq); + if (task == 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; + } + + move_queued_task_locked(rq, later_rq, next_task); + 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, *push_task; + 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, and 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 */ + push_task = NULL; + 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) && + dl_task_is_earliest_deadline(p, this_rq)) { + 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->donor->dl.deadline)) + goto skip; + + if (is_migration_disabled(p)) { + push_task = get_push_task(src_rq); + } else { + move_queued_task_locked(src_rq, this_rq, p); + dmin = p->dl.deadline; + resched = true; + } + + /* Is there any other task even earlier? */ + } +skip: + double_unlock_balance(this_rq, src_rq); + + if (push_task) { + preempt_disable(); + raw_spin_rq_unlock(this_rq); + stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop, + push_task, &src_rq->push_work); + preempt_enable(); + raw_spin_rq_lock(this_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_on_cpu(rq, p) && + !test_tsk_need_resched(rq->curr) && + p->nr_cpus_allowed > 1 && + dl_task(rq->donor) && + (rq->curr->nr_cpus_allowed < 2 || + !dl_entity_preempt(&p->dl, &rq->donor->dl))) { + push_dl_tasks(rq); + } +} + +static void set_cpus_allowed_dl(struct task_struct *p, + struct affinity_context *ctx) +{ + struct root_domain *src_rd; + struct rq *rq; + + WARN_ON_ONCE(!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, ctx->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, ctx); +} + +/* Assumes rq->lock is held */ +static void rq_online_dl(struct rq *rq) +{ + if (rq->dl.overloaded) + dl_set_overload(rq); + + if (rq->dl.dl_nr_running > 0) + cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr); + else + cpudl_clear(&rq->rd->cpudl, rq->cpu, true); +} + +/* 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, false); +} + +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)); +} + +/* + * This function always returns a non-empty bitmap in @cpus. This is because + * if a root domain has reserved bandwidth for DL tasks, the DL bandwidth + * check will prevent CPU hotplug from deactivating all CPUs in that domain. + */ +static void dl_get_task_effective_cpus(struct task_struct *p, struct cpumask *cpus) +{ + const struct cpumask *hk_msk; + + hk_msk = housekeeping_cpumask(HK_TYPE_DOMAIN); + if (housekeeping_enabled(HK_TYPE_DOMAIN)) { + if (!cpumask_intersects(p->cpus_ptr, hk_msk)) { + /* + * CPUs isolated by isolcpu="domain" always belong to + * def_root_domain. + */ + cpumask_andnot(cpus, cpu_active_mask, hk_msk); + return; + } + } + + /* + * If a root domain holds a DL task, it must have active CPUs. So + * active CPUs can always be found by walking up the task's cpuset + * hierarchy up to the partition root. + */ + cpuset_cpus_allowed_locked(p, cpus); +} + +/* The caller should hold cpuset_mutex */ +void dl_add_task_root_domain(struct task_struct *p) +{ + struct rq_flags rf; + struct rq *rq; + struct dl_bw *dl_b; + unsigned int cpu; + struct cpumask *msk = this_cpu_cpumask_var_ptr(local_cpu_mask_dl); + + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); + if (!dl_task(p) || dl_entity_is_special(&p->dl)) { + raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); + return; + } + + /* + * Get an active rq, whose rq->rd traces the correct root + * domain. + * Ideally this would be under cpuset reader lock until rq->rd is + * fetched. However, sleepable locks cannot nest inside pi_lock, so we + * rely on the caller of dl_add_task_root_domain() holds 'cpuset_mutex' + * to guarantee the CPU stays in the cpuset. + */ + dl_get_task_effective_cpus(p, msk); + cpu = cpumask_first_and(cpu_active_mask, msk); + BUG_ON(cpu >= nr_cpu_ids); + rq = cpu_rq(cpu); + dl_b = &rq->rd->dl_bw; + /* End of fetching rd */ + + raw_spin_lock(&dl_b->lock); + __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span)); + raw_spin_unlock(&dl_b->lock); + raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); +} + +void dl_clear_root_domain(struct root_domain *rd) +{ + int i; + + guard(raw_spinlock_irqsave)(&rd->dl_bw.lock); + + /* + * Reset total_bw to zero and extra_bw to max_bw so that next + * loop will add dl-servers contributions back properly, + */ + rd->dl_bw.total_bw = 