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![Linus Torvalds](/assets/img/avatar_default.png)
Pull cgroup updates from Tejun Heo: "Cgroup2 cpu controller support is finally merged. - Basic cpu statistics support to allow monitoring by default without the CPU controller enabled. - cgroup2 cpu controller support. - /sys/kernel/cgroup files to help dealing with new / optional features" * 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: export list of cgroups v2 features using sysfs cgroup: export list of delegatable control files using sysfs cgroup: mark @cgrp __maybe_unused in cpu_stat_show() MAINTAINERS: relocate cpuset.c cgroup, sched: Move basic cpu stats from cgroup.stat to cpu.stat sched: Implement interface for cgroup unified hierarchy sched: Misc preps for cgroup unified hierarchy interface sched/cputime: Add dummy cputime_adjust() implementation for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE cgroup: statically initialize init_css_set->dfl_cgrp cgroup: Implement cgroup2 basic CPU usage accounting cpuacct: Introduce cgroup_account_cputime[_field]() sched/cputime: Expose cputime_adjust()
2661 lines
72 KiB
C
2661 lines
72 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Deadline Scheduling Class (SCHED_DEADLINE)
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*
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* Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
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*
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* Tasks that periodically executes their instances for less than their
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* runtime won't miss any of their deadlines.
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* Tasks that are not periodic or sporadic or that tries to execute more
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* than their reserved bandwidth will be slowed down (and may potentially
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* miss some of their deadlines), and won't affect any other task.
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*
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* Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
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* Juri Lelli <juri.lelli@gmail.com>,
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* Michael Trimarchi <michael@amarulasolutions.com>,
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* Fabio Checconi <fchecconi@gmail.com>
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*/
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#include "sched.h"
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#include <linux/slab.h>
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#include <uapi/linux/sched/types.h>
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struct dl_bandwidth def_dl_bandwidth;
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static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
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{
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return container_of(dl_se, struct task_struct, dl);
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}
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static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
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{
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return container_of(dl_rq, struct rq, dl);
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}
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static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
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{
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struct task_struct *p = dl_task_of(dl_se);
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struct rq *rq = task_rq(p);
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return &rq->dl;
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}
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static inline int on_dl_rq(struct sched_dl_entity *dl_se)
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{
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return !RB_EMPTY_NODE(&dl_se->rb_node);
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}
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#ifdef CONFIG_SMP
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static inline struct dl_bw *dl_bw_of(int i)
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{
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RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
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"sched RCU must be held");
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return &cpu_rq(i)->rd->dl_bw;
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}
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static inline int dl_bw_cpus(int i)
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{
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struct root_domain *rd = cpu_rq(i)->rd;
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int cpus = 0;
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RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
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"sched RCU must be held");
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for_each_cpu_and(i, rd->span, cpu_active_mask)
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cpus++;
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return cpus;
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}
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#else
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static inline struct dl_bw *dl_bw_of(int i)
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{
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return &cpu_rq(i)->dl.dl_bw;
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}
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static inline int dl_bw_cpus(int i)
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{
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return 1;
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}
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#endif
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static inline
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void add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
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{
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u64 old = dl_rq->running_bw;
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lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock);
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dl_rq->running_bw += dl_bw;
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SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */
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SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
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}
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static inline
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void sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
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{
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u64 old = dl_rq->running_bw;
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lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock);
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dl_rq->running_bw -= dl_bw;
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SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */
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if (dl_rq->running_bw > old)
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dl_rq->running_bw = 0;
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}
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static inline
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void add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
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{
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u64 old = dl_rq->this_bw;
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lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock);
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dl_rq->this_bw += dl_bw;
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SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */
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}
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static inline
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void sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
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{
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u64 old = dl_rq->this_bw;
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lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock);
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dl_rq->this_bw -= dl_bw;
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SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */
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if (dl_rq->this_bw > old)
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dl_rq->this_bw = 0;
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SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
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}
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void dl_change_utilization(struct task_struct *p, u64 new_bw)
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{
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struct rq *rq;
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if (task_on_rq_queued(p))
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return;
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rq = task_rq(p);
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if (p->dl.dl_non_contending) {
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sub_running_bw(p->dl.dl_bw, &rq->dl);
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p->dl.dl_non_contending = 0;
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/*
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* If the timer handler is currently running and the
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* timer cannot be cancelled, inactive_task_timer()
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* will see that dl_not_contending is not set, and
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* will not touch the rq's active utilization,
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* so we are still safe.
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*/
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if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
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put_task_struct(p);
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}
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sub_rq_bw(p->dl.dl_bw, &rq->dl);
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add_rq_bw(new_bw, &rq->dl);
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}
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/*
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* The utilization of a task cannot be immediately removed from
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* the rq active utilization (running_bw) when the task blocks.
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* Instead, we have to wait for the so called "0-lag time".
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*
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* If a task blocks before the "0-lag time", a timer (the inactive
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* timer) is armed, and running_bw is decreased when the timer
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* fires.
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*
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* If the task wakes up again before the inactive timer fires,
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* the timer is cancelled, whereas if the task wakes up after the
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* inactive timer fired (and running_bw has been decreased) the
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* task's utilization has to be added to running_bw again.
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* A flag in the deadline scheduling entity (dl_non_contending)
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* is used to avoid race conditions between the inactive timer handler
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* and task wakeups.
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*
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* The following diagram shows how running_bw is updated. A task is
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* "ACTIVE" when its utilization contributes to running_bw; an
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* "ACTIVE contending" task is in the TASK_RUNNING state, while an
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* "ACTIVE non contending" task is a blocked task for which the "0-lag time"
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* has not passed yet. An "INACTIVE" task is a task for which the "0-lag"
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* time already passed, which does not contribute to running_bw anymore.
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* +------------------+
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* wakeup | ACTIVE |
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* +------------------>+ contending |
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* | add_running_bw | |
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* | +----+------+------+
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* | | ^
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* | dequeue | |
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* +--------+-------+ | |
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* | | t >= 0-lag | | wakeup
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* | INACTIVE |<---------------+ |
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* | | sub_running_bw | |
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* +--------+-------+ | |
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* ^ | |
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* | t < 0-lag | |
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* | | |
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* | V |
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* | +----+------+------+
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* | sub_running_bw | ACTIVE |
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* +-------------------+ |
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* inactive timer | non contending |
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* fired +------------------+
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*
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* The task_non_contending() function is invoked when a task
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* blocks, and checks if the 0-lag time already passed or
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* not (in the first case, it directly updates running_bw;
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* in the second case, it arms the inactive timer).
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*
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* The task_contending() function is invoked when a task wakes
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* up, and checks if the task is still in the "ACTIVE non contending"
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* state or not (in the second case, it updates running_bw).
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*/
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static void task_non_contending(struct task_struct *p)
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{
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struct sched_dl_entity *dl_se = &p->dl;
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struct hrtimer *timer = &dl_se->inactive_timer;
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struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
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struct rq *rq = rq_of_dl_rq(dl_rq);
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s64 zerolag_time;
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/*
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* If this is a non-deadline task that has been boosted,
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* do nothing
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*/
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if (dl_se->dl_runtime == 0)
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return;
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WARN_ON(hrtimer_active(&dl_se->inactive_timer));
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WARN_ON(dl_se->dl_non_contending);
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zerolag_time = dl_se->deadline -
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div64_long((dl_se->runtime * dl_se->dl_period),
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dl_se->dl_runtime);
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/*
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* Using relative times instead of the absolute "0-lag time"
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* allows to simplify the code
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*/
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zerolag_time -= rq_clock(rq);
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/*
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* If the "0-lag time" already passed, decrease the active
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* utilization now, instead of starting a timer
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*/
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if (zerolag_time < 0) {
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if (dl_task(p))
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sub_running_bw(dl_se->dl_bw, dl_rq);
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if (!dl_task(p) || p->state == TASK_DEAD) {
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struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
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if (p->state == TASK_DEAD)
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sub_rq_bw(p->dl.dl_bw, &rq->dl);
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raw_spin_lock(&dl_b->lock);
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__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
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__dl_clear_params(p);
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raw_spin_unlock(&dl_b->lock);
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}
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return;
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}
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dl_se->dl_non_contending = 1;
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get_task_struct(p);
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hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL);
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}
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static void task_contending(struct sched_dl_entity *dl_se, int flags)
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{
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struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
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/*
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* If this is a non-deadline task that has been boosted,
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* do nothing
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*/
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if (dl_se->dl_runtime == 0)
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return;
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if (flags & ENQUEUE_MIGRATED)
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add_rq_bw(dl_se->dl_bw, dl_rq);
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if (dl_se->dl_non_contending) {
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dl_se->dl_non_contending = 0;
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/*
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* If the timer handler is currently running and the
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* timer cannot be cancelled, inactive_task_timer()
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* will see that dl_not_contending is not set, and
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* will not touch the rq's active utilization,
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* so we are still safe.
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*/
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if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1)
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put_task_struct(dl_task_of(dl_se));
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} else {
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/*
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* Since "dl_non_contending" is not set, the
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* task's utilization has already been removed from
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* active utilization (either when the task blocked,
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* when the "inactive timer" fired).
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* So, add it back.
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*/
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add_running_bw(dl_se->dl_bw, dl_rq);
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}
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}
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static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
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{
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struct sched_dl_entity *dl_se = &p->dl;
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return dl_rq->root.rb_leftmost == &dl_se->rb_node;
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}
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void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
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{
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raw_spin_lock_init(&dl_b->dl_runtime_lock);
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dl_b->dl_period = period;
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dl_b->dl_runtime = runtime;
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}
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void init_dl_bw(struct dl_bw *dl_b)
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{
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raw_spin_lock_init(&dl_b->lock);
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raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock);
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if (global_rt_runtime() == RUNTIME_INF)
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dl_b->bw = -1;
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else
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dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
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raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock);
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dl_b->total_bw = 0;
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}
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void init_dl_rq(struct dl_rq *dl_rq)
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{
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dl_rq->root = RB_ROOT_CACHED;
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#ifdef CONFIG_SMP
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/* zero means no -deadline tasks */
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dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
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dl_rq->dl_nr_migratory = 0;
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dl_rq->overloaded = 0;
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dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED;
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#else
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init_dl_bw(&dl_rq->dl_bw);
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#endif
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dl_rq->running_bw = 0;
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dl_rq->this_bw = 0;
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init_dl_rq_bw_ratio(dl_rq);
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}
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#ifdef CONFIG_SMP
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static inline int dl_overloaded(struct rq *rq)
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{
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return atomic_read(&rq->rd->dlo_count);
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}
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static inline void dl_set_overload(struct rq *rq)
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{
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if (!rq->online)
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return;
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cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
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/*
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* Must be visible before the overload count is
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* set (as in sched_rt.c).
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*
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* Matched by the barrier in pull_dl_task().
