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git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds authoredPull workqueue updates from Tejun Heo: "Three trivial workqueue changes" * 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Fix comment for work_on_cpu() sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() workqueue: Replace usage of init_name with dev_set_name()
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds authoredPull workqueue updates from Tejun Heo: "Three trivial workqueue changes" * 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Fix comment for work_on_cpu() sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() workqueue: Replace usage of init_name with dev_set_name()
core.c 205.69 KiB
/*
* kernel/sched/core.c
*
* Kernel scheduler and related syscalls
*
* Copyright (C) 1991-2002 Linus Torvalds
*
* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
* make semaphores SMP safe
* 1998-11-19 Implemented schedule_timeout() and related stuff
* by Andrea Arcangeli
* 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
* hybrid priority-list and round-robin design with
* an array-switch method of distributing timeslices
* and per-CPU runqueues. Cleanups and useful suggestions
* by Davide Libenzi, preemptible kernel bits by Robert Love.
* 2003-09-03 Interactivity tuning by Con Kolivas.
* 2004-04-02 Scheduler domains code by Nick Piggin
* 2007-04-15 Work begun on replacing all interactivity tuning with a
* fair scheduling design by Con Kolivas.
* 2007-05-05 Load balancing (smp-nice) and other improvements
* by Peter Williams
* 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
* 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
* 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
* Thomas Gleixner, Mike Kravetz
*/
#include <linux/kasan.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/highmem.h>
#include <asm/mmu_context.h>
#include <linux/interrupt.h>
#include <linux/capability.h>
#include <linux/completion.h>
#include <linux/kernel_stat.h>
#include <linux/debug_locks.h>
#include <linux/perf_event.h>
#include <linux/security.h>
#include <linux/notifier.h>
#include <linux/profile.h>
#include <linux/freezer.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/pid_namespace.h>
#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/timer.h>
#include <linux/rcupdate.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/percpu.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include <linux/syscalls.h>
#include <linux/times.h>
#include <linux/tsacct_kern.h>
#include <linux/kprobes.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/pagemap.h>
#include <linux/hrtimer.h>
#include <linux/tick.h>
#include <linux/ctype.h>#include <linux/ftrace.h>
#include <linux/slab.h>
#include <linux/init_task.h>
#include <linux/context_tracking.h>
#include <linux/compiler.h>
#include <asm/switch_to.h>
#include <asm/tlb.h>
#include <asm/irq_regs.h>
#include <asm/mutex.h>
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#endif
#include "sched.h"
#include "../workqueue_internal.h"
#include "../smpboot.h"
#define CREATE_TRACE_POINTS
#include <trace/events/sched.h>
DEFINE_MUTEX(sched_domains_mutex);
DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
static void update_rq_clock_task(struct rq *rq, s64 delta);
void update_rq_clock(struct rq *rq)
{
s64 delta;
lockdep_assert_held(&rq->lock);
if (rq->clock_skip_update & RQCF_ACT_SKIP)
return;
delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
if (delta < 0)
return;
rq->clock += delta;
update_rq_clock_task(rq, delta);
}
/*
* Debugging: various feature bits
*/
#define SCHED_FEAT(name, enabled) \
(1UL << __SCHED_FEAT_##name) * enabled |
const_debug unsigned int sysctl_sched_features =
#include "features.h"
0;
#undef SCHED_FEAT
/*
* Number of tasks to iterate in a single balance run.
* Limited because this is done with IRQs disabled.
*/
const_debug unsigned int sysctl_sched_nr_migrate = 32;
/*
* period over which we average the RT time consumption, measured
* in ms.
*
* default: 1s
*/
const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
/* * period over which we measure -rt task cpu usage in us.
* default: 1s
*/
unsigned int sysctl_sched_rt_period = 1000000;
__read_mostly int scheduler_running;
/*
* part of the period that we allow rt tasks to run in us.
* default: 0.95s
*/
int sysctl_sched_rt_runtime = 950000;
/* cpus with isolated domains */
cpumask_var_t cpu_isolated_map;
/*
* this_rq_lock - lock this runqueue and disable interrupts.
*/
static struct rq *this_rq_lock(void)
__acquires(rq->lock)
{
struct rq *rq;
local_irq_disable();
rq = this_rq();
raw_spin_lock(&rq->lock);
return rq;
}
#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
*/
static void hrtick_clear(struct rq *rq)
{
if (hrtimer_active(&rq->hrtick_timer))
hrtimer_cancel(&rq->hrtick_timer);
}
/*
* High-resolution timer tick.
* Runs from hardirq context with interrupts disabled.
*/
static enum hrtimer_restart hrtick(struct hrtimer *timer)
{
struct rq *rq = container_of(timer, struct rq, hrtick_timer);
WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
raw_spin_lock(&rq->lock);
update_rq_clock(rq);
rq->curr->sched_class->task_tick(rq, rq->curr, 1);
raw_spin_unlock(&rq->lock);
return HRTIMER_NORESTART;
}
#ifdef CONFIG_SMP
static void __hrtick_restart(struct rq *rq)
{
struct hrtimer *timer = &rq->hrtick_timer;
hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
}
/* * called from hardirq (IPI) context
*/
static void __hrtick_start(void *arg)
{
struct rq *rq = arg;
raw_spin_lock(&rq->lock);
__hrtick_restart(rq);
rq->hrtick_csd_pending = 0;
raw_spin_unlock(&rq->lock);
}
/*
* Called to set the hrtick timer state.
*
* called with rq->lock held and irqs disabled
*/
void hrtick_start(struct rq *rq, u64 delay)
{
struct hrtimer *timer = &rq->hrtick_timer;
ktime_t time;
s64 delta;
/*
* Don't schedule slices shorter than 10000ns, that just
* doesn't make sense and can cause timer DoS.
*/
delta = max_t(s64, delay, 10000LL);
time = ktime_add_ns(timer->base->get_time(), delta);
hrtimer_set_expires(timer, time);
if (rq == this_rq()) {
__hrtick_restart(rq);
} else if (!rq->hrtick_csd_pending) {
smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
rq->hrtick_csd_pending = 1;
}
}
static int
hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int cpu = (int)(long)hcpu;
switch (action) {
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
hrtick_clear(cpu_rq(cpu));
return NOTIFY_OK;
}
return NOTIFY_DONE;
}
static __init void init_hrtick(void)
{
hotcpu_notifier(hotplug_hrtick, 0);
}
#else
/*
* Called to set the hrtick timer state.
*
* called with rq->lock held and irqs disabled
*/
void hrtick_start(struct rq *rq, u64 delay){
/*
* Don't schedule slices shorter than 10000ns, that just
* doesn't make sense. Rely on vruntime for fairness.
*/
delay = max_t(u64, delay, 10000LL);
hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
HRTIMER_MODE_REL_PINNED);
}
static inline void init_hrtick(void)
{
}
#endif /* CONFIG_SMP */
static void init_rq_hrtick(struct rq *rq)
{
#ifdef CONFIG_SMP
rq->hrtick_csd_pending = 0;
rq->hrtick_csd.flags = 0;
rq->hrtick_csd.func = __hrtick_start;
rq->hrtick_csd.info = rq;
#endif
hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
rq->hrtick_timer.function = hrtick;
}
#else /* CONFIG_SCHED_HRTICK */
static inline void hrtick_clear(struct rq *rq)
{
}
static inline void init_rq_hrtick(struct rq *rq)
{
}
static inline void init_hrtick(void)
{
}
#endif /* CONFIG_SCHED_HRTICK */
#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
/*
* Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
* this avoids any races wrt polling state changes and thereby avoids
* spurious IPIs.