0; + for_each_cpu(i, rd->span) + cpu_rq(i)->dl.extra_bw = cpu_rq(i)->dl.max_bw; + + /* + * dl_servers are not tasks. Since dl_add_task_root_domain ignores + * them, we need to account for them here explicitly. + */ + for_each_cpu(i, rd->span) { + struct sched_dl_entity *dl_se = &cpu_rq(i)->fair_server; + + if (dl_server(dl_se) && cpu_active(i)) + __dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(i)); + } +} + +void dl_clear_root_domain_cpu(int cpu) +{ + dl_clear_root_domain(cpu_rq(cpu)->rd); +} + +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->dl, false); + + /* + * In case a task is setscheduled out from SCHED_DEADLINE we need to + * keep track of that on its cpuset (for correct bandwidth tracking). + */ + dec_dl_tasks_cs(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) +{ + cancel_inactive_timer(&p->dl); + + /* + * In case a task is setscheduled to SCHED_DEADLINE we need to keep + * track of that on its cpuset (for correct bandwidth tracking). + */ + inc_dl_tasks_cs(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->donor != p) { + if (p->nr_cpus_allowed > 1 && rq->dl.overloaded) + deadline_queue_push_tasks(rq); + if (dl_task(rq->donor)) + wakeup_preempt_dl(rq, p, 0); + else + resched_curr(rq); + } else { + update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0); + } +} + +static u64 get_prio_dl(struct rq *rq, struct task_struct *p) +{ + return p->dl.deadline; +} + +/* + * 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, u64 old_deadline) +{ + if (!task_on_rq_queued(p)) + return; + + if (p->dl.deadline == old_deadline) + return; + + if (dl_time_before(old_deadline, p->dl.deadline)) + deadline_queue_pull_task(rq); + + if (task_current_donor(rq, p)) { + /* + * 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 { + /* + * Current may not be deadline in case p was throttled but we + * have just replenished it (e.g. rt_mutex_setprio()). + * + * Otherwise, if p was given an earlier deadline, reschedule. + */ + if (!dl_task(rq->curr) || + dl_time_before(p->dl.deadline, rq->curr->dl.deadline)) + resched_curr(rq); + } +} + +#ifdef CONFIG_SCHED_CORE +static int task_is_throttled_dl(struct task_struct *p, int cpu) +{ + return p->dl.dl_throttled; +} +#endif + +DEFINE_SCHED_CLASS(dl) = { + + .queue_mask = 8, + + .enqueue_task = enqueue_task_dl, + .dequeue_task = dequeue_task_dl, + .yield_task = yield_task_dl, + + .wakeup_preempt = wakeup_preempt_dl, + + .pick_task = pick_task_dl, + .put_prev_task = put_prev_task_dl, + .set_next_task = set_next_task_dl, + + .balance = balance_dl, + .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, + .find_lock_rq = find_lock_later_rq, + + .task_tick = task_tick_dl, + .task_fork = task_fork_dl, + + .get_prio = get_prio_dl, + .prio_changed = prio_changed_dl, + .switched_from = switched_from_dl, + .switched_to = switched_to_dl, + + .update_curr = update_curr_dl, +#ifdef CONFIG_SCHED_CORE + .task_is_throttled = task_is_throttled_dl, +#endif +}; + +/* + * Used for dl_bw check and update, used under sched_rt_handler()::mutex and + * sched_domains_mutex. + */ +u64 dl_cookie; + +int sched_dl_global_validate(void) +{ + u64 runtime = global_rt_runtime(); + u64 period = global_rt_period(); + u64 new_bw = to_ratio(period, runtime); + u64 cookie = ++dl_cookie; + struct dl_bw *dl_b; + int cpu, cpus, 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. + */ + for_each_online_cpu(cpu) { + rcu_read_lock_sched(); + + if (dl_bw_visited(cpu, cookie)) + goto next; + + dl_b = dl_bw_of(cpu); + cpus = dl_bw_cpus(cpu); + + raw_spin_lock_irqsave(&dl_b->lock, flags); + if (new_bw * cpus < dl_b->total_bw) + ret = -EBUSY; + raw_spin_unlock_irqrestore(&dl_b->lock, flags); + +next: + rcu_read_unlock_sched(); + + if (ret) + break; + } + + return ret; +} + +static 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->max_bw = 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->max_bw = dl_rq->extra_bw = + to_ratio(global_rt_period(), global_rt_runtime()); + } +} + +void sched_dl_do_global(void) +{ + u64 new_bw = -1; + u64 cookie = ++dl_cookie; + struct dl_bw *dl_b; + int cpu; + unsigned long flags; + + if (global_rt_runtime() != RUNTIME_INF) + new_bw = to_ratio(global_rt_period(), global_rt_runtime()); + + for_each_possible_cpu(cpu) + init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl); + + for_each_possible_cpu(cpu) { + rcu_read_lock_sched(); + + if (dl_bw_visited(cpu, cookie)) { + rcu_read_unlock_sched(); + continue; + } + + 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(); + } +} + +/* + * 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) +{ + 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, cpu = task_cpu(p); + struct dl_bw *dl_b = dl_bw_of(cpu); + unsigned long cap; + + 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(cpu); + cap = dl_bw_capacity(cpu); + + if (dl_policy(policy) && !task_has_dl_policy(p) && + !