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*/
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smp_wmb();
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atomic_inc(&rq->rd->dlo_count);
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}
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static inline void dl_clear_overload(struct rq *rq)
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{
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if (!rq->online)
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return;
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atomic_dec(&rq->rd->dlo_count);
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cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
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}
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static void update_dl_migration(struct dl_rq *dl_rq)
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{
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if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) {
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if (!dl_rq->overloaded) {
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dl_set_overload(rq_of_dl_rq(dl_rq));
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dl_rq->overloaded = 1;
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}
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} else if (dl_rq->overloaded) {
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dl_clear_overload(rq_of_dl_rq(dl_rq));
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dl_rq->overloaded = 0;
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}
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}
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static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
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{
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struct task_struct *p = dl_task_of(dl_se);
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if (p->nr_cpus_allowed > 1)
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dl_rq->dl_nr_migratory++;
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update_dl_migration(dl_rq);
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}
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static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
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{
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struct task_struct *p = dl_task_of(dl_se);
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if (p->nr_cpus_allowed > 1)
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dl_rq->dl_nr_migratory--;
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update_dl_migration(dl_rq);
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}
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/*
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* The list of pushable -deadline task is not a plist, like in
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* sched_rt.c, it is an rb-tree with tasks ordered by deadline.
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*/
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static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
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{
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struct dl_rq *dl_rq = &rq->dl;
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struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_root.rb_node;
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struct rb_node *parent = NULL;
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struct task_struct *entry;
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bool leftmost = true;
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BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
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while (*link) {
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parent = *link;
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entry = rb_entry(parent, struct task_struct,
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pushable_dl_tasks);
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if (dl_entity_preempt(&p->dl, &entry->dl))
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link = &parent->rb_left;
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else {
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link = &parent->rb_right;
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leftmost = false;
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}
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}
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if (leftmost)
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dl_rq->earliest_dl.next = p->dl.deadline;
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rb_link_node(&p->pushable_dl_tasks, parent, link);
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rb_insert_color_cached(&p->pushable_dl_tasks,
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&dl_rq->pushable_dl_tasks_root, leftmost);
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}
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static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
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{
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struct dl_rq *dl_rq = &rq->dl;
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if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
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return;
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if (dl_rq->pushable_dl_tasks_root.rb_leftmost == &p->pushable_dl_tasks) {
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struct rb_node *next_node;
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next_node = rb_next(&p->pushable_dl_tasks);
|
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if (next_node) {
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dl_rq->earliest_dl.next = rb_entry(next_node,
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struct task_struct, pushable_dl_tasks)->dl.deadline;
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}
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}
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rb_erase_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
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RB_CLEAR_NODE(&p->pushable_dl_tasks);
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}
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static inline int has_pushable_dl_tasks(struct rq *rq)
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{
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return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root);
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}
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|
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static int push_dl_task(struct rq *rq);
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|
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static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
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{
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|
return dl_task(prev);
|
|
}
|
|
|
|
static DEFINE_PER_CPU(struct callback_head, dl_push_head);
|
|
static DEFINE_PER_CPU(struct callback_head, dl_pull_head);
|
|
|
|
static void push_dl_tasks(struct rq *);
|
|
static void pull_dl_task(struct rq *);
|
|
|
|
static inline void 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 queue_pull_task(struct rq *rq)
|
|
{
|
|
queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task);
|
|
}
|
|
|
|
static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
|
|
|
|
static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct rq *later_rq = NULL;
|
|
|
|
later_rq = find_lock_later_rq(p, rq);
|
|
if (!later_rq) {
|
|
int cpu;
|
|
|
|
/*
|
|
* If we cannot preempt any rq, fall back to pick any
|
|
* online cpu.
|
|
*/
|
|
cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
|
|
if (cpu >= nr_cpu_ids) {
|
|
/*
|
|
* Fail to find any suitable cpu.
|
|
* The task will never come back!
|
|
*/
|
|
BUG_ON(dl_bandwidth_enabled());
|
|
|
|
/*
|
|
* If admission control is disabled we
|
|
* try a little harder to let the task
|
|
* run.
|
|
*/
|
|
cpu = cpumask_any(cpu_active_mask);
|
|
}
|
|
later_rq = cpu_rq(cpu);
|
|
double_lock_balance(rq, later_rq);
|
|
}
|
|
|
|
set_task_cpu(p, later_rq->cpu);
|
|
double_unlock_balance(later_rq, rq);
|
|
|
|
return later_rq;
|
|
}
|
|
|
|
#else
|
|
|
|
static inline
|
|
void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline
|
|
void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline
|
|
void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
|
|
{
|
|
}
|
|
|
|
static inline
|
|
void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
|
|
{
|
|
}
|
|
|
|
static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline void pull_dl_task(struct rq *rq)
|
|
{
|
|
}
|
|
|
|
static inline void queue_push_tasks(struct rq *rq)
|
|
{
|
|
}
|
|
|
|
static inline void queue_pull_task(struct rq *rq)
|
|
{
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
|
|
static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
|
|
static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
|
|
int flags);
|
|
|
|
/*
|
|
* We are being explicitly informed that a new instance is starting,
|
|
* and this means that:
|
|
* - the absolute deadline of the entity has to be placed at
|
|
* current time + relative deadline;
|
|
* - the runtime of the entity has to be set to the maximum value.
|
|
*
|
|
* The capability of specifying such event is useful whenever a -deadline
|
|
* entity wants to (try to!) synchronize its behaviour with the scheduler's
|
|
* one, and to (try to!) reconcile itself with its own scheduling
|
|
* parameters.
|
|
*/
|
|
static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
|
|
{
|
|
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
|
|
struct rq *rq = rq_of_dl_rq(dl_rq);
|
|
|
|
WARN_ON(dl_se->dl_boosted);
|
|
WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
|
|
|
|
/*
|
|
* We are racing with the deadline timer. So, do nothing because
|
|
* the deadline timer handler will take care of properly recharging
|
|
* the runtime and postponing the deadline
|
|
*/
|
|
if (dl_se->dl_throttled)
|
|
return;
|
|
|
|
/*
|
|
* We use the regular wall clock time to set deadlines in the
|
|
* future; in fact, we must consider execution overheads (time
|
|
* spent on hardirq context, etc.).
|
|
*/
|
|
dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline;
|
|
dl_se->runtime = dl_se->dl_runtime;
|
|
}
|
|
|
|
/*
|
|
* Pure Earliest Deadline First (EDF) scheduling does not deal with the
|
|
* possibility of a entity lasting more than what it declared, and thus
|
|
* exhausting its runtime.
|
|
*
|
|
* Here we are interested in making runtime overrun possible, but we do
|
|
* not want a entity which is misbehaving to affect the scheduling of all
|
|
* other entities.
|
|
* Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
|
|
* is used, in order to confine each entity within its own bandwidth.
|
|
*
|
|
* This function deals exactly with that, and ensures that when the runtime
|
|
* of a entity is replenished, its deadline is also postponed. That ensures
|
|
* the overrunning entity can't interfere with other entity in the system and
|
|
* can't make them miss their deadlines. Reasons why this kind of overruns
|
|
* could happen are, typically, a entity voluntarily trying to overcome its
|
|
* runtime, or it just underestimated it during sched_setattr().
|
|
*/
|
|
static void replenish_dl_entity(struct sched_dl_entity *dl_se,
|
|
struct sched_dl_entity *pi_se)
|
|
{
|
|
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
|
|
struct rq *rq = rq_of_dl_rq(dl_rq);
|
|
|
|
BUG_ON(pi_se->dl_runtime <= 0);
|
|
|
|
/*
|
|
* This could be the case for a !-dl task that is boosted.
|
|
* Just go with full inherited parameters.
|
|
*/
|
|
if (dl_se->dl_deadline == 0) {
|
|
dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
|
|
dl_se->runtime = pi_se->dl_runtime;
|
|
}
|
|
|
|
if (dl_se->dl_yielded && dl_se->runtime > 0)
|
|
dl_se->runtime = 0;
|
|
|
|
/*
|
|
* We keep moving the deadline away until we get some
|
|
* available runtime for the entity. This ensures correct
|
|
* handling of situations where the runtime overrun is
|
|
* arbitrary large.
|
|
*/
|
|
while (dl_se->runtime <= 0) {
|
|
dl_se->deadline += pi_se->dl_period;
|
|
dl_se->runtime += pi_se->dl_runtime;
|
|
}
|
|
|
|
/*
|
|
* At this point, the deadline really should be "in
|
|
* the future" with respect to rq->clock. If it's
|
|
* not, we are, for some reason, lagging too much!
|
|
* Anyway, after having warn userspace abut that,
|
|
* we still try to keep the things running by
|
|
* resetting the deadline and the budget of the
|
|
* entity.
|
|
*/
|
|
if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
|
|
printk_deferred_once("sched: DL replenish lagged too much\n");
|
|
dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
|
|
dl_se->runtime = pi_se->dl_runtime;
|
|
}
|
|
|
|
if (dl_se->dl_yielded)
|
|
dl_se->dl_yielded = 0;
|
|
if (dl_se->dl_throttled)
|
|
dl_se->dl_throttled = 0;
|
|
}
|
|
|
|
/*
|
|
* Here we check if --at time t-- an entity (which is probably being
|
|
* [re]activated or, in general, enqueued) can use its remaining runtime
|
|
* and its current deadline _without_ exceeding the bandwidth it is
|
|
* assigned (function returns true if it can't). We are in fact applying
|
|
* one of the CBS rules: when a task wakes up, if the residual runtime
|
|
* over residual deadline fits within the allocated bandwidth, then we
|
|
* can keep the current (absolute) deadline and residual budget without
|
|
* disrupting the schedulability of the system. Otherwise, we should
|
|
* refill the runtime and set the deadline a period in the future,
|
|
* because keeping the current (absolute) deadline of the task would
|
|
* result in breaking guarantees promised to other tasks (refer to
|
|
* Documentation/scheduler/sched-deadline.txt for more informations).
|
|
*
|
|
* This function returns true if:
|
|
*
|
|
* runtime / (deadline - t) > dl_runtime / dl_deadline ,
|
|
*
|
|
* IOW we can't recycle current parameters.
|
|
*
|
|
* Notice that the bandwidth check is done against the deadline. For
|
|
* task with deadline equal to period this is the same of using
|
|
* dl_period instead of dl_deadline in the equation above.
|
|
*/
|
|
static bool dl_entity_overflow(struct sched_dl_entity *dl_se,
|
|
struct sched_dl_entity *pi_se, u64 t)
|
|
{
|
|
u64 left, right;
|
|
|
|
/*
|
|
* left and right are the two sides of the equation above,
|
|
* after a bit of shuffling to use multiplications instead
|
|
* of divisions.
|
|
*
|
|
* Note that none of the time values involved in the two
|
|
* multiplications are absolute: dl_deadline and dl_runtime
|
|
* are the relative deadline and the maximum runtime of each
|
|
* instance, runtime is the runtime left for the last instance
|
|
* and (deadline - t), since t is rq->clock, is the time left
|
|
* to the (absolute) deadline. Even if overflowing the u64 type
|
|
* is very unlikely to occur in both cases, here we scale down
|
|
* as we want to avoid that risk at all. Scaling down by 10
|
|
* means that we reduce granularity to 1us. We are fine with it,
|
|
* since this is only a true/false check and, anyway, thinking
|
|
* of anything below microseconds resolution is actually fiction
|
|
* (but still we want to give the user that illusion >;).