*/
static bool set_nr_and_not_polling(struct task_struct *p)
{
struct thread_info *ti = task_thread_info(p);
return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
}
/*
* Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
*
* If this returns true, then the idle task promises to call
* sched_ttwu_pending() and reschedule soon.
*/
static bool set_nr_if_polling(struct task_struct *p)
{
struct thread_info *ti = task_thread_info(p);
typeof(ti->flags) old, val = READ_ONCE(ti->flags);
for (;;) {
if (!(val & _TIF_POLLING_NRFLAG))
return false;
if (val & _TIF_NEED_RESCHED)
return true; old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
if (old == val)
break;
val = old;
}
return true;
}
#else
static bool set_nr_and_not_polling(struct task_struct *p)
{
set_tsk_need_resched(p);
return true;
}
#ifdef CONFIG_SMP
static bool set_nr_if_polling(struct task_struct *p)
{
return false;
}
#endif
#endif
void wake_q_add(struct wake_q_head *head, struct task_struct *task)
{
struct wake_q_node *node = &task->wake_q;
/*
* Atomically grab the task, if ->wake_q is !nil already it means
* its already queued (either by us or someone else) and will get the
* wakeup due to that.
*
* This cmpxchg() implies a full barrier, which pairs with the write
* barrier implied by the wakeup in wake_up_list().
*/
if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
return;
get_task_struct(task);
/*
* The head is context local, there can be no concurrency.
*/
*head->lastp = node;
head->lastp = &node->next;
}
void wake_up_q(struct wake_q_head *head)
{
struct wake_q_node *node = head->first;
while (node != WAKE_Q_TAIL) {
struct task_struct *task;
task = container_of(node, struct task_struct, wake_q);
BUG_ON(!task);
/* task can safely be re-inserted now */
node = node->next;
task->wake_q.next = NULL;
/*
* wake_up_process() implies a wmb() to pair with the queueing
* in wake_q_add() so as not to miss wakeups.
*/
wake_up_process(task);
put_task_struct(task);
}
}
/* * resched_curr - mark rq's current task 'to be rescheduled now'.
*
* On UP this means the setting of the need_resched flag, on SMP it
* might also involve a cross-CPU call to trigger the scheduler on
* the target CPU.
*/
void resched_curr(struct rq *rq)
{
struct task_struct *curr = rq->curr;
int cpu;
lockdep_assert_held(&rq->lock);
if (test_tsk_need_resched(curr))
return;
cpu = cpu_of(rq);
if (cpu == smp_processor_id()) {
set_tsk_need_resched(curr);
set_preempt_need_resched();
return;
}
if (set_nr_and_not_polling(curr))
smp_send_reschedule(cpu);
else
trace_sched_wake_idle_without_ipi(cpu);
}
void resched_cpu(int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
if (!raw_spin_trylock_irqsave(&rq->lock, flags))
return;
resched_curr(rq);
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
#ifdef CONFIG_SMP
#ifdef CONFIG_NO_HZ_COMMON
/*
* In the semi idle case, use the nearest busy cpu for migrating timers
* from an idle cpu. This is good for power-savings.
*
* We don't do similar optimization for completely idle system, as
* selecting an idle cpu will add more delays to the timers than intended
* (as that cpu's timer base may not be uptodate wrt jiffies etc).
*/
int get_nohz_timer_target(void)
{
int i, cpu = smp_processor_id();
struct sched_domain *sd;
if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
return cpu;
rcu_read_lock();
for_each_domain(cpu, sd) {
for_each_cpu(i, sched_domain_span(sd)) {
if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
cpu = i;
goto unlock;
}
}
}
if (!is_housekeeping_cpu(cpu)) cpu = housekeeping_any_cpu();
unlock:
rcu_read_unlock();
return cpu;
}
/*
* When add_timer_on() enqueues a timer into the timer wheel of an
* idle CPU then this timer might expire before the next timer event
* which is scheduled to wake up that CPU. In case of a completely
* idle system the next event might even be infinite time into the
* future. wake_up_idle_cpu() ensures that the CPU is woken up and
* leaves the inner idle loop so the newly added timer is taken into
* account when the CPU goes back to idle and evaluates the timer
* wheel for the next timer event.
*/
static void wake_up_idle_cpu(int cpu)
{
struct rq *rq = cpu_rq(cpu);
if (cpu == smp_processor_id())
return;
if (set_nr_and_not_polling(rq->idle))
smp_send_reschedule(cpu);
else
trace_sched_wake_idle_without_ipi(cpu);
}
static bool wake_up_full_nohz_cpu(int cpu)
{
/*
* We just need the target to call irq_exit() and re-evaluate
* the next tick. The nohz full kick at least implies that.
* If needed we can still optimize that later with an
* empty IRQ.
*/
if (tick_nohz_full_cpu(cpu)) {
if (cpu != smp_processor_id() ||
tick_nohz_tick_stopped())
tick_nohz_full_kick_cpu(cpu);
return true;
}
return false;
}
void wake_up_nohz_cpu(int cpu)
{
if (!wake_up_full_nohz_cpu(cpu))
wake_up_idle_cpu(cpu);
}
static inline bool got_nohz_idle_kick(void)
{
int cpu = smp_processor_id();
if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
return false;
if (idle_cpu(cpu) && !need_resched())
return true;
/*
* We can't run Idle Load Balance on this CPU for this time so we
* cancel it and clear NOHZ_BALANCE_KICK
*/
clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
return false;
}
#else /* CONFIG_NO_HZ_COMMON */
static inline bool got_nohz_idle_kick(void)
{
return false;
}
#endif /* CONFIG_NO_HZ_COMMON */
#ifdef CONFIG_NO_HZ_FULL
bool sched_can_stop_tick(struct rq *rq)
{
int fifo_nr_running;
/* Deadline tasks, even if single, need the tick */
if (rq->dl.dl_nr_running)
return false;
/*
* FIFO realtime policy runs the highest priority task (after DEADLINE).
* Other runnable tasks are of a lower priority. The scheduler tick
* isn't needed.
*/
fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
if (fifo_nr_running)
return true;
/*
* Round-robin realtime tasks time slice with other tasks at the same
* realtime priority.
*/
if (rq->rt.rr_nr_running) {
if (rq->rt.rr_nr_running == 1)
return true;
else
return false;
}
/* Normal multitasking need periodic preemption checks */
if (rq->cfs.nr_running > 1)
return false;
return true;
}
#endif /* CONFIG_NO_HZ_FULL */
void sched_avg_update(struct rq *rq)
{
s64 period = sched_avg_period();
while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
/*
* Inline assembly required to prevent the compiler
* optimising this loop into a divmod call.
* See __iter_div_u64_rem() for another example of this.
*/
asm("" : "+rm" (rq->age_stamp));
rq->age_stamp += period;
rq->rt_avg /= 2;
}
}
#endif /* CONFIG_SMP */
#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
/*
* Iterate task_group tree rooted at *from, calling @down when first entering a
* node and @up when leaving it for the final time.
* * Caller must hold rcu_lock or sufficient equivalent.