__dl_overflow(dl_b, cap, 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, cap, 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 & SCHED_DL_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 &= ~SCHED_DL_FLAGS; + 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) +{ + u64 period, max, min; + + /* 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; + + period = attr->sched_period; + if (!period) + period = attr->sched_deadline; + + /* runtime <= deadline <= period (if period != 0) */ + if (period < attr->sched_deadline || + attr->sched_deadline < attr->sched_runtime) + return false; + + max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC; + min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC; + + if (period < min || period > max) + return false; + + return true; +} + +/* + * This function clears the sched_dl_entity static params. + */ +static void __dl_clear_params(struct sched_dl_entity *dl_se) +{ + 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; + 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; + + 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 & SCHED_DL_FLAGS)) + return true; + + return false; +} + +int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, + const struct cpumask *trial) +{ + unsigned long flags, cap; + struct dl_bw *cur_dl_b; + int ret = 1; + + rcu_read_lock_sched(); + cur_dl_b = dl_bw_of(cpumask_any(cur)); + cap = __dl_bw_capacity(trial); + raw_spin_lock_irqsave(&cur_dl_b->lock, flags); + if (__dl_overflow(cur_dl_b, cap, 0, 0)) + ret = 0; + raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags); + rcu_read_unlock_sched(); + + return ret; +} + +enum dl_bw_request { + dl_bw_req_deactivate = 0, + dl_bw_req_alloc, + dl_bw_req_free +}; + +static int dl_bw_manage(enum dl_bw_request req, int cpu, u64 dl_bw) +{ + unsigned long flags, cap; + struct dl_bw *dl_b; + bool overflow = 0; + u64 fair_server_bw = 0; + + rcu_read_lock_sched(); + dl_b = dl_bw_of(cpu); + raw_spin_lock_irqsave(&dl_b->lock, flags); + + cap = dl_bw_capacity(cpu); + switch (req) { + case dl_bw_req_free: + __dl_sub(dl_b, dl_bw, dl_bw_cpus(cpu)); + break; + case dl_bw_req_alloc: + overflow = __dl_overflow(dl_b, cap, 0, dl_bw); + + if (!overflow) { + /* + * We reserve space 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, dl_bw, dl_bw_cpus(cpu)); + } + break; + case dl_bw_req_deactivate: + /* + * cpu is not off yet, but we need to do the math by + * considering it off already (i.e., what would happen if we + * turn cpu off?). + */ + cap -= arch_scale_cpu_capacity(cpu); + + /* + * cpu is going offline and NORMAL tasks will be moved away + * from it. We can thus discount dl_server bandwidth + * contribution as it won't need to be servicing tasks after + * the cpu is off. + */ + if (cpu_rq(cpu)->fair_server.dl_server) + fair_server_bw = cpu_rq(cpu)->fair_server.dl_bw; + + /* + * Not much to check if no DEADLINE bandwidth is present. + * dl_servers we can discount, as tasks will be moved out the + * offlined CPUs anyway. + */ + if (dl_b->total_bw - fair_server_bw > 0) { + /* + * Leaving at least one CPU for DEADLINE tasks seems a + * wise thing to do. As said above, cpu is not offline + * yet, so account for that. + */ + if (dl_bw_cpus(cpu) - 1) + overflow = __dl_overflow(dl_b, cap, fair_server_bw, 0); + else + overflow = 1; + } + + break; + } + + raw_spin_unlock_irqrestore(&dl_b->lock, flags); + rcu_read_unlock_sched(); + + return overflow ? -EBUSY : 0; +} + +int dl_bw_deactivate(int cpu) +{ + return dl_bw_manage(dl_bw_req_deactivate, cpu, 0); +} + +int dl_bw_alloc(int cpu, u64 dl_bw) +{ + return dl_bw_manage(dl_bw_req_alloc, cpu, dl_bw); +} + +void dl_bw_free(int cpu, u64 dl_bw) +{ + dl_bw_manage(dl_bw_req_free, cpu, dl_bw); +} + +void print_dl_stats(struct seq_file *m, int cpu) +{ + print_dl_rq(m, cpu, &cpu_rq(cpu)->dl); +} |