|
|
*/
|
|
left = (pi_se->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
|
|
right = ((dl_se->deadline - t) >> DL_SCALE) *
|
|
(pi_se->dl_runtime >> DL_SCALE);
|
|
|
|
return dl_time_before(right, left);
|
|
}
|
|
|
|
/*
|
|
* Revised wakeup rule [1]: For self-suspending tasks, rather then
|
|
* re-initializing task's runtime and deadline, the revised wakeup
|
|
* rule adjusts the task's runtime to avoid the task to overrun its
|
|
* density.
|
|
*
|
|
* Reasoning: a task may overrun the density if:
|
|
* runtime / (deadline - t) > dl_runtime / dl_deadline
|
|
*
|
|
* Therefore, runtime can be adjusted to:
|
|
* runtime = (dl_runtime / dl_deadline) * (deadline - t)
|
|
*
|
|
* In such way that runtime will be equal to the maximum density
|
|
* the task can use without breaking any rule.
|
|
*
|
|
* [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant
|
|
* bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24.
|
|
*/
|
|
static void
|
|
update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq)
|
|
{
|
|
u64 laxity = dl_se->deadline - rq_clock(rq);
|
|
|
|
/*
|
|
* If the task has deadline < period, and the deadline is in the past,
|
|
* it should already be throttled before this check.
|
|
*
|
|
* See update_dl_entity() comments for further details.
|
|
*/
|
|
WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq)));
|
|
|
|
dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT;
|
|
}
|
|
|
|
/*
|
|
* Regarding the deadline, a task with implicit deadline has a relative
|
|
* deadline == relative period. A task with constrained deadline has a
|
|
* relative deadline <= relative period.
|
|
*
|
|
* We support constrained deadline tasks. However, there are some restrictions
|
|
* applied only for tasks which do not have an implicit deadline. See
|
|
* update_dl_entity() to know more about such restrictions.
|
|
*
|
|
* The dl_is_implicit() returns true if the task has an implicit deadline.
|
|
*/
|
|
static inline bool dl_is_implicit(struct sched_dl_entity *dl_se)
|
|
{
|
|
return dl_se->dl_deadline == dl_se->dl_period;
|
|
}
|
|
|
|
/*
|
|
* When a deadline entity is placed in the runqueue, its runtime and deadline
|
|
* might need to be updated. This is done by a CBS wake up rule. There are two
|
|
* different rules: 1) the original CBS; and 2) the Revisited CBS.
|
|
*
|
|
* When the task is starting a new period, the Original CBS is used. In this
|
|
* case, the runtime is replenished and a new absolute deadline is set.
|
|
*
|
|
* When a task is queued before the begin of the next period, using the
|
|
* remaining runtime and deadline could make the entity to overflow, see
|
|
* dl_entity_overflow() to find more about runtime overflow. When such case
|
|
* is detected, the runtime and deadline need to be updated.
|
|
*
|
|
* If the task has an implicit deadline, i.e., deadline == period, the Original
|
|
* CBS is applied. the runtime is replenished and a new absolute deadline is
|
|
* set, as in the previous cases.
|
|
*
|
|
* However, the Original CBS does not work properly for tasks with
|
|
* deadline < period, which are said to have a constrained deadline. By
|
|
* applying the Original CBS, a constrained deadline task would be able to run
|
|
* runtime/deadline in a period. With deadline < period, the task would
|
|
* overrun the runtime/period allowed bandwidth, breaking the admission test.
|
|
*
|
|
* In order to prevent this misbehave, the Revisited CBS is used for
|
|
* constrained deadline tasks when a runtime overflow is detected. In the
|
|
* Revisited CBS, rather than replenishing & setting a new absolute deadline,
|
|
* the remaining runtime of the task is reduced to avoid runtime overflow.
|
|
* Please refer to the comments update_dl_revised_wakeup() function to find
|
|
* more about the Revised CBS rule.
|
|
*/
|
|
static void update_dl_entity(struct sched_dl_entity *dl_se,
|
|
struct sched_dl_entity *pi_se)
|
|
{
|
|
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
|
|
struct rq *rq = rq_of_dl_rq(dl_rq);
|
|
|
|
if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
|
|
dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) {
|
|
|
|
if (unlikely(!dl_is_implicit(dl_se) &&
|
|
!dl_time_before(dl_se->deadline, rq_clock(rq)) &&
|
|
!dl_se->dl_boosted)){
|
|
update_dl_revised_wakeup(dl_se, rq);
|
|
return;
|
|
}
|
|
|
|
dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
|
|
dl_se->runtime = pi_se->dl_runtime;
|
|
}
|
|
}
|
|
|
|
static inline u64 dl_next_period(struct sched_dl_entity *dl_se)
|
|
{
|
|
return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period;
|
|
}
|
|
|
|
/*
|
|
* If the entity depleted all its runtime, and if we want it to sleep
|
|
* while waiting for some new execution time to become available, we
|
|
* set the bandwidth replenishment timer to the replenishment instant
|
|
* and try to activate it.
|
|
*
|
|
* Notice that it is important for the caller to know if the timer
|
|
* actually started or not (i.e., the replenishment instant is in
|
|
* the future or in the past).
|
|
*/
|
|
static int start_dl_timer(struct task_struct *p)
|
|
{
|
|
struct sched_dl_entity *dl_se = &p->dl;
|
|
struct hrtimer *timer = &dl_se->dl_timer;
|
|
struct rq *rq = task_rq(p);
|
|
ktime_t now, act;
|
|
s64 delta;
|
|
|
|
lockdep_assert_held(&rq->lock);
|
|
|
|
/*
|
|
* We want the timer to fire at the deadline, but considering
|
|
* that it is actually coming from rq->clock and not from
|
|
* hrtimer's time base reading.
|
|
*/
|
|
act = ns_to_ktime(dl_next_period(dl_se));
|
|
now = hrtimer_cb_get_time(timer);
|
|
delta = ktime_to_ns(now) - rq_clock(rq);
|
|
act = ktime_add_ns(act, delta);
|
|
|
|
/*
|
|
* If the expiry time already passed, e.g., because the value
|
|
* chosen as the deadline is too small, don't even try to
|
|
* start the timer in the past!
|
|
*/
|
|
if (ktime_us_delta(act, now) < 0)
|
|
return 0;
|
|
|
|
/*
|
|
* !enqueued will guarantee another callback; even if one is already in
|
|
* progress. This ensures a balanced {get,put}_task_struct().
|
|
*
|
|
* The race against __run_timer() clearing the enqueued state is
|
|
* harmless because we're holding task_rq()->lock, therefore the timer
|
|
* expiring after we've done the check will wait on its task_rq_lock()
|
|
* and observe our state.
|
|
*/
|
|
if (!hrtimer_is_queued(timer)) {
|
|
get_task_struct(p);
|
|
hrtimer_start(timer, act, HRTIMER_MODE_ABS);
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* This is the bandwidth enforcement timer callback. If here, we know
|
|
* a task is not on its dl_rq, since the fact that the timer was running
|
|
* means the task is throttled and needs a runtime replenishment.
|
|
*
|
|
* However, what we actually do depends on the fact the task is active,
|
|
* (it is on its rq) or has been removed from there by a call to
|
|
* dequeue_task_dl(). In the former case we must issue the runtime
|
|
* replenishment and add the task back to the dl_rq; in the latter, we just
|
|
* do nothing but clearing dl_throttled, so that runtime and deadline
|
|
* updating (and the queueing back to dl_rq) will be done by the
|
|
* next call to enqueue_task_dl().
|
|
*/
|
|
static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
|
|
{
|
|
struct sched_dl_entity *dl_se = container_of(timer,
|
|
struct sched_dl_entity,
|
|
dl_timer);
|
|
struct task_struct *p = dl_task_of(dl_se);
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
rq = task_rq_lock(p, &rf);
|
|
|
|
/*
|
|
* The task might have changed its scheduling policy to something
|
|
* different than SCHED_DEADLINE (through switched_from_dl()).
|
|
*/
|
|
if (!dl_task(p))
|
|
goto unlock;
|
|
|
|
/*
|
|
* The task might have been boosted by someone else and might be in the
|
|
* boosting/deboosting path, its not throttled.
|
|
*/
|
|
if (dl_se->dl_boosted)
|
|
goto unlock;
|
|
|
|
/*
|
|
* Spurious timer due to start_dl_timer() race; or we already received
|
|
* a replenishment from rt_mutex_setprio().
|
|
*/
|
|
if (!dl_se->dl_throttled)
|
|
goto unlock;
|
|
|
|
sched_clock_tick();
|
|
update_rq_clock(rq);
|
|
|
|
/*
|
|
* If the throttle happened during sched-out; like:
|
|
*
|
|
* schedule()
|
|
* deactivate_task()
|
|
* dequeue_task_dl()
|
|
* update_curr_dl()
|
|
* start_dl_timer()
|
|
* __dequeue_task_dl()
|
|
* prev->on_rq = 0;
|
|
*
|
|
* We can be both throttled and !queued. Replenish the counter
|
|
* but do not enqueue -- wait for our wakeup to do that.
|
|
*/
|
|
if (!task_on_rq_queued(p)) {
|
|
replenish_dl_entity(dl_se, dl_se);
|
|
goto unlock;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (unlikely(!rq->online)) {
|
|
/*
|
|
* If the runqueue is no longer available, migrate the
|
|
* task elsewhere. This necessarily changes rq.
|
|
*/
|
|
lockdep_unpin_lock(&rq->lock, rf.cookie);
|
|
rq = dl_task_offline_migration(rq, p);
|
|
rf.cookie = lockdep_pin_lock(&rq->lock);
|
|
update_rq_clock(rq);
|
|
|
|
/*
|
|
* Now that the task has been migrated to the new RQ and we
|
|
* have that locked, proceed as normal and enqueue the task
|
|
* there.
|
|
*/
|
|
}
|
|
#endif
|
|
|
|
enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
|
|
if (dl_task(rq->curr))
|
|
check_preempt_curr_dl(rq, p, 0);
|
|
else
|
|
resched_curr(rq);
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* Queueing this task back might have overloaded rq, check if we need
|
|
* to kick someone away.
|
|
*/
|
|
if (has_pushable_dl_tasks(rq)) {
|
|
/*
|
|
* Nothing relies on rq->lock after this, so its safe to drop
|
|
* rq->lock.
|
|
*/
|
|
rq_unpin_lock(rq, &rf);
|
|
push_dl_task(rq);
|
|
rq_repin_lock(rq, &rf);
|
|
}
|
|
#endif
|
|
|
|
unlock:
|
|
task_rq_unlock(rq, p, &rf);
|
|
|
|
/*
|
|
* This can free the task_struct, including this hrtimer, do not touch
|
|
* anything related to that after this.