*/
int walk_tg_tree_from(struct task_group *from,
tg_visitor down, tg_visitor up, void *data)
{
struct task_group *parent, *child;
int ret;
parent = from;
down:
ret = (*down)(parent, data);
if (ret)
goto out;
list_for_each_entry_rcu(child, &parent->children, siblings) {
parent = child;
goto down;
up:
continue;
}
ret = (*up)(parent, data);
if (ret || parent == from)
goto out;
child = parent;
parent = parent->parent;
if (parent)
goto up;
out:
return ret;
}
int tg_nop(struct task_group *tg, void *data)
{
return 0;
}
#endif
static void set_load_weight(struct task_struct *p)
{
int prio = p->static_prio - MAX_RT_PRIO;
struct load_weight *load = &p->se.load;
/*
* SCHED_IDLE tasks get minimal weight:
*/
if (idle_policy(p->policy)) {
load->weight = scale_load(WEIGHT_IDLEPRIO);
load->inv_weight = WMULT_IDLEPRIO;
return;
}
load->weight = scale_load(sched_prio_to_weight[prio]);
load->inv_weight = sched_prio_to_wmult[prio];
}
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
{
update_rq_clock(rq);
if (!(flags & ENQUEUE_RESTORE))
sched_info_queued(rq, p);
p->sched_class->enqueue_task(rq, p, flags);
}
static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
{
update_rq_clock(rq);
if (!(flags & DEQUEUE_SAVE))
sched_info_dequeued(rq, p); p->sched_class->dequeue_task(rq, p, flags);
}
void activate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;
enqueue_task(rq, p, flags);
}
void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible++;
dequeue_task(rq, p, flags);
}
static void update_rq_clock_task(struct rq *rq, s64 delta)
{
/*
* In theory, the compile should just see 0 here, and optimize out the call
* to sched_rt_avg_update. But I don't trust it...
*/
#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
s64 steal = 0, irq_delta = 0;
#endif
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
/*
* Since irq_time is only updated on {soft,}irq_exit, we might run into
* this case when a previous update_rq_clock() happened inside a
* {soft,}irq region.
*
* When this happens, we stop ->clock_task and only update the
* prev_irq_time stamp to account for the part that fit, so that a next
* update will consume the rest. This ensures ->clock_task is
* monotonic.
*
* It does however cause some slight miss-attribution of {soft,}irq
* time, a more accurate solution would be to update the irq_time using
* the current rq->clock timestamp, except that would require using
* atomic ops.
*/
if (irq_delta > delta)
irq_delta = delta;
rq->prev_irq_time += irq_delta;
delta -= irq_delta;
#endif
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
if (static_key_false((¶virt_steal_rq_enabled))) {
steal = paravirt_steal_clock(cpu_of(rq));
steal -= rq->prev_steal_time_rq;
if (unlikely(steal > delta))
steal = delta;
rq->prev_steal_time_rq += steal;
delta -= steal;
}
#endif
rq->clock_task += delta;
#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
sched_rt_avg_update(rq, irq_delta + steal);#endif
}
void sched_set_stop_task(int cpu, struct task_struct *stop)
{
struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
struct task_struct *old_stop = cpu_rq(cpu)->stop;
if (stop) {
/*
* Make it appear like a SCHED_FIFO task, its something
* userspace knows about and won't get confused about.
*
* Also, it will make PI more or less work without too
* much confusion -- but then, stop work should not
* rely on PI working anyway.
*/
sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
stop->sched_class = &stop_sched_class;
}
cpu_rq(cpu)->stop = stop;
if (old_stop) {
/*
* Reset it back to a normal scheduling class so that
* it can die in pieces.
*/
old_stop->sched_class = &rt_sched_class;
}
}
/*
* __normal_prio - return the priority that is based on the static prio
*/
static inline int __normal_prio(struct task_struct *p)
{
return p->static_prio;
}
/*
* Calculate the expected normal priority: i.e. priority
* without taking RT-inheritance into account. Might be
* boosted by interactivity modifiers. Changes upon fork,
* setprio syscalls, and whenever the interactivity
* estimator recalculates.
*/
static inline int normal_prio(struct task_struct *p)
{
int prio;
if (task_has_dl_policy(p))
prio = MAX_DL_PRIO-1;
else if (task_has_rt_policy(p))
prio = MAX_RT_PRIO-1 - p->rt_priority;
else
prio = __normal_prio(p);
return prio;
}
/*
* Calculate the current priority, i.e. the priority
* taken into account by the scheduler. This value might
* be boosted by RT tasks, or might be boosted by
* interactivity modifiers. Will be RT if the task got
* RT-boosted. If not then it returns p->normal_prio.
*/
static int effective_prio(struct task_struct *p)
{ p->normal_prio = normal_prio(p);
/*
* If we are RT tasks or we were boosted to RT priority,
* keep the priority unchanged. Otherwise, update priority
* to the normal priority:
*/
if (!rt_prio(p->prio))
return p->normal_prio;
return p->prio;
}
/**
* task_curr - is this task currently executing on a CPU?
* @p: the task in question.
*
* Return: 1 if the task is currently executing. 0 otherwise.
*/
inline int task_curr(const struct task_struct *p)
{
return cpu_curr(task_cpu(p)) == p;
}
/*
* switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
* use the balance_callback list if you want balancing.
*
* this means any call to check_class_changed() must be followed by a call to
* balance_callback().
*/
static inline void check_class_changed(struct rq *rq, struct task_struct *p,
const struct sched_class *prev_class,
int oldprio)
{
if (prev_class != p->sched_class) {
if (prev_class->switched_from)
prev_class->switched_from(rq, p);
p->sched_class->switched_to(rq, p);
} else if (oldprio != p->prio || dl_task(p))
p->sched_class->prio_changed(rq, p, oldprio);
}
void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
{
const struct sched_class *class;
if (p->sched_class == rq->curr->sched_class) {
rq->curr->sched_class->check_preempt_curr(rq, p, flags);
} else {
for_each_class(class) {
if (class == rq->curr->sched_class)
break;
if (class == p->sched_class) {
resched_curr(rq);
break;
}
}
}
/*
* A queue event has occurred, and we're going to schedule. In
* this case, we can save a useless back to back clock update.
*/
if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
rq_clock_skip_update(rq, true);
}
#ifdef CONFIG_SMP
/*
* This is how migration works: *
* 1) we invoke migration_cpu_stop() on the target CPU using
* stop_one_cpu().
* 2) stopper starts to run (implicitly forcing the migrated thread
* off the CPU)
* 3) it checks whether the migrated task is still in the wrong runqueue.
* 4) if it's in the wrong runqueue then the migration thread removes
* it and puts it into the right queue.
* 5) stopper completes and stop_one_cpu() returns and the migration
* is done.
*/
/*
* move_queued_task - move a queued task to new rq.
*
* Returns (locked) new rq. Old rq's lock is released.
*/
static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
{
lockdep_assert_held(&rq->lock);
p->on_rq = TASK_ON_RQ_MIGRATING;
dequeue_task(rq, p, 0);
set_task_cpu(p, new_cpu);
raw_spin_unlock(&rq->lock);
rq = cpu_rq(new_cpu);
raw_spin_lock(&rq->lock);
BUG_ON(task_cpu(p) != new_cpu);
enqueue_task(rq, p, 0);
p->on_rq = TASK_ON_RQ_QUEUED;
check_preempt_curr(rq, p, 0);
return rq;
}
struct migration_arg {
struct task_struct *task;
int dest_cpu;
};
/*
* Move (not current) task off this cpu, onto dest cpu. We're doing
* this because either it can't run here any more (set_cpus_allowed()
* away from this CPU, or CPU going down), or because we're
* attempting to rebalance this task on exec (sched_exec).
*
* So we race with normal scheduler movements, but that's OK, as long
* as the task is no longer on this CPU.
*/
static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
{
if (unlikely(!cpu_active(dest_cpu)))
return rq;
/* Affinity changed (again). */
if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
return rq;
rq = move_queued_task(rq, p, dest_cpu);
return rq;
}
/*
* migration_cpu_stop - this will be executed by a highprio stopper thread
* and performs thread migration by bumping thread off CPU then
* 'pushing' onto another runqueue.
*/static int migration_cpu_stop(void *data)
{
struct migration_arg *arg = data;
struct task_struct *p = arg->task;
struct rq *rq = this_rq();
/*
* The original target cpu might have gone down and we might
* be on another cpu but it doesn't matter.
*/
local_irq_disable();
/*
* We need to explicitly wake pending tasks before running
* __migrate_task() such that we will not miss enforcing cpus_allowed
* during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
*/
sched_ttwu_pending();
raw_spin_lock(&p->pi_lock);
raw_spin_lock(&rq->lock);
/*
* If task_rq(p) != rq, it cannot be migrated here, because we're
* holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
* we're holding p->pi_lock.
*/
if (task_rq(p) == rq && task_on_rq_queued(p))
rq = __migrate_task(rq, p, arg->dest_cpu);
raw_spin_unlock(&rq->lock);
raw_spin_unlock(&p->pi_lock);
local_irq_enable();
return 0;
}
/*
* sched_class::set_cpus_allowed must do the below, but is not required to
* actually call this function.
*/
void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
{
cpumask_copy(&p->cpus_allowed, new_mask);
p->nr_cpus_allowed = cpumask_weight(new_mask);
}
void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
{
struct rq *rq = task_rq(p);
bool queued, running;
lockdep_assert_held(&p->pi_lock);
queued = task_on_rq_queued(p);
running = task_current(rq, p);
if (queued) {
/*
* Because __kthread_bind() calls this on blocked tasks without
* holding rq->lock.
*/
lockdep_assert_held(&rq->lock);
dequeue_task(rq, p, DEQUEUE_SAVE);
}
if (running)
put_prev_task(rq, p);
p->sched_class->set_cpus_allowed(p, new_mask);
if (running)
p->sched_class->set_curr_task(rq);
if (queued) enqueue_task(rq, p, ENQUEUE_RESTORE);
}
/*
* Change a given task's CPU affinity. Migrate the thread to a
* proper CPU and schedule it away if the CPU it's executing on
* is removed from the allowed bitmask.
*
* NOTE: the caller must have a valid reference to the task, the
* task must not exit() & deallocate itself prematurely. The
* call is not atomic; no spinlocks may be held.
*/
static int __set_cpus_allowed_ptr(struct task_struct *p,
const struct cpumask *new_mask, bool check)
{
unsigned long flags;
struct rq *rq;
unsigned int dest_cpu;
int ret = 0;
rq = task_rq_lock(p, &flags);
/*
* Must re-check here, to close a race against __kthread_bind(),
* sched_setaffinity() is not guaranteed to observe the flag.
*/
if (check && (p->flags & PF_NO_SETAFFINITY)) {
ret = -EINVAL;
goto out;
}
if (cpumask_equal(&p->cpus_allowed, new_mask))
goto out;
if (!cpumask_intersects(new_mask, cpu_active_mask)) {
ret = -EINVAL;
goto out;
}
do_set_cpus_allowed(p, new_mask);
/* Can the task run on the task's current CPU? If so, we're done */
if (cpumask_test_cpu(task_cpu(p), new_mask))
goto out;
dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
if (task_running(rq, p) || p->state == TASK_WAKING) {
struct migration_arg arg = { p, dest_cpu };
/* Need help from migration thread: drop lock and wait. */
task_rq_unlock(rq, p, &flags);
stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
tlb_migrate_finish(p->mm);
return 0;
} else if (task_on_rq_queued(p)) {
/*
* OK, since we're going to drop the lock immediately
* afterwards anyway.
*/
lockdep_unpin_lock(&rq->lock);
rq = move_queued_task(rq, p, dest_cpu);
lockdep_pin_lock(&rq->lock);
}
out:
task_rq_unlock(rq, p, &flags);
return ret;
}
int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
{ return __set_cpus_allowed_ptr(p, new_mask, false);
}
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
#ifdef CONFIG_SCHED_DEBUG
/*
* We should never call set_task_cpu() on a blocked task,
* ttwu() will sort out the placement.
*/
WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
!p->on_rq);
/*
* Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
* because schedstat_wait_{start,end} rebase migrating task's wait_start
* time relying on p->on_rq.
*/
WARN_ON_ONCE(p->state == TASK_RUNNING &&
p->sched_class == &fair_sched_class &&
(p->on_rq && !task_on_rq_migrating(p)));
#ifdef CONFIG_LOCKDEP
/*
* The caller should hold either p->pi_lock or rq->lock, when changing
* a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
*
* sched_move_task() holds both and thus holding either pins the cgroup,
* see task_group().
*
* Furthermore, all task_rq users should acquire both locks, see
* task_rq_lock().
*/
WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
lockdep_is_held(&task_rq(p)->lock)));
#endif
#endif
trace_sched_migrate_task(p, new_cpu);
if (task_cpu(p) != new_cpu) {
if (p->sched_class->migrate_task_rq)
p->sched_class->migrate_task_rq(p);
p->se.nr_migrations++;
perf_event_task_migrate(p);
}
__set_task_cpu(p, new_cpu);
}
static void __migrate_swap_task(struct task_struct *p, int cpu)
{
if (task_on_rq_queued(p)) {
struct rq *src_rq, *dst_rq;
src_rq = task_rq(p);
dst_rq = cpu_rq(cpu);
p->on_rq = TASK_ON_RQ_MIGRATING;
deactivate_task(src_rq, p, 0);
set_task_cpu(p, cpu);
activate_task(dst_rq, p, 0);
p->on_rq = TASK_ON_RQ_QUEUED;
check_preempt_curr(dst_rq, p, 0);
} else {
/*
* Task isn't running anymore; make it appear like we migrated
* it before it went to sleep. This means on wakeup we make the
* previous cpu our targer instead of where it really is. */
p->wake_cpu = cpu;
}
}
struct migration_swap_arg {
struct task_struct *src_task, *dst_task;
int src_cpu, dst_cpu;
};
static int migrate_swap_stop(void *data)
{
struct migration_swap_arg *arg = data;
struct rq *src_rq, *dst_rq;
int ret = -EAGAIN;
if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
return -EAGAIN;
src_rq = cpu_rq(arg->src_cpu);
dst_rq = cpu_rq(arg->dst_cpu);
double_raw_lock(&arg->src_task->pi_lock,
&arg->dst_task->pi_lock);
double_rq_lock(src_rq, dst_rq);
if (task_cpu(arg->dst_task) != arg->dst_cpu)
goto unlock;
if (task_cpu(arg->src_task) != arg->src_cpu)
goto unlock;
if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
goto unlock;
if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
goto unlock;
__migrate_swap_task(arg->src_task, arg->dst_cpu);
__migrate_swap_task(arg->dst_task, arg->src_cpu);
ret = 0;
unlock:
double_rq_unlock(src_rq, dst_rq);
raw_spin_unlock(&arg->dst_task->pi_lock);
raw_spin_unlock(&arg->src_task->pi_lock);
return ret;
}
/*
* Cross migrate two tasks
*/
int migrate_swap(struct task_struct *cur, struct task_struct *p)
{
struct migration_swap_arg arg;
int ret = -EINVAL;
arg = (struct migration_swap_arg){
.src_task = cur,
.src_cpu = task_cpu(cur),
.dst_task = p,
.dst_cpu = task_cpu(p),
};
if (arg.src_cpu == arg.dst_cpu)
goto out;
/* * These three tests are all lockless; this is OK since all of them
* will be re-checked with proper locks held further down the line.