|
|
*/
|
|
put_task_struct(p);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
void init_dl_task_timer(struct sched_dl_entity *dl_se)
|
|
{
|
|
struct hrtimer *timer = &dl_se->dl_timer;
|
|
|
|
hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
timer->function = dl_task_timer;
|
|
}
|
|
|
|
/*
|
|
* During the activation, CBS checks if it can reuse the current task's
|
|
* runtime and period. If the deadline of the task is in the past, CBS
|
|
* cannot use the runtime, and so it replenishes the task. This rule
|
|
* works fine for implicit deadline tasks (deadline == period), and the
|
|
* CBS was designed for implicit deadline tasks. However, a task with
|
|
* constrained deadline (deadine < period) might be awakened after the
|
|
* deadline, but before the next period. In this case, replenishing the
|
|
* task would allow it to run for runtime / deadline. As in this case
|
|
* deadline < period, CBS enables a task to run for more than the
|
|
* runtime / period. In a very loaded system, this can cause a domino
|
|
* effect, making other tasks miss their deadlines.
|
|
*
|
|
* To avoid this problem, in the activation of a constrained deadline
|
|
* task after the deadline but before the next period, throttle the
|
|
* task and set the replenishing timer to the begin of the next period,
|
|
* unless it is boosted.
|
|
*/
|
|
static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
|
|
{
|
|
struct task_struct *p = dl_task_of(dl_se);
|
|
struct rq *rq = rq_of_dl_rq(dl_rq_of_se(dl_se));
|
|
|
|
if (dl_time_before(dl_se->deadline, rq_clock(rq)) &&
|
|
dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
|
|
if (unlikely(dl_se->dl_boosted || !start_dl_timer(p)))
|
|
return;
|
|
dl_se->dl_throttled = 1;
|
|
if (dl_se->runtime > 0)
|
|
dl_se->runtime = 0;
|
|
}
|
|
}
|
|
|
|
static
|
|
int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
|
|
{
|
|
return (dl_se->runtime <= 0);
|
|
}
|
|
|
|
extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
|
|
|
|
/*
|
|
* This function implements the GRUB accounting rule:
|
|
* according to the GRUB reclaiming algorithm, the runtime is
|
|
* not decreased as "dq = -dt", but as
|
|
* "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt",
|
|
* where u is the utilization of the task, Umax is the maximum reclaimable
|
|
* utilization, Uinact is the (per-runqueue) inactive utilization, computed
|
|
* as the difference between the "total runqueue utilization" and the
|
|
* runqueue active utilization, and Uextra is the (per runqueue) extra
|
|
* reclaimable utilization.
|
|
* Since rq->dl.running_bw and rq->dl.this_bw contain utilizations
|
|
* multiplied by 2^BW_SHIFT, the result has to be shifted right by
|
|
* BW_SHIFT.
|
|
* Since rq->dl.bw_ratio contains 1 / Umax multipled by 2^RATIO_SHIFT,
|
|
* dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
|
|
* Since delta is a 64 bit variable, to have an overflow its value
|
|
* should be larger than 2^(64 - 20 - 8), which is more than 64 seconds.
|
|
* So, overflow is not an issue here.
|
|
*/
|
|
u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se)
|
|
{
|
|
u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */
|
|
u64 u_act;
|
|
u64 u_act_min = (dl_se->dl_bw * rq->dl.bw_ratio) >> RATIO_SHIFT;
|
|
|
|
/*
|
|
* Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)},
|
|
* we compare u_inact + rq->dl.extra_bw with
|
|
* 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because
|
|
* u_inact + rq->dl.extra_bw can be larger than
|
|
* 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative
|
|
* leading to wrong results)
|
|
*/
|
|
if (u_inact + rq->dl.extra_bw > BW_UNIT - u_act_min)
|
|
u_act = u_act_min;
|
|
else
|
|
u_act = BW_UNIT - u_inact - rq->dl.extra_bw;
|
|
|
|
return (delta * u_act) >> BW_SHIFT;
|
|
}
|
|
|
|
/*
|
|
* Update the current task's runtime statistics (provided it is still
|
|
* a -deadline task and has not been removed from the dl_rq).
|
|
*/
|
|
static void update_curr_dl(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct sched_dl_entity *dl_se = &curr->dl;
|
|
u64 delta_exec;
|
|
|
|
if (!dl_task(curr) || !on_dl_rq(dl_se))
|
|
return;
|
|
|
|
/*
|
|
* Consumed budget is computed considering the time as
|
|
* observed by schedulable tasks (excluding time spent
|
|
* in hardirq context, etc.). Deadlines are instead
|
|
* computed using hard walltime. This seems to be the more
|
|
* natural solution, but the full ramifications of this
|
|
* approach need further study.
|
|
*/
|
|
delta_exec = rq_clock_task(rq) - curr->se.exec_start;
|
|
if (unlikely((s64)delta_exec <= 0)) {
|
|
if (unlikely(dl_se->dl_yielded))
|
|
goto throttle;
|
|
return;
|
|
}
|
|
|
|
/* kick cpufreq (see the comment in kernel/sched/sched.h). */
|
|
cpufreq_update_util(rq, SCHED_CPUFREQ_DL);
|
|
|
|
schedstat_set(curr->se.statistics.exec_max,
|
|
max(curr->se.statistics.exec_max, delta_exec));
|
|
|
|
curr->se.sum_exec_runtime += delta_exec;
|
|
account_group_exec_runtime(curr, delta_exec);
|
|
|
|
curr->se.exec_start = rq_clock_task(rq);
|
|
cgroup_account_cputime(curr, delta_exec);
|
|
|
|
sched_rt_avg_update(rq, delta_exec);
|
|
|
|
if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM))
|
|
delta_exec = grub_reclaim(delta_exec, rq, &curr->dl);
|
|
dl_se->runtime -= delta_exec;
|
|
|
|
throttle:
|
|
if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
|
|
dl_se->dl_throttled = 1;
|
|
__dequeue_task_dl(rq, curr, 0);
|
|
if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr)))
|
|
enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
|
|
|
|
if (!is_leftmost(curr, &rq->dl))
|
|
resched_curr(rq);
|
|
}
|
|
|
|
/*
|
|
* Because -- for now -- we share the rt bandwidth, we need to
|
|
* account our runtime there too, otherwise actual rt tasks
|
|
* would be able to exceed the shared quota.
|
|
*
|
|
* Account to the root rt group for now.
|
|
*
|
|
* The solution we're working towards is having the RT groups scheduled
|
|
* using deadline servers -- however there's a few nasties to figure
|
|
* out before that can happen.
|
|
*/
|
|
if (rt_bandwidth_enabled()) {
|
|
struct rt_rq *rt_rq = &rq->rt;
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
/*
|
|
* We'll let actual RT tasks worry about the overflow here, we
|
|
* have our own CBS to keep us inline; only account when RT
|
|
* bandwidth is relevant.
|
|
*/
|
|
if (sched_rt_bandwidth_account(rt_rq))
|
|
rt_rq->rt_time += delta_exec;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
}
|
|
|
|
static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
|
|
{
|
|
struct sched_dl_entity *dl_se = container_of(timer,
|
|
struct sched_dl_entity,
|
|
inactive_timer);
|
|
struct task_struct *p = dl_task_of(dl_se);
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
rq = task_rq_lock(p, &rf);
|
|
|
|
if (!dl_task(p) || p->state == TASK_DEAD) {
|
|
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
|
|
|
|
if (p->state == TASK_DEAD && dl_se->dl_non_contending) {
|
|
sub_running_bw(p->dl.dl_bw, dl_rq_of_se(&p->dl));
|
|
sub_rq_bw(p->dl.dl_bw, dl_rq_of_se(&p->dl));
|
|
dl_se->dl_non_contending = 0;
|
|
}
|
|
|
|
raw_spin_lock(&dl_b->lock);
|
|
__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
|
|
raw_spin_unlock(&dl_b->lock);
|
|
__dl_clear_params(p);
|
|
|
|
goto unlock;
|
|
}
|
|
if (dl_se->dl_non_contending == 0)
|
|
goto unlock;
|
|
|
|
sched_clock_tick();
|
|
update_rq_clock(rq);
|
|
|
|
sub_running_bw(dl_se->dl_bw, &rq->dl);
|
|
dl_se->dl_non_contending = 0;
|
|
unlock:
|
|
task_rq_unlock(rq, p, &rf);
|
|
put_task_struct(p);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se)
|
|
{
|
|
struct hrtimer *timer = &dl_se->inactive_timer;
|
|
|
|
hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
timer->function = inactive_task_timer;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
|
|
{
|
|
struct rq *rq = rq_of_dl_rq(dl_rq);
|
|
|
|
if (dl_rq->earliest_dl.curr == 0 ||
|
|
dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
|
|
dl_rq->earliest_dl.curr = deadline;
|
|
cpudl_set(&rq->rd->cpudl, rq->cpu, deadline);
|
|
}
|
|
}
|
|
|
|
static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
|
|
{
|
|
struct rq *rq = rq_of_dl_rq(dl_rq);
|
|
|
|
/*
|
|
* Since we may have removed our earliest (and/or next earliest)
|
|
* task we must recompute them.
|
|
*/
|
|
if (!dl_rq->dl_nr_running) {
|
|
dl_rq->earliest_dl.curr = 0;
|
|
dl_rq->earliest_dl.next = 0;
|
|
cpudl_clear(&rq->rd->cpudl, rq->cpu);
|
|
} else {
|
|
struct rb_node *leftmost = dl_rq->root.rb_leftmost;
|
|
struct sched_dl_entity *entry;
|
|
|
|
entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
|
|
dl_rq->earliest_dl.curr = entry->deadline;
|
|
cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
|
|
}
|
|
}
|
|
|
|
#else
|
|
|
|
static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
|
|
static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static inline
|
|
void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
|
|
{
|
|
int prio = dl_task_of(dl_se)->prio;
|
|
u64 deadline = dl_se->deadline;
|
|
|
|
WARN_ON(!dl_prio(prio));
|
|
dl_rq->dl_nr_running++;
|
|
add_nr_running(rq_of_dl_rq(dl_rq), 1);
|
|
|
|
inc_dl_deadline(dl_rq, deadline);
|
|
inc_dl_migration(dl_se, dl_rq);
|
|
}
|
|
|
|
static inline
|
|
void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
|
|
{
|
|
int prio = dl_task_of(dl_se)->prio;
|
|
|
|
WARN_ON(!dl_prio(prio));
|
|
WARN_ON(!dl_rq->dl_nr_running);
|
|
dl_rq->dl_nr_running--;
|
|
sub_nr_running(rq_of_dl_rq(dl_rq), 1);
|
|
|
|
dec_dl_deadline(dl_rq, dl_se->deadline);
|
|
dec_dl_migration(dl_se, dl_rq);
|
|
}
|
|
|
|
static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
|
|
{
|
|
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
|
|
struct rb_node **link = &dl_rq->root.rb_root.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct sched_dl_entity *entry;
|
|
int leftmost = 1;
|
|
|
|
BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
|
|
|
|
while (*link) {
|
|
parent = *link;
|
|
entry = rb_entry(parent, struct sched_dl_entity, rb_node);
|
|
if (dl_time_before(dl_se->deadline, entry->deadline))
|
|
link = &parent->rb_left;
|
|
else {
|
|
link = &parent->rb_right;
|
|
leftmost = 0;
|
|
}
|
|
}
|
|
|
|
rb_link_node(&dl_se->rb_node, parent, link);
|
|
rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost);
|
|
|
|
inc_dl_tasks(dl_se, dl_rq);
|
|
}
|
|
|
|
static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
|
|
{
|
|
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
|
|
|
|
if (RB_EMPTY_NODE(&dl_se->rb_node))
|
|
return;
|
|
|
|
rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
|
|
RB_CLEAR_NODE(&dl_se->rb_node);
|
|
|
|
dec_dl_tasks(dl_se, dl_rq);
|
|
}
|
|
|
|
static void
|
|
enqueue_dl_entity(struct sched_dl_entity *dl_se,
|
|
struct sched_dl_entity *pi_se, int flags)
|
|
{
|
|
BUG_ON(on_dl_rq(dl_se));
|
|
|
|
/*
|
|
* If this is a wakeup or a new instance, the scheduling
|
|
* parameters of the task might need updating. Otherwise,
|
|
* we want a replenishment of its runtime.