*/
if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
goto out;
if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
goto out;
if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
goto out;
trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
out:
return ret;
}
/*
* wait_task_inactive - wait for a thread to unschedule.
*
* If @match_state is nonzero, it's the @p->state value just checked and
* not expected to change. If it changes, i.e. @p might have woken up,
* then return zero. When we succeed in waiting for @p to be off its CPU,
* we return a positive number (its total switch count). If a second call
* a short while later returns the same number, the caller can be sure that
* @p has remained unscheduled the whole time.
*
* The caller must ensure that the task *will* unschedule sometime soon,
* else this function might spin for a *long* time. This function can't
* be called with interrupts off, or it may introduce deadlock with
* smp_call_function() if an IPI is sent by the same process we are
* waiting to become inactive.
*/
unsigned long wait_task_inactive(struct task_struct *p, long match_state)
{
unsigned long flags;
int running, queued;
unsigned long ncsw;
struct rq *rq;
for (;;) {
/*
* We do the initial early heuristics without holding
* any task-queue locks at all. We'll only try to get
* the runqueue lock when things look like they will
* work out!
*/
rq = task_rq(p);
/*
* If the task is actively running on another CPU
* still, just relax and busy-wait without holding
* any locks.
*
* NOTE! Since we don't hold any locks, it's not
* even sure that "rq" stays as the right runqueue!
* But we don't care, since "task_running()" will
* return false if the runqueue has changed and p
* is actually now running somewhere else!
*/
while (task_running(rq, p)) {
if (match_state && unlikely(p->state != match_state))
return 0;
cpu_relax();
}
/*
* Ok, time to look more closely! We need the rq * lock now, to be *sure*. If we're wrong, we'll
* just go back and repeat.
*/
rq = task_rq_lock(p, &flags);
trace_sched_wait_task(p);
running = task_running(rq, p);
queued = task_on_rq_queued(p);
ncsw = 0;
if (!match_state || p->state == match_state)
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
task_rq_unlock(rq, p, &flags);
/*
* If it changed from the expected state, bail out now.
*/
if (unlikely(!ncsw))
break;
/*
* Was it really running after all now that we
* checked with the proper locks actually held?
*
* Oops. Go back and try again..
*/
if (unlikely(running)) {
cpu_relax();
continue;
}
/*
* It's not enough that it's not actively running,
* it must be off the runqueue _entirely_, and not
* preempted!
*
* So if it was still runnable (but just not actively
* running right now), it's preempted, and we should
* yield - it could be a while.
*/
if (unlikely(queued)) {
ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_hrtimeout(&to, HRTIMER_MODE_REL);
continue;
}
/*
* Ahh, all good. It wasn't running, and it wasn't
* runnable, which means that it will never become
* running in the future either. We're all done!
*/
break;
}
return ncsw;
}
/***
* kick_process - kick a running thread to enter/exit the kernel
* @p: the to-be-kicked thread
*
* Cause a process which is running on another CPU to enter
* kernel-mode, without any delay. (to get signals handled.)
*
* NOTE: this function doesn't have to take the runqueue lock,
* because all it wants to ensure is that the remote task enters
* the kernel. If the IPI races and the task has been migrated
* to another CPU then no harm is done and the purpose has been
* achieved as well.
*/void kick_process(struct task_struct *p)
{
int cpu;
preempt_disable();
cpu = task_cpu(p);
if ((cpu != smp_processor_id()) && task_curr(p))
smp_send_reschedule(cpu);
preempt_enable();
}
EXPORT_SYMBOL_GPL(kick_process);
/*
* ->cpus_allowed is protected by both rq->lock and p->pi_lock
*/
static int select_fallback_rq(int cpu, struct task_struct *p)
{
int nid = cpu_to_node(cpu);
const struct cpumask *nodemask = NULL;
enum { cpuset, possible, fail } state = cpuset;
int dest_cpu;
/*
* If the node that the cpu is on has been offlined, cpu_to_node()
* will return -1. There is no cpu on the node, and we should
* select the cpu on the other node.
*/
if (nid != -1) {
nodemask = cpumask_of_node(nid);
/* Look for allowed, online CPU in same node. */
for_each_cpu(dest_cpu, nodemask) {
if (!cpu_online(dest_cpu))
continue;
if (!cpu_active(dest_cpu))
continue;
if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
return dest_cpu;
}
}
for (;;) {
/* Any allowed, online CPU? */
for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
if (!cpu_online(dest_cpu))
continue;
if (!cpu_active(dest_cpu))
continue;
goto out;
}
/* No more Mr. Nice Guy. */
switch (state) {
case cpuset:
if (IS_ENABLED(CONFIG_CPUSETS)) {
cpuset_cpus_allowed_fallback(p);
state = possible;
break;
}
/* fall-through */
case possible:
do_set_cpus_allowed(p, cpu_possible_mask);
state = fail;
break;
case fail:
BUG();
break;
}
}
out:
if (state != cpuset) {
/*
* Don't tell them about moving exiting tasks or
* kernel threads (both mm NULL), since they never
* leave kernel.
*/
if (p->mm && printk_ratelimit()) {
printk_deferred("process %d (%s) no longer affine to cpu%d\n",
task_pid_nr(p), p->comm, cpu);
}
}
return dest_cpu;
}
/*
* The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
*/
static inline
int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
{
lockdep_assert_held(&p->pi_lock);
if (p->nr_cpus_allowed > 1)
cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
/*
* In order not to call set_task_cpu() on a blocking task we need
* to rely on ttwu() to place the task on a valid ->cpus_allowed
* cpu.
*
* Since this is common to all placement strategies, this lives here.
*
* [ this allows ->select_task() to simply return task_cpu(p) and
* not worry about this generic constraint ]
*/
if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
!cpu_online(cpu)))
cpu = select_fallback_rq(task_cpu(p), p);
return cpu;
}
static void update_avg(u64 *avg, u64 sample)
{
s64 diff = sample - *avg;
*avg += diff >> 3;
}
#else
static inline int __set_cpus_allowed_ptr(struct task_struct *p,
const struct cpumask *new_mask, bool check)
{
return set_cpus_allowed_ptr(p, new_mask);
}
#endif /* CONFIG_SMP */
static void
ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
{
#ifdef CONFIG_SCHEDSTATS
struct rq *rq = this_rq();
#ifdef CONFIG_SMP
int this_cpu = smp_processor_id();
if (cpu == this_cpu) {
schedstat_inc(rq, ttwu_local);
schedstat_inc(p, se.statistics.nr_wakeups_local);
} else {
struct sched_domain *sd;
schedstat_inc(p, se.statistics.nr_wakeups_remote);
rcu_read_lock();
for_each_domain(this_cpu, sd) {
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
schedstat_inc(sd, ttwu_wake_remote);
break;
}
}
rcu_read_unlock();
}
if (wake_flags & WF_MIGRATED)
schedstat_inc(p, se.statistics.nr_wakeups_migrate);
#endif /* CONFIG_SMP */
schedstat_inc(rq, ttwu_count);
schedstat_inc(p, se.statistics.nr_wakeups);
if (wake_flags & WF_SYNC)
schedstat_inc(p, se.statistics.nr_wakeups_sync);
#endif /* CONFIG_SCHEDSTATS */
}
static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
{
activate_task(rq, p, en_flags);
p->on_rq = TASK_ON_RQ_QUEUED;
/* if a worker is waking up, notify workqueue */
if (p->flags & PF_WQ_WORKER)
wq_worker_waking_up(p, cpu_of(rq));
}
/*
* Mark the task runnable and perform wakeup-preemption.