|
|
*/
|
|
if (flags & ENQUEUE_WAKEUP) {
|
|
task_contending(dl_se, flags);
|
|
update_dl_entity(dl_se, pi_se);
|
|
} else if (flags & ENQUEUE_REPLENISH) {
|
|
replenish_dl_entity(dl_se, pi_se);
|
|
} else if ((flags & ENQUEUE_RESTORE) &&
|
|
dl_time_before(dl_se->deadline,
|
|
rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) {
|
|
setup_new_dl_entity(dl_se);
|
|
}
|
|
|
|
__enqueue_dl_entity(dl_se);
|
|
}
|
|
|
|
static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
|
|
{
|
|
__dequeue_dl_entity(dl_se);
|
|
}
|
|
|
|
static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct task_struct *pi_task = rt_mutex_get_top_task(p);
|
|
struct sched_dl_entity *pi_se = &p->dl;
|
|
|
|
/*
|
|
* Use the scheduling parameters of the top pi-waiter task if:
|
|
* - we have a top pi-waiter which is a SCHED_DEADLINE task AND
|
|
* - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is
|
|
* smaller than our deadline OR we are a !SCHED_DEADLINE task getting
|
|
* boosted due to a SCHED_DEADLINE pi-waiter).
|
|
* Otherwise we keep our runtime and deadline.
|
|
*/
|
|
if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) {
|
|
pi_se = &pi_task->dl;
|
|
} else if (!dl_prio(p->normal_prio)) {
|
|
/*
|
|
* Special case in which we have a !SCHED_DEADLINE task
|
|
* that is going to be deboosted, but exceeds its
|
|
* runtime while doing so. No point in replenishing
|
|
* it, as it's going to return back to its original
|
|
* scheduling class after this.
|
|
*/
|
|
BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check if a constrained deadline task was activated
|
|
* after the deadline but before the next period.
|
|
* If that is the case, the task will be throttled and
|
|
* the replenishment timer will be set to the next period.
|
|
*/
|
|
if (!p->dl.dl_throttled && !dl_is_implicit(&p->dl))
|
|
dl_check_constrained_dl(&p->dl);
|
|
|
|
if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) {
|
|
add_rq_bw(p->dl.dl_bw, &rq->dl);
|
|
add_running_bw(p->dl.dl_bw, &rq->dl);
|
|
}
|
|
|
|
/*
|
|
* If p is throttled, we do not enqueue it. In fact, if it exhausted
|
|
* its budget it needs a replenishment and, since it now is on
|
|
* its rq, the bandwidth timer callback (which clearly has not
|
|
* run yet) will take care of this.
|
|
* However, the active utilization does not depend on the fact
|
|
* that the task is on the runqueue or not (but depends on the
|
|
* task's state - in GRUB parlance, "inactive" vs "active contending").
|
|
* In other words, even if a task is throttled its utilization must
|
|
* be counted in the active utilization; hence, we need to call
|
|
* add_running_bw().
|
|
*/
|
|
if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) {
|
|
if (flags & ENQUEUE_WAKEUP)
|
|
task_contending(&p->dl, flags);
|
|
|
|
return;
|
|
}
|
|
|
|
enqueue_dl_entity(&p->dl, pi_se, flags);
|
|
|
|
if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
|
|
enqueue_pushable_dl_task(rq, p);
|
|
}
|
|
|
|
static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
dequeue_dl_entity(&p->dl);
|
|
dequeue_pushable_dl_task(rq, p);
|
|
}
|
|
|
|
static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
update_curr_dl(rq);
|
|
__dequeue_task_dl(rq, p, flags);
|
|
|
|
if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) {
|
|
sub_running_bw(p->dl.dl_bw, &rq->dl);
|
|
sub_rq_bw(p->dl.dl_bw, &rq->dl);
|
|
}
|
|
|
|
/*
|
|
* This check allows to start the inactive timer (or to immediately
|
|
* decrease the active utilization, if needed) in two cases:
|
|
* when the task blocks and when it is terminating
|
|
* (p->state == TASK_DEAD). We can handle the two cases in the same
|
|
* way, because from GRUB's point of view the same thing is happening
|
|
* (the task moves from "active contending" to "active non contending"
|
|
* or "inactive")
|
|
*/
|
|
if (flags & DEQUEUE_SLEEP)
|
|
task_non_contending(p);
|
|
}
|
|
|
|
/*
|
|
* Yield task semantic for -deadline tasks is:
|
|
*
|
|
* get off from the CPU until our next instance, with
|
|
* a new runtime. This is of little use now, since we
|
|
* don't have a bandwidth reclaiming mechanism. Anyway,
|
|
* bandwidth reclaiming is planned for the future, and
|
|
* yield_task_dl will indicate that some spare budget
|
|
* is available for other task instances to use it.
|
|
*/
|
|
static void yield_task_dl(struct rq *rq)
|
|
{
|
|
/*
|
|
* We make the task go to sleep until its current deadline by
|
|
* forcing its runtime to zero. This way, update_curr_dl() stops
|
|
* it and the bandwidth timer will wake it up and will give it
|
|
* new scheduling parameters (thanks to dl_yielded=1).
|
|
*/
|
|
rq->curr->dl.dl_yielded = 1;
|
|
|
|
update_rq_clock(rq);
|
|
update_curr_dl(rq);
|
|
/*
|
|
* Tell update_rq_clock() that we've just updated,
|
|
* so we don't do microscopic update in schedule()
|
|
* and double the fastpath cost.
|
|
*/
|
|
rq_clock_skip_update(rq, true);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
static int find_later_rq(struct task_struct *task);
|
|
|
|
static int
|
|
select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
|
|
{
|
|
struct task_struct *curr;
|
|
struct rq *rq;
|
|
|
|
if (sd_flag != SD_BALANCE_WAKE)
|
|
goto out;
|
|
|
|
rq = cpu_rq(cpu);
|
|
|
|
rcu_read_lock();
|
|
curr = READ_ONCE(rq->curr); /* unlocked access */
|
|
|
|
/*
|
|
* If we are dealing with a -deadline task, we must
|
|
* decide where to wake it up.
|
|
* If it has a later deadline and the current task
|
|
* on this rq can't move (provided the waking task
|
|
* can!) we prefer to send it somewhere else. On the
|
|
* other hand, if it has a shorter deadline, we
|
|
* try to make it stay here, it might be important.
|
|
*/
|
|
if (unlikely(dl_task(curr)) &&
|
|
(curr->nr_cpus_allowed < 2 ||
|
|
!dl_entity_preempt(&p->dl, &curr->dl)) &&
|
|
(p->nr_cpus_allowed > 1)) {
|
|
int target = find_later_rq(p);
|
|
|
|
if (target != -1 &&
|
|
(dl_time_before(p->dl.deadline,
|
|
cpu_rq(target)->dl.earliest_dl.curr) ||
|
|
(cpu_rq(target)->dl.dl_nr_running == 0)))
|
|
cpu = target;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
out:
|
|
return cpu;
|
|
}
|
|
|
|
static void migrate_task_rq_dl(struct task_struct *p)
|
|
{
|
|
struct rq *rq;
|
|
|
|
if (p->state != TASK_WAKING)
|
|
return;
|
|
|
|
rq = task_rq(p);
|
|
/*
|
|
* Since p->state == TASK_WAKING, set_task_cpu() has been called
|
|
* from try_to_wake_up(). Hence, p->pi_lock is locked, but
|
|
* rq->lock is not... So, lock it
|
|
*/
|
|
raw_spin_lock(&rq->lock);
|
|
if (p->dl.dl_non_contending) {
|
|
sub_running_bw(p->dl.dl_bw, &rq->dl);
|
|
p->dl.dl_non_contending = 0;
|
|
/*
|
|
* If the timer handler is currently running and the
|
|
* timer cannot be cancelled, inactive_task_timer()
|
|
* will see that dl_not_contending is not set, and
|
|
* will not touch the rq's active utilization,
|
|
* so we are still safe.
|
|
*/
|
|
if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
|
|
put_task_struct(p);
|
|
}
|
|
sub_rq_bw(p->dl.dl_bw, &rq->dl);
|
|
raw_spin_unlock(&rq->lock);
|
|
}
|
|
|
|
static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* Current can't be migrated, useless to reschedule,
|
|
* let's hope p can move out.
|
|
*/
|
|
if (rq->curr->nr_cpus_allowed == 1 ||
|
|
!cpudl_find(&rq->rd->cpudl, rq->curr, NULL))
|
|
return;
|
|
|
|
/*
|
|
* p is migratable, so let's not schedule it and
|
|
* see if it is pushed or pulled somewhere else.
|
|
*/
|
|
if (p->nr_cpus_allowed != 1 &&
|
|
cpudl_find(&rq->rd->cpudl, p, NULL))
|
|
return;
|
|
|
|
resched_curr(rq);
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* Only called when both the current and waking task are -deadline
|
|
* tasks.
|
|
*/
|
|
static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
|
|
int flags)
|
|
{
|
|
if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
|
|
resched_curr(rq);
|
|
return;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* In the unlikely case current and p have the same deadline
|
|
* let us try to decide what's the best thing to do...