*/
static void
ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
{
check_preempt_curr(rq, p, wake_flags);
p->state = TASK_RUNNING;
trace_sched_wakeup(p);
#ifdef CONFIG_SMP
if (p->sched_class->task_woken) {
/*
* Our task @p is fully woken up and running; so its safe to
* drop the rq->lock, hereafter rq is only used for statistics.
*/
lockdep_unpin_lock(&rq->lock);
p->sched_class->task_woken(rq, p);
lockdep_pin_lock(&rq->lock);
}
if (rq->idle_stamp) {
u64 delta = rq_clock(rq) - rq->idle_stamp;
u64 max = 2*rq->max_idle_balance_cost;
update_avg(&rq->avg_idle, delta);
if (rq->avg_idle > max)
rq->avg_idle = max;
rq->idle_stamp = 0;
}
#endif
}
static void
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
{
lockdep_assert_held(&rq->lock);
#ifdef CONFIG_SMP
if (p->sched_contributes_to_load)
rq->nr_uninterruptible--;
#endif
ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
ttwu_do_wakeup(rq, p, wake_flags);
}
/*
* Called in case the task @p isn't fully descheduled from its runqueue,
* in this case we must do a remote wakeup. Its a 'light' wakeup though,
* since all we need to do is flip p->state to TASK_RUNNING, since
* the task is still ->on_rq.
*/
static int ttwu_remote(struct task_struct *p, int wake_flags)
{
struct rq *rq;
int ret = 0;
rq = __task_rq_lock(p);
if (task_on_rq_queued(p)) {
/* check_preempt_curr() may use rq clock */
update_rq_clock(rq);
ttwu_do_wakeup(rq, p, wake_flags);
ret = 1;
}
__task_rq_unlock(rq);
return ret;
}
#ifdef CONFIG_SMP
void sched_ttwu_pending(void)
{
struct rq *rq = this_rq();
struct llist_node *llist = llist_del_all(&rq->wake_list);
struct task_struct *p;
unsigned long flags;
if (!llist)
return;
raw_spin_lock_irqsave(&rq->lock, flags);
lockdep_pin_lock(&rq->lock);
while (llist) {
p = llist_entry(llist, struct task_struct, wake_entry);
llist = llist_next(llist);
ttwu_do_activate(rq, p, 0);
}
lockdep_unpin_lock(&rq->lock);
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
void scheduler_ipi(void)
{
/* * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
* TIF_NEED_RESCHED remotely (for the first time) will also send
* this IPI.
*/
preempt_fold_need_resched();
if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
return;
/*
* Not all reschedule IPI handlers call irq_enter/irq_exit, since
* traditionally all their work was done from the interrupt return
* path. Now that we actually do some work, we need to make sure
* we do call them.
*
* Some archs already do call them, luckily irq_enter/exit nest
* properly.
*
* Arguably we should visit all archs and update all handlers,
* however a fair share of IPIs are still resched only so this would
* somewhat pessimize the simple resched case.
*/
irq_enter();
sched_ttwu_pending();
/*
* Check if someone kicked us for doing the nohz idle load balance.
*/
if (unlikely(got_nohz_idle_kick())) {
this_rq()->idle_balance = 1;
raise_softirq_irqoff(SCHED_SOFTIRQ);
}
irq_exit();
}
static void ttwu_queue_remote(struct task_struct *p, int cpu)
{
struct rq *rq = cpu_rq(cpu);
if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
if (!set_nr_if_polling(rq->idle))
smp_send_reschedule(cpu);
else
trace_sched_wake_idle_without_ipi(cpu);
}
}
void wake_up_if_idle(int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
rcu_read_lock();
if (!is_idle_task(rcu_dereference(rq->curr)))
goto out;
if (set_nr_if_polling(rq->idle)) {
trace_sched_wake_idle_without_ipi(cpu);
} else {
raw_spin_lock_irqsave(&rq->lock, flags);
if (is_idle_task(rq->curr))
smp_send_reschedule(cpu);
/* Else cpu is not in idle, do nothing here */
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
out:
rcu_read_unlock();
}
bool cpus_share_cache(int this_cpu, int that_cpu)
{
return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
}
#endif /* CONFIG_SMP */
static void ttwu_queue(struct task_struct *p, int cpu)
{
struct rq *rq = cpu_rq(cpu);
#if defined(CONFIG_SMP)
if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
sched_clock_cpu(cpu); /* sync clocks x-cpu */
ttwu_queue_remote(p, cpu);
return;
}
#endif
raw_spin_lock(&rq->lock);
lockdep_pin_lock(&rq->lock);
ttwu_do_activate(rq, p, 0);
lockdep_unpin_lock(&rq->lock);
raw_spin_unlock(&rq->lock);
}
/*
* Notes on Program-Order guarantees on SMP systems.
*
* MIGRATION
*
* The basic program-order guarantee on SMP systems is that when a task [t]
* migrates, all its activity on its old cpu [c0] happens-before any subsequent
* execution on its new cpu [c1].
*
* For migration (of runnable tasks) this is provided by the following means:
*
* A) UNLOCK of the rq(c0)->lock scheduling out task t
* B) migration for t is required to synchronize *both* rq(c0)->lock and
* rq(c1)->lock (if not at the same time, then in that order).
* C) LOCK of the rq(c1)->lock scheduling in task
*
* Transitivity guarantees that B happens after A and C after B.
* Note: we only require RCpc transitivity.
* Note: the cpu doing B need not be c0 or c1
*
* Example:
*
* CPU0 CPU1 CPU2
*
* LOCK rq(0)->lock
* sched-out X
* sched-in Y
* UNLOCK rq(0)->lock
*
* LOCK rq(0)->lock // orders against CPU0
* dequeue X
* UNLOCK rq(0)->lock
*
* LOCK rq(1)->lock
* enqueue X
* UNLOCK rq(1)->lock
*
* LOCK rq(1)->lock // orders against CPU2
* sched-out Z
* sched-in X
* UNLOCK rq(1)->lock
*
*
* BLOCKING -- aka. SLEEP + WAKEUP *
* For blocking we (obviously) need to provide the same guarantee as for
* migration. However the means are completely different as there is no lock
* chain to provide order. Instead we do:
*
* 1) smp_store_release(X->on_cpu, 0)
* 2) smp_cond_acquire(!X->on_cpu)
*
* Example:
*
* CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
*
* LOCK rq(0)->lock LOCK X->pi_lock
* dequeue X
* sched-out X
* smp_store_release(X->on_cpu, 0);
*
* smp_cond_acquire(!X->on_cpu);
* X->state = WAKING
* set_task_cpu(X,2)
*
* LOCK rq(2)->lock
* enqueue X
* X->state = RUNNING
* UNLOCK rq(2)->lock
*
* LOCK rq(2)->lock // orders against CPU1
* sched-out Z
* sched-in X
* UNLOCK rq(2)->lock
*
* UNLOCK X->pi_lock
* UNLOCK rq(0)->lock
*
*
* However; for wakeups there is a second guarantee we must provide, namely we
* must observe the state that lead to our wakeup. That is, not only must our
* task observe its own prior state, it must also observe the stores prior to
* its wakeup.
*
* This means that any means of doing remote wakeups must order the CPU doing
* the wakeup against the CPU the task is going to end up running on. This,
* however, is already required for the regular Program-Order guarantee above,
* since the waking CPU is the one issueing the ACQUIRE (smp_cond_acquire).
*
*/
/**
* try_to_wake_up - wake up a thread
* @p: the thread to be awakened
* @state: the mask of task states that can be woken
* @wake_flags: wake modifier flags (WF_*)
*
* Put it on the run-queue if it's not already there. The "current"
* thread is always on the run-queue (except when the actual
* re-schedule is in progress), and as such you're allowed to do
* the simpler "current->state = TASK_RUNNING" to mark yourself
* runnable without the overhead of this.
*
* Return: %true if @p was woken up, %false if it was already running.
* or @state didn't match @p's state.
*/
static int
try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
{
unsigned long flags;
int cpu, success = 0;
/*
* If we are going to wake up a thread waiting for CONDITION we * need to ensure that CONDITION=1 done by the caller can not be
* reordered with p->state check below. This pairs with mb() in
* set_current_state() the waiting thread does.
*/
smp_mb__before_spinlock();
raw_spin_lock_irqsave(&p->pi_lock, flags);
if (!(p->state & state))
goto out;
trace_sched_waking(p);
success = 1; /* we're going to change ->state */
cpu = task_cpu(p);
if (p->on_rq && ttwu_remote(p, wake_flags))
goto stat;
#ifdef CONFIG_SMP
/*
* Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
* possible to, falsely, observe p->on_cpu == 0.
*
* One must be running (->on_cpu == 1) in order to remove oneself
* from the runqueue.
*
* [S] ->on_cpu = 1; [L] ->on_rq
* UNLOCK rq->lock
* RMB
* LOCK rq->lock
* [S] ->on_rq = 0; [L] ->on_cpu
*
* Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
* from the consecutive calls to schedule(); the first switching to our
* task, the second putting it to sleep.
*/
smp_rmb();
/*
* If the owning (remote) cpu is still in the middle of schedule() with
* this task as prev, wait until its done referencing the task.
*
* Pairs with the smp_store_release() in finish_lock_switch().
*
* This ensures that tasks getting woken will be fully ordered against
* their previous state and preserve Program Order.
*/
smp_cond_acquire(!p->on_cpu);
p->sched_contributes_to_load = !!task_contributes_to_load(p);
p->state = TASK_WAKING;
if (p->sched_class->task_waking)
p->sched_class->task_waking(p);
cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
if (task_cpu(p) != cpu) {
wake_flags |= WF_MIGRATED;
set_task_cpu(p, cpu);
}
#endif /* CONFIG_SMP */
ttwu_queue(p, cpu);
stat:
if (schedstat_enabled())
ttwu_stat(p, cpu, wake_flags);
out:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return success;
}
/**
* try_to_wake_up_local - try to wake up a local task with rq lock held
* @p: the thread to be awakened
*
* Put @p on the run-queue if it's not already there. The caller must
* ensure that this_rq() is locked, @p is bound to this_rq() and not
* the current task.
*/
static void try_to_wake_up_local(struct task_struct *p)
{
struct rq *rq = task_rq(p);
if (WARN_ON_ONCE(rq != this_rq()) ||
WARN_ON_ONCE(p == current))
return;
lockdep_assert_held(&rq->lock);
if (!raw_spin_trylock(&p->pi_lock)) {
/*
* This is OK, because current is on_cpu, which avoids it being
* picked for load-balance and preemption/IRQs are still
* disabled avoiding further scheduler activity on it and we've
* not yet picked a replacement task.
*/
lockdep_unpin_lock(&rq->lock);
raw_spin_unlock(&rq->lock);
raw_spin_lock(&p->pi_lock);
raw_spin_lock(&rq->lock);
lockdep_pin_lock(&rq->lock);
}
if (!(p->state & TASK_NORMAL))
goto out;
trace_sched_waking(p);
if (!task_on_rq_queued(p))
ttwu_activate(rq, p, ENQUEUE_WAKEUP);
ttwu_do_wakeup(rq, p, 0);
if (schedstat_enabled())
ttwu_stat(p, smp_processor_id(), 0);
out:
raw_spin_unlock(&p->pi_lock);
}
/**
* wake_up_process - Wake up a specific process
* @p: The process to be woken up.
*
* Attempt to wake up the nominated process and move it to the set of runnable
* processes.
*
* Return: 1 if the process was woken up, 0 if it was already running.
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
*/
int wake_up_process(struct task_struct *p)
{
return try_to_wake_up(p, TASK_NORMAL, 0);
}
EXPORT_SYMBOL(wake_up_process);
int wake_up_state(struct task_struct *p, unsigned int state)
{
return try_to_wake_up(p, state, 0);
}
/*
* 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_throttled = 0;
dl_se->dl_yielded = 0;
}
/*
* Perform scheduler related setup for a newly forked process p.
* p is forked by current.
*
* __sched_fork() is basic setup used by init_idle() too:
*/
static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
{
p->on_rq = 0;
p->se.on_rq = 0;
p->se.exec_start = 0;
p->se.sum_exec_runtime = 0;
p->se.prev_sum_exec_runtime = 0;
p->se.nr_migrations = 0;
p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_FAIR_GROUP_SCHED
p->se.cfs_rq = NULL;
#endif
#ifdef CONFIG_SCHEDSTATS
/* Even if schedstat is disabled, there should not be garbage */
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif
RB_CLEAR_NODE(&p->dl.rb_node);
init_dl_task_timer(&p->dl);
__dl_clear_params(p);
INIT_LIST_HEAD(&p->rt.run_list);
p->rt.timeout = 0;
p->rt.time_slice = sched_rr_timeslice;
p->rt.on_rq = 0;
p->rt.on_list = 0;
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&p->preempt_notifiers);
#endif
#ifdef CONFIG_NUMA_BALANCING
if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
p->mm->numa_scan_seq = 0;
}
if (clone_flags & CLONE_VM)
p->numa_preferred_nid = current->numa_preferred_nid;
else
p->numa_preferred_nid = -1;
p->node_stamp = 0ULL;
p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
p->numa_scan_period = sysctl_numa_balancing_scan_delay;
p->numa_work.next = &p->numa_work;
p->numa_faults = NULL;
p->last_task_numa_placement = 0;
p->last_sum_exec_runtime = 0;
p->numa_group = NULL;
#endif /* CONFIG_NUMA_BALANCING */
}
DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
#ifdef CONFIG_NUMA_BALANCING
void set_numabalancing_state(bool enabled)
{
if (enabled)
static_branch_enable(&sched_numa_balancing);
else
static_branch_disable(&sched_numa_balancing);
}
#ifdef CONFIG_PROC_SYSCTL
int sysctl_numa_balancing(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
struct ctl_table t;
int err;
int state = static_branch_likely(&sched_numa_balancing);
if (write && !capable(CAP_SYS_ADMIN))
return -EPERM;
t = *table;
t.data = &state;
err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
if (err < 0)
return err;
if (write)
set_numabalancing_state(state);
return err;
}
#endif
#endif
DEFINE_STATIC_KEY_FALSE(sched_schedstats);
#ifdef CONFIG_SCHEDSTATS
static void set_schedstats(bool enabled)
{
if (enabled)
static_branch_enable(&sched_schedstats);
else
static_branch_disable(&sched_schedstats);
}
void force_schedstat_enabled(void)
{
if (!schedstat_enabled()) {
pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
static_branch_enable(&sched_schedstats);
}
}
static int __init setup_schedstats(char *str)
{
int ret = 0;
if (!str) goto out;
if (!strcmp(str, "enable")) {
set_schedstats(true);
ret = 1;
} else if (!strcmp(str, "disable")) {
set_schedstats(false);
ret = 1;
}
out:
if (!ret)
pr_warn("Unable to parse schedstats=\n");
return ret;
}
__setup("schedstats=", setup_schedstats);
#ifdef CONFIG_PROC_SYSCTL
int sysctl_schedstats(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
struct ctl_table t;
int err;
int state = static_branch_likely(&sched_schedstats);
if (write && !capable(CAP_SYS_ADMIN))
return -EPERM;
t = *table;
t.data = &state;
err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
if (err < 0)
return err;
if (write)
set_schedstats(state);
return err;
}
#endif
#endif
/*
* fork()/clone()-time setup:
*/
int sched_fork(unsigned long clone_flags, struct task_struct *p)
{
unsigned long flags;
int cpu = get_cpu();
__sched_fork(clone_flags, p);
/*
* We mark the process as running here. This guarantees that
* nobody will actually run it, and a signal or other external
* event cannot wake it up and insert it on the runqueue either.