|
|
*/
|
|
if ((p->dl.deadline == rq->curr->dl.deadline) &&
|
|
!test_tsk_need_resched(rq->curr))
|
|
check_preempt_equal_dl(rq, p);
|
|
#endif /* CONFIG_SMP */
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
hrtick_start(rq, p->dl.runtime);
|
|
}
|
|
#else /* !CONFIG_SCHED_HRTICK */
|
|
static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
|
|
struct dl_rq *dl_rq)
|
|
{
|
|
struct rb_node *left = rb_first_cached(&dl_rq->root);
|
|
|
|
if (!left)
|
|
return NULL;
|
|
|
|
return rb_entry(left, struct sched_dl_entity, rb_node);
|
|
}
|
|
|
|
static struct task_struct *
|
|
pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
|
|
{
|
|
struct sched_dl_entity *dl_se;
|
|
struct task_struct *p;
|
|
struct dl_rq *dl_rq;
|
|
|
|
dl_rq = &rq->dl;
|
|
|
|
if (need_pull_dl_task(rq, prev)) {
|
|
/*
|
|
* This is OK, because current is on_cpu, which avoids it being
|
|
* picked for load-balance and preemption/IRQs are still
|
|
* disabled avoiding further scheduler activity on it and we're
|
|
* being very careful to re-start the picking loop.
|
|
*/
|
|
rq_unpin_lock(rq, rf);
|
|
pull_dl_task(rq);
|
|
rq_repin_lock(rq, rf);
|
|
/*
|
|
* pull_dl_task() can drop (and re-acquire) rq->lock; this
|
|
* means a stop task can slip in, in which case we need to
|
|
* re-start task selection.
|
|
*/
|
|
if (rq->stop && task_on_rq_queued(rq->stop))
|
|
return RETRY_TASK;
|
|
}
|
|
|
|
/*
|
|
* When prev is DL, we may throttle it in put_prev_task().
|
|
* So, we update time before we check for dl_nr_running.
|
|
*/
|
|
if (prev->sched_class == &dl_sched_class)
|
|
update_curr_dl(rq);
|
|
|
|
if (unlikely(!dl_rq->dl_nr_running))
|
|
return NULL;
|
|
|
|
put_prev_task(rq, prev);
|
|
|
|
dl_se = pick_next_dl_entity(rq, dl_rq);
|
|
BUG_ON(!dl_se);
|
|
|
|
p = dl_task_of(dl_se);
|
|
p->se.exec_start = rq_clock_task(rq);
|
|
|
|
/* Running task will never be pushed. */
|
|
dequeue_pushable_dl_task(rq, p);
|
|
|
|
if (hrtick_enabled(rq))
|
|
start_hrtick_dl(rq, p);
|
|
|
|
queue_push_tasks(rq);
|
|
|
|
return p;
|
|
}
|
|
|
|
static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
update_curr_dl(rq);
|
|
|
|
if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
|
|
enqueue_pushable_dl_task(rq, p);
|
|
}
|
|
|
|
static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
|
|
{
|
|
update_curr_dl(rq);
|
|
|
|
/*
|
|
* Even when we have runtime, update_curr_dl() might have resulted in us
|
|
* not being the leftmost task anymore. In that case NEED_RESCHED will
|
|
* be set and schedule() will start a new hrtick for the next task.
|
|
*/
|
|
if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
|
|
is_leftmost(p, &rq->dl))
|
|
start_hrtick_dl(rq, p);
|
|
}
|
|
|
|
static void task_fork_dl(struct task_struct *p)
|
|
{
|
|
/*
|
|
* SCHED_DEADLINE tasks cannot fork and this is achieved through
|
|
* sched_fork()
|
|
*/
|
|
}
|
|
|
|
static void set_curr_task_dl(struct rq *rq)
|
|
{
|
|
struct task_struct *p = rq->curr;
|
|
|
|
p->se.exec_start = rq_clock_task(rq);
|
|
|
|
/* You can't push away the running task */
|
|
dequeue_pushable_dl_task(rq, p);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/* Only try algorithms three times */
|
|
#define DL_MAX_TRIES 3
|
|
|
|
static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
cpumask_test_cpu(cpu, &p->cpus_allowed))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return the earliest pushable rq's task, which is suitable to be executed
|
|
* on the CPU, NULL otherwise:
|
|
*/
|
|
static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
|
|
{
|
|
struct rb_node *next_node = rq->dl.pushable_dl_tasks_root.rb_leftmost;
|
|
struct task_struct *p = NULL;
|
|
|
|
if (!has_pushable_dl_tasks(rq))
|
|
return NULL;
|
|
|
|
next_node:
|
|
if (next_node) {
|
|
p = rb_entry(next_node, struct task_struct, pushable_dl_tasks);
|
|
|
|
if (pick_dl_task(rq, p, cpu))
|
|
return p;
|
|
|
|
next_node = rb_next(next_node);
|
|
goto next_node;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
|
|
|
|
static int find_later_rq(struct task_struct *task)
|
|
{
|
|
struct sched_domain *sd;
|
|
struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
|
|
int this_cpu = smp_processor_id();
|
|
int cpu = task_cpu(task);
|
|
|
|
/* Make sure the mask is initialized first */
|
|
if (unlikely(!later_mask))
|
|
return -1;
|
|
|
|
if (task->nr_cpus_allowed == 1)
|
|
return -1;
|
|
|
|
/*
|
|
* We have to consider system topology and task affinity
|
|
* first, then we can look for a suitable cpu.
|
|
*/
|
|
if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask))
|
|
return -1;
|
|
|
|
/*
|
|
* If we are here, some targets have been found, including
|
|
* the most suitable which is, among the runqueues where the
|
|
* current tasks have later deadlines than the task's one, the
|
|
* rq with the latest possible one.
|
|
*
|
|
* Now we check how well this matches with task's
|
|
* affinity and system topology.
|
|
*
|
|
* The last cpu where the task run is our first
|
|
* guess, since it is most likely cache-hot there.
|
|
*/
|
|
if (cpumask_test_cpu(cpu, later_mask))
|
|
return cpu;
|
|
/*
|
|
* Check if this_cpu is to be skipped (i.e., it is
|
|
* not in the mask) or not.
|
|
*/
|
|
if (!cpumask_test_cpu(this_cpu, later_mask))
|
|
this_cpu = -1;
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
if (sd->flags & SD_WAKE_AFFINE) {
|
|
int best_cpu;
|
|
|
|
/*
|
|
* If possible, preempting this_cpu is
|
|
* cheaper than migrating.
|
|
*/
|
|
if (this_cpu != -1 &&
|
|
cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
|
|
rcu_read_unlock();
|
|
return this_cpu;
|
|
}
|
|
|
|
best_cpu = cpumask_first_and(later_mask,
|
|
sched_domain_span(sd));
|
|
/*
|
|
* Last chance: if a cpu being in both later_mask
|
|
* and current sd span is valid, that becomes our
|
|
* choice. Of course, the latest possible cpu is
|
|
* already under consideration through later_mask.
|
|
*/
|
|
if (best_cpu < nr_cpu_ids) {
|
|
rcu_read_unlock();
|
|
return best_cpu;
|
|
}
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* At this point, all our guesses failed, we just return
|
|
* 'something', and let the caller sort the things out.
|
|
*/
|
|
if (this_cpu != -1)
|
|
return this_cpu;
|
|
|
|
cpu = cpumask_any(later_mask);
|
|
if (cpu < nr_cpu_ids)
|
|
return cpu;
|
|
|
|
return -1;
|
|
}
|
|
|
|
/* Locks the rq it finds */
|
|
static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
|
|
{
|
|
struct rq *later_rq = NULL;
|
|
int tries;
|
|
int cpu;
|
|
|
|
for (tries = 0; tries < DL_MAX_TRIES; tries++) {
|
|
cpu = find_later_rq(task);
|
|
|
|
if ((cpu == -1) || (cpu == rq->cpu))
|
|
break;
|
|
|
|
later_rq = cpu_rq(cpu);
|
|
|
|
if (later_rq->dl.dl_nr_running &&
|
|
!dl_time_before(task->dl.deadline,
|
|
later_rq->dl.earliest_dl.curr)) {
|
|
/*
|
|
* Target rq has tasks of equal or earlier deadline,
|
|
* retrying does not release any lock and is unlikely
|
|
* to yield a different result.
|
|
*/
|
|
later_rq = NULL;
|
|
break;
|
|
}
|
|
|
|
/* Retry if something changed. */
|
|
if (double_lock_balance(rq, later_rq)) {
|
|
if (unlikely(task_rq(task) != rq ||
|
|
!cpumask_test_cpu(later_rq->cpu, &task->cpus_allowed) ||
|
|
task_running(rq, task) ||
|
|
!dl_task(task) ||
|
|
!task_on_rq_queued(task))) {
|
|
double_unlock_balance(rq, later_rq);
|
|
later_rq = NULL;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the rq we found has no -deadline task, or
|
|
* its earliest one has a later deadline than our
|
|
* task, the rq is a good one.
|
|
*/
|
|
if (!later_rq->dl.dl_nr_running ||
|
|
dl_time_before(task->dl.deadline,
|
|
later_rq->dl.earliest_dl.curr))
|
|
break;
|
|
|
|
/* Otherwise we try again. */
|
|
double_unlock_balance(rq, later_rq);
|
|
later_rq = NULL;
|
|
}
|
|
|
|
return later_rq;
|
|
}
|
|
|
|
static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
|
|
{
|
|
struct task_struct *p;
|
|
|
|
if (!has_pushable_dl_tasks(rq))
|
|
return NULL;
|
|
|
|
p = rb_entry(rq->dl.pushable_dl_tasks_root.rb_leftmost,
|
|
struct task_struct, pushable_dl_tasks);
|
|
|
|
BUG_ON(rq->cpu != task_cpu(p));
|
|
BUG_ON(task_current(rq, p));
|
|
BUG_ON(p->nr_cpus_allowed <= 1);
|
|
|
|
BUG_ON(!task_on_rq_queued(p));
|
|
BUG_ON(!dl_task(p));
|
|
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
* See if the non running -deadline tasks on this rq
|
|
* can be sent to some other CPU where they can preempt
|
|
* and start executing.
|
|
*/
|
|
static int push_dl_task(struct rq *rq)
|
|
{
|
|
struct task_struct *next_task;
|
|
struct rq *later_rq;
|
|
int ret = 0;
|
|
|
|
if (!rq->dl.overloaded)
|
|
return 0;
|
|
|
|
next_task = pick_next_pushable_dl_task(rq);
|
|
if (!next_task)
|
|
return 0;
|
|
|
|
retry:
|
|
if (unlikely(next_task == rq->curr)) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If next_task preempts rq->curr, and rq->curr
|
|
* can move away, it makes sense to just reschedule
|
|
* without going further in pushing next_task.
|
|
*/
|
|
if (dl_task(rq->curr) &&
|
|
dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
|
|
rq->curr->nr_cpus_allowed > 1) {
|
|
resched_curr(rq);
|
|
return 0;
|
|
}
|
|
|
|
/* We might release rq lock */
|
|
get_task_struct(next_task);
|
|
|
|
/* Will lock the rq it'll find */
|
|
later_rq = find_lock_later_rq(next_task, rq);
|
|
if (!later_rq) {
|
|
struct task_struct *task;
|
|
|
|
/*
|
|
* We must check all this again, since
|
|
* find_lock_later_rq releases rq->lock and it is
|
|
* then possible that next_task has migrated.
|
|
*/
|
|
task = pick_next_pushable_dl_task(rq);
|
|
if (task == next_task) {
|
|
/*
|
|
* The task is still there. We don't try
|
|
* again, some other cpu will pull it when ready.
|
|
*/
|
|
goto out;
|
|
}
|
|
|
|
if (!task)
|
|
/* No more tasks */
|
|
goto out;
|
|
|
|
put_task_struct(next_task);
|
|
next_task = task;
|
|
goto retry;
|
|
}
|
|
|
|
deactivate_task(rq, next_task, 0);
|
|
sub_running_bw(next_task->dl.dl_bw, &rq->dl);
|
|
sub_rq_bw(next_task->dl.dl_bw, &rq->dl);
|
|
set_task_cpu(next_task, later_rq->cpu);
|
|
add_rq_bw(next_task->dl.dl_bw, &later_rq->dl);
|
|
add_running_bw(next_task->dl.dl_bw, &later_rq->dl);
|
|
activate_task(later_rq, next_task, 0);
|
|
ret = 1;
|
|
|
|
resched_curr(later_rq);
|
|
|
|
double_unlock_balance(rq, later_rq);
|
|
|
|
out:
|
|
put_task_struct(next_task);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void push_dl_tasks(struct rq *rq)
|
|
{
|
|
/* push_dl_task() will return true if it moved a -deadline task */
|
|
while (push_dl_task(rq))
|
|
;
|
|
}
|
|
|
|
static void pull_dl_task(struct rq *this_rq)
|
|
{
|
|
int this_cpu = this_rq->cpu, cpu;
|
|
struct task_struct *p;
|
|
bool resched = false;
|
|
struct rq *src_rq;
|
|
u64 dmin = LONG_MAX;
|
|
|
|
if (likely(!dl_overloaded(this_rq)))
|
|
return;
|
|
|
|
/*
|
|
* Match the barrier from dl_set_overloaded; this guarantees that if we
|
|
* see overloaded we must also see the dlo_mask bit.
|
|
*/
|
|
smp_rmb();
|
|
|
|
for_each_cpu(cpu, this_rq->rd->dlo_mask) {
|
|
if (this_cpu == cpu)
|
|
continue;
|
|
|
|
src_rq = cpu_rq(cpu);
|
|
|
|
/*
|
|
* It looks racy, abd it is! However, as in sched_rt.c,
|
|
* we are fine with this.
|
|
*/
|
|
if (this_rq->dl.dl_nr_running &&
|
|
dl_time_before(this_rq->dl.earliest_dl.curr,
|
|
src_rq->dl.earliest_dl.next))
|
|
continue;
|
|
|
|
/* Might drop this_rq->lock */
|
|
double_lock_balance(this_rq, src_rq);
|
|
|
|
/*
|
|
* If there are no more pullable tasks on the
|
|
* rq, we're done with it.
|
|
*/
|
|
if (src_rq->dl.dl_nr_running <= 1)
|
|
goto skip;
|
|
|
|
p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
|
|
|
|
/*
|
|
* We found a task to be pulled if:
|
|
* - it preempts our current (if there's one),
|
|
* - it will preempt the last one we pulled (if any).
|
|
*/
|
|
if (p && dl_time_before(p->dl.deadline, dmin) &&
|
|
(!this_rq->dl.dl_nr_running ||
|
|
dl_time_before(p->dl.deadline,
|
|
this_rq->dl.earliest_dl.curr))) {
|
|
WARN_ON(p == src_rq->curr);
|
|
WARN_ON(!task_on_rq_queued(p));
|
|
|
|
/*
|
|
* Then we pull iff p has actually an earlier
|
|
* deadline than the current task of its runqueue.
|
|
*/
|
|
if (dl_time_before(p->dl.deadline,
|
|
src_rq->curr->dl.deadline))
|
|
goto skip;
|
|
|
|
resched = true;
|
|
|
|
deactivate_task(src_rq, p, 0);
|
|
sub_running_bw(p->dl.dl_bw, &src_rq->dl);
|
|
sub_rq_bw(p->dl.dl_bw, &src_rq->dl);
|
|
set_task_cpu(p, this_cpu);
|
|
add_rq_bw(p->dl.dl_bw, &this_rq->dl);
|
|
add_running_bw(p->dl.dl_bw, &this_rq->dl);
|
|
activate_task(this_rq, p, 0);
|
|
dmin = p->dl.deadline;
|
|
|
|
/* Is there any other task even earlier? */
|
|
}
|
|
skip:
|
|
double_unlock_balance(this_rq, src_rq);
|
|
}
|
|
|
|
if (resched)
|
|
resched_curr(this_rq);
|
|
}
|
|
|
|
/*
|
|
* Since the task is not running and a reschedule is not going to happen
|
|
* anytime soon on its runqueue, we try pushing it away now.
|
|
*/
|
|
static void task_woken_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
!test_tsk_need_resched(rq->curr) &&
|
|
p->nr_cpus_allowed > 1 &&
|
|
dl_task(rq->curr) &&
|
|
(rq->curr->nr_cpus_allowed < 2 ||
|
|
!dl_entity_preempt(&p->dl, &rq->curr->dl))) {
|
|
push_dl_tasks(rq);
|
|
}
|
|
}
|
|
|
|
static void set_cpus_allowed_dl(struct task_struct *p,
|
|
const struct cpumask *new_mask)
|
|
{
|
|
struct root_domain *src_rd;
|
|
struct rq *rq;
|
|
|
|
BUG_ON(!dl_task(p));
|
|
|
|
rq = task_rq(p);
|
|
src_rd = rq->rd;
|
|
/*
|
|
* Migrating a SCHED_DEADLINE task between exclusive
|
|
* cpusets (different root_domains) entails a bandwidth
|
|
* update. We already made space for us in the destination
|
|
* domain (see cpuset_can_attach()).
|
|
*/
|
|
if (!cpumask_intersects(src_rd->span, new_mask)) {
|
|
struct dl_bw *src_dl_b;
|
|
|
|
src_dl_b = dl_bw_of(cpu_of(rq));
|
|
/*
|
|
* We now free resources of the root_domain we are migrating
|
|
* off. In the worst case, sched_setattr() may temporary fail
|
|
* until we complete the update.
|
|
*/
|
|
raw_spin_lock(&src_dl_b->lock);
|
|
__dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
|
|
raw_spin_unlock(&src_dl_b->lock);
|
|
}
|
|
|
|
set_cpus_allowed_common(p, new_mask);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void rq_online_dl(struct rq *rq)
|
|
{
|
|
if (rq->dl.overloaded)
|
|
dl_set_overload(rq);
|
|
|
|
cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
|
|
if (rq->dl.dl_nr_running > 0)
|
|
cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void rq_offline_dl(struct rq *rq)
|
|
{
|
|
if (rq->dl.overloaded)
|
|
dl_clear_overload(rq);
|
|
|
|
cpudl_clear(&rq->rd->cpudl, rq->cpu);
|
|
cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
|
|
}
|
|
|
|
void __init init_sched_dl_class(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
for_each_possible_cpu(i)
|
|
zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void switched_from_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* task_non_contending() can start the "inactive timer" (if the 0-lag
|
|
* time is in the future). If the task switches back to dl before
|
|
* the "inactive timer" fires, it can continue to consume its current
|
|
* runtime using its current deadline. If it stays outside of
|
|
* SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer()
|
|
* will reset the task parameters.
|
|
*/
|
|
if (task_on_rq_queued(p) && p->dl.dl_runtime)
|
|
task_non_contending(p);
|
|
|
|
if (!task_on_rq_queued(p))
|
|
sub_rq_bw(p->dl.dl_bw, &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;
|
|
|
|
queue_pull_task(rq);
|
|
}
|
|
|
|
/*
|
|
* When switching to -deadline, we may overload the rq, then
|
|
* we try to push someone off, if possible.
|
|
*/
|
|
static void switched_to_dl(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
|
|
put_task_struct(p);
|
|
|
|
/* If p is not queued we will update its parameters at next wakeup. */
|
|
if (!task_on_rq_queued(p)) {
|
|
add_rq_bw(p->dl.dl_bw, &rq->dl);
|
|
|
|
return;
|
|
}
|
|
|
|
if (rq->curr != p) {
|
|
#ifdef CONFIG_SMP
|
|
if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
|
|
queue_push_tasks(rq);
|
|
#endif
|
|
if (dl_task(rq->curr))
|
|
check_preempt_curr_dl(rq, p, 0);
|
|
else
|
|
resched_curr(rq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the scheduling parameters of a -deadline task changed,
|
|
* a push or pull operation might be needed.
|
|
*/
|
|
static void prio_changed_dl(struct rq *rq, struct task_struct *p,
|
|
int oldprio)
|
|
{
|
|
if (task_on_rq_queued(p) || rq->curr == p) {
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* This might be too much, but unfortunately
|
|
* we don't have the old deadline value, and
|
|
* we can't argue if the task is increasing
|
|
* or lowering its prio, so...
|
|
*/
|
|
if (!rq->dl.overloaded)
|
|
queue_pull_task(rq);
|
|
|
|
/*
|
|
* If we now have a earlier deadline task than p,
|
|
* then reschedule, provided p is still on this
|
|
* runqueue.
|
|
*/
|
|
if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline))
|
|
resched_curr(rq);
|
|
#else
|
|
/*
|
|
* Again, we don't know if p has a earlier
|
|
* or later deadline, so let's blindly set a
|
|
* (maybe not needed) rescheduling point.
|
|
*/
|
|
resched_curr(rq);
|
|
#endif /* CONFIG_SMP */
|
|
}
|
|
}
|
|
|
|
const struct sched_class dl_sched_class = {
|
|
.next = &rt_sched_class,
|
|
.enqueue_task = enqueue_task_dl,
|
|
.dequeue_task = dequeue_task_dl,
|
|
.yield_task = yield_task_dl,
|
|
|
|
.check_preempt_curr = check_preempt_curr_dl,
|
|
|
|
.pick_next_task = pick_next_task_dl,
|
|
.put_prev_task = put_prev_task_dl,
|
|
|
|
#ifdef CONFIG_SMP
|
|
.select_task_rq = select_task_rq_dl,
|
|
.migrate_task_rq = migrate_task_rq_dl,
|
|
.set_cpus_allowed = set_cpus_allowed_dl,
|
|
.rq_online = rq_online_dl,
|
|
.rq_offline = rq_offline_dl,
|
|
.task_woken = task_woken_dl,
|
|
#endif
|
|
|
|
.set_curr_task = set_curr_task_dl,
|
|
.task_tick = task_tick_dl,
|
|
.task_fork = task_fork_dl,
|
|
|
|
.prio_changed = prio_changed_dl,
|
|
.switched_from = switched_from_dl,
|
|
.switched_to = switched_to_dl,
|
|
|
|
.update_curr = update_curr_dl,
|
|
};
|
|
|
|
int sched_dl_global_validate(void)
|
|
{
|
|
u64 runtime = global_rt_runtime();
|
|
u64 period = global_rt_period();
|
|
u64 new_bw = to_ratio(period, runtime);
|
|
struct dl_bw *dl_b;
|
|
int cpu, ret = 0;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* Here we want to check the bandwidth not being set to some
|
|
* value smaller than the currently allocated bandwidth in
|
|
* any of the root_domains.