*/
p->state = TASK_RUNNING;
/*
* Make sure we do not leak PI boosting priority to the child.
*/
p->prio = current->normal_prio;
/*
* Revert to default priority/policy on fork if requested.
*/
if (unlikely(p->sched_reset_on_fork)) {
if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
p->policy = SCHED_NORMAL;
p->static_prio = NICE_TO_PRIO(0);
p->rt_priority = 0;
} else if (PRIO_TO_NICE(p->static_prio) < 0) p->static_prio = NICE_TO_PRIO(0);
p->prio = p->normal_prio = __normal_prio(p);
set_load_weight(p);
/*
* We don't need the reset flag anymore after the fork. It has
* fulfilled its duty:
*/
p->sched_reset_on_fork = 0;
}
if (dl_prio(p->prio)) {
put_cpu();
return -EAGAIN;
} else if (rt_prio(p->prio)) {
p->sched_class = &rt_sched_class;
} else {
p->sched_class = &fair_sched_class;
}
if (p->sched_class->task_fork)
p->sched_class->task_fork(p);
/*
* The child is not yet in the pid-hash so no cgroup attach races,
* and the cgroup is pinned to this child due to cgroup_fork()
* is ran before sched_fork().
*
* Silence PROVE_RCU.
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
set_task_cpu(p, cpu);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
#ifdef CONFIG_SCHED_INFO
if (likely(sched_info_on()))
memset(&p->sched_info, 0, sizeof(p->sched_info));
#endif
#if defined(CONFIG_SMP)
p->on_cpu = 0;
#endif
init_task_preempt_count(p);
#ifdef CONFIG_SMP
plist_node_init(&p->pushable_tasks, MAX_PRIO);
RB_CLEAR_NODE(&p->pushable_dl_tasks);
#endif
put_cpu();
return 0;
}
unsigned long to_ratio(u64 period, u64 runtime)
{
if (runtime == RUNTIME_INF)
return 1ULL << 20;
/*
* Doing this here saves a lot of checks in all
* the calling paths, and returning zero seems
* safe for them anyway.
*/
if (period == 0)
return 0;
return div64_u64(runtime << 20, period);
}
#ifdef CONFIG_SMP
inline struct dl_bw *dl_bw_of(int i){
RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
"sched RCU must be held");
return &cpu_rq(i)->rd->dl_bw;
}
static inline int dl_bw_cpus(int i)
{
struct root_domain *rd = cpu_rq(i)->rd;
int cpus = 0;
RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
"sched RCU must be held");
for_each_cpu_and(i, rd->span, cpu_active_mask)
cpus++;
return cpus;
}
#else
inline struct dl_bw *dl_bw_of(int i)
{
return &cpu_rq(i)->dl.dl_bw;
}
static inline int dl_bw_cpus(int i)
{
return 1;
}
#endif
/*
* 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.
*
* XXX we should delay bw change until the task's 0-lag point, see
* __setparam_dl().
*/
static int dl_overflow(struct task_struct *p, int policy,
const struct sched_attr *attr)
{
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
u64 period = attr->sched_period ?: attr->sched_deadline;
u64 runtime = attr->sched_runtime;
u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
int cpus, err = -1;
if (new_bw == p->dl.dl_bw)
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)) {
__dl_add(dl_b, new_bw);
err = 0;
} else if (dl_policy(policy) && task_has_dl_policy(p) &&
!__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
__dl_clear(dl_b, p->dl.dl_bw);
__dl_add(dl_b, new_bw);
err = 0; } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
__dl_clear(dl_b, p->dl.dl_bw);
err = 0;
}
raw_spin_unlock(&dl_b->lock);
return err;
}
extern void init_dl_bw(struct dl_bw *dl_b);
/*
* wake_up_new_task - wake up a newly created task for the first time.
*
* This function will do some initial scheduler statistics housekeeping
* that must be done for every newly created context, then puts the task
* on the runqueue and wakes it.
*/
void wake_up_new_task(struct task_struct *p)
{
unsigned long flags;
struct rq *rq;
raw_spin_lock_irqsave(&p->pi_lock, flags);
/* Initialize new task's runnable average */
init_entity_runnable_average(&p->se);
#ifdef CONFIG_SMP
/*
* Fork balancing, do it here and not earlier because:
* - cpus_allowed can change in the fork path
* - any previously selected cpu might disappear through hotplug
*/
set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
#endif
rq = __task_rq_lock(p);
activate_task(rq, p, 0);
p->on_rq = TASK_ON_RQ_QUEUED;
trace_sched_wakeup_new(p);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
if (p->sched_class->task_woken) {
/*
* Nothing relies on rq->lock after this, so its fine to
* drop it.
*/
lockdep_unpin_lock(&rq->lock);
p->sched_class->task_woken(rq, p);
lockdep_pin_lock(&rq->lock);
}
#endif
task_rq_unlock(rq, p, &flags);
}
#ifdef CONFIG_PREEMPT_NOTIFIERS
static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
void preempt_notifier_inc(void)
{
static_key_slow_inc(&preempt_notifier_key);
}
EXPORT_SYMBOL_GPL(preempt_notifier_inc);
void preempt_notifier_dec(void)
{
static_key_slow_dec(&preempt_notifier_key);
}
EXPORT_SYMBOL_GPL(preempt_notifier_dec);
/**
* preempt_notifier_register - tell me when current is being preempted & rescheduled
* @notifier: notifier struct to register
*/
void preempt_notifier_register(struct preempt_notifier *notifier)
{
if (!static_key_false(&preempt_notifier_key))
WARN(1, "registering preempt_notifier while notifiers disabled\n");
hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
}
EXPORT_SYMBOL_GPL(preempt_notifier_register);
/**
* preempt_notifier_unregister - no longer interested in preemption notifications
* @notifier: notifier struct to unregister
*
* This is *not* safe to call from within a preemption notifier.
*/
void preempt_notifier_unregister(struct preempt_notifier *notifier)
{
hlist_del(¬ifier->link);
}
EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
{
struct preempt_notifier *notifier;
hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
notifier->ops->sched_in(notifier, raw_smp_processor_id());
}
static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
{
if (static_key_false(&preempt_notifier_key))
__fire_sched_in_preempt_notifiers(curr);
}
static void
__fire_sched_out_preempt_notifiers(struct task_struct *curr,
struct task_struct *next)
{
struct preempt_notifier *notifier;
hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
notifier->ops->sched_out(notifier, next);
}
static __always_inline void
fire_sched_out_preempt_notifiers(struct task_struct *curr,
struct task_struct *next)
{
if (static_key_false(&preempt_notifier_key))
__fire_sched_out_preempt_notifiers(curr, next);
}
#else /* !CONFIG_PREEMPT_NOTIFIERS */
static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
{
}
static inline void
fire_sched_out_preempt_notifiers(struct task_struct *curr,
struct task_struct *next)
{
}
#endif /* CONFIG_