|
|
*
|
|
* FIXME: Cycling on all the CPUs is overdoing, but simpler than
|
|
* cycling on root_domains... Discussion on different/better
|
|
* solutions is welcome!
|
|
*/
|
|
for_each_possible_cpu(cpu) {
|
|
rcu_read_lock_sched();
|
|
dl_b = dl_bw_of(cpu);
|
|
|
|
raw_spin_lock_irqsave(&dl_b->lock, flags);
|
|
if (new_bw < dl_b->total_bw)
|
|
ret = -EBUSY;
|
|
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
|
|
|
|
rcu_read_unlock_sched();
|
|
|
|
if (ret)
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
|
|
{
|
|
if (global_rt_runtime() == RUNTIME_INF) {
|
|
dl_rq->bw_ratio = 1 << RATIO_SHIFT;
|
|
dl_rq->extra_bw = 1 << BW_SHIFT;
|
|
} else {
|
|
dl_rq->bw_ratio = to_ratio(global_rt_runtime(),
|
|
global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT);
|
|
dl_rq->extra_bw = to_ratio(global_rt_period(),
|
|
global_rt_runtime());
|
|
}
|
|
}
|
|
|
|
void sched_dl_do_global(void)
|
|
{
|
|
u64 new_bw = -1;
|
|
struct dl_bw *dl_b;
|
|
int cpu;
|
|
unsigned long flags;
|
|
|
|
def_dl_bandwidth.dl_period = global_rt_period();
|
|
def_dl_bandwidth.dl_runtime = global_rt_runtime();
|
|
|
|
if (global_rt_runtime() != RUNTIME_INF)
|
|
new_bw = to_ratio(global_rt_period(), global_rt_runtime());
|
|
|
|
/*
|
|
* FIXME: As above...
|
|
*/
|
|
for_each_possible_cpu(cpu) {
|
|
rcu_read_lock_sched();
|
|
dl_b = dl_bw_of(cpu);
|
|
|
|
raw_spin_lock_irqsave(&dl_b->lock, flags);
|
|
dl_b->bw = new_bw;
|
|
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
|
|
|
|
rcu_read_unlock_sched();
|
|
init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must be sure that accepting a new task (or allowing changing the
|
|
* parameters of an existing one) is consistent with the bandwidth
|
|
* constraints. If yes, this function also accordingly updates the currently
|
|
* allocated bandwidth to reflect the new situation.
|
|
*
|
|
* This function is called while holding p's rq->lock.
|
|
*/
|
|
int sched_dl_overflow(struct task_struct *p, int policy,
|
|
const struct sched_attr *attr)
|
|
{
|
|
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
|
|
u64 period = attr->sched_period ?: attr->sched_deadline;
|
|
u64 runtime = attr->sched_runtime;
|
|
u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
|
|
int cpus, err = -1;
|
|
|
|
/* !deadline task may carry old deadline bandwidth */
|
|
if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
|
|
return 0;
|
|
|
|
/*
|
|
* Either if a task, enters, leave, or stays -deadline but changes
|
|
* its parameters, we may need to update accordingly the total
|
|
* allocated bandwidth of the container.
|
|
*/
|
|
raw_spin_lock(&dl_b->lock);
|
|
cpus = dl_bw_cpus(task_cpu(p));
|
|
if (dl_policy(policy) && !task_has_dl_policy(p) &&
|
|
!__dl_overflow(dl_b, cpus, 0, new_bw)) {
|
|
if (hrtimer_active(&p->dl.inactive_timer))
|
|
__dl_sub(dl_b, p->dl.dl_bw, cpus);
|
|
__dl_add(dl_b, new_bw, cpus);
|
|
err = 0;
|
|
} else if (dl_policy(policy) && task_has_dl_policy(p) &&
|
|
!__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
|
|
/*
|
|
* XXX this is slightly incorrect: when the task
|
|
* utilization decreases, we should delay the total
|
|
* utilization change until the task's 0-lag point.
|
|
* But this would require to set the task's "inactive
|
|
* timer" when the task is not inactive.
|
|
*/
|
|
__dl_sub(dl_b, p->dl.dl_bw, cpus);
|
|
__dl_add(dl_b, new_bw, cpus);
|
|
dl_change_utilization(p, new_bw);
|
|
err = 0;
|
|
} else if (!dl_policy(policy) && task_has_dl_policy(p)) {
|
|
/*
|
|
* Do not decrease the total deadline utilization here,
|
|
* switched_from_dl() will take care to do it at the correct
|
|
* (0-lag) time.
|
|
*/
|
|
err = 0;
|
|
}
|
|
raw_spin_unlock(&dl_b->lock);
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* This function initializes the sched_dl_entity of a newly becoming
|
|
* SCHED_DEADLINE task.
|
|
*
|
|
* Only the static values are considered here, the actual runtime and the
|
|
* absolute deadline will be properly calculated when the task is enqueued
|
|
* for the first time with its new policy.
|
|
*/
|
|
void __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
|
|
{
|
|
struct sched_dl_entity *dl_se = &p->dl;
|
|
|
|
dl_se->dl_runtime = attr->sched_runtime;
|
|
dl_se->dl_deadline = attr->sched_deadline;
|
|
dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
|
|
dl_se->flags = attr->sched_flags;
|
|
dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
|
|
dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime);
|
|
}
|
|
|
|
void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
|
|
{
|
|
struct sched_dl_entity *dl_se = &p->dl;
|
|
|
|
attr->sched_priority = p->rt_priority;
|
|
attr->sched_runtime = dl_se->dl_runtime;
|
|
attr->sched_deadline = dl_se->dl_deadline;
|
|
attr->sched_period = dl_se->dl_period;
|
|
attr->sched_flags = dl_se->flags;
|
|
}
|
|
|
|
/*
|
|
* This function validates the new parameters of a -deadline task.
|
|
* We ask for the deadline not being zero, and greater or equal
|
|
* than the runtime, as well as the period of being zero or
|
|
* greater than deadline. Furthermore, we have to be sure that
|
|
* user parameters are above the internal resolution of 1us (we
|
|
* check sched_runtime only since it is always the smaller one) and
|
|
* below 2^63 ns (we have to check both sched_deadline and
|
|
* sched_period, as the latter can be zero).
|
|
*/
|
|
bool __checkparam_dl(const struct sched_attr *attr)
|
|
{
|
|
/* deadline != 0 */
|
|
if (attr->sched_deadline == 0)
|
|
return false;
|
|
|
|
/*
|
|
* Since we truncate DL_SCALE bits, make sure we're at least
|
|
* that big.
|
|
*/
|
|
if (attr->sched_runtime < (1ULL << DL_SCALE))
|
|
return false;
|
|
|
|
/*
|
|
* Since we use the MSB for wrap-around and sign issues, make
|
|
* sure it's not set (mind that period can be equal to zero).
|
|
*/
|
|
if (attr->sched_deadline & (1ULL << 63) ||
|
|
attr->sched_period & (1ULL << 63))
|
|
return false;
|
|
|
|
/* runtime <= deadline <= period (if period != 0) */
|
|
if ((attr->sched_period != 0 &&
|
|
attr->sched_period < attr->sched_deadline) ||
|
|
attr->sched_deadline < attr->sched_runtime)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* This function clears the sched_dl_entity static params.
|
|
*/
|
|
void __dl_clear_params(struct task_struct *p)
|
|
{
|
|
struct sched_dl_entity *dl_se = &p->dl;
|
|
|
|
dl_se->dl_runtime = 0;
|
|
dl_se->dl_deadline = 0;
|
|
dl_se->dl_period = 0;
|
|
dl_se->flags = 0;
|
|
dl_se->dl_bw = 0;
|
|
dl_se->dl_density = 0;
|
|
|
|
dl_se->dl_throttled = 0;
|
|
dl_se->dl_yielded = 0;
|
|
dl_se->dl_non_contending = 0;
|
|
}
|
|
|
|
bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
|
|
{
|
|
struct sched_dl_entity *dl_se = &p->dl;
|
|
|
|
if (dl_se->dl_runtime != attr->sched_runtime ||
|
|
dl_se->dl_deadline != attr->sched_deadline ||
|
|
dl_se->dl_period != attr->sched_period ||
|
|
dl_se->flags != attr->sched_flags)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed)
|
|
{
|
|
unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
|
|
cs_cpus_allowed);
|
|
struct dl_bw *dl_b;
|
|
bool overflow;
|
|
int cpus, ret;
|
|
unsigned long flags;
|
|
|
|
rcu_read_lock_sched();
|
|
dl_b = dl_bw_of(dest_cpu);
|
|
raw_spin_lock_irqsave(&dl_b->lock, flags);
|
|
cpus = dl_bw_cpus(dest_cpu);
|
|
overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
|
|
if (overflow)
|
|
ret = -EBUSY;
|
|
else {
|
|
/*
|
|
* We reserve space for this task in the destination
|
|
* root_domain, as we can't fail after this point.
|
|
* We will free resources in the source root_domain
|
|
* later on (see set_cpus_allowed_dl()).
|
|
*/
|
|
__dl_add(dl_b, p->dl.dl_bw, cpus);
|
|
ret = 0;
|
|
}
|
|
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
|
|
rcu_read_unlock_sched();
|
|
return ret;
|
|
}
|
|
|
|
int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
|
|
const struct cpumask *trial)
|
|
{
|
|
int ret = 1, trial_cpus;
|
|
struct dl_bw *cur_dl_b;
|
|
unsigned long flags;
|
|
|
|
rcu_read_lock_sched();
|
|
cur_dl_b = dl_bw_of(cpumask_any(cur));
|
|
trial_cpus = cpumask_weight(trial);
|
|
|
|
raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
|
|
if (cur_dl_b->bw != -1 &&
|
|
cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
|
|
ret = 0;
|
|
raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
|
|
rcu_read_unlock_sched();
|
|
return ret;
|
|
}
|
|
|
|
bool dl_cpu_busy(unsigned int cpu)
|
|
{
|
|
unsigned long flags;
|
|
struct dl_bw *dl_b;
|
|
bool overflow;
|
|
int cpus;
|
|
|
|
rcu_read_lock_sched();
|
|
dl_b = dl_bw_of(cpu);
|
|
raw_spin_lock_irqsave(&dl_b->lock, flags);
|
|
cpus = dl_bw_cpus(cpu);
|
|
overflow = __dl_overflow(dl_b, cpus, 0, 0);
|
|
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
|
|
rcu_read_unlock_sched();
|
|
return overflow;
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq);
|
|
|
|
void print_dl_stats(struct seq_file *m, int cpu)
|
|
{
|
|
print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
|
|
}
|
|
#endif /* CONFIG_SCHED_DEBUG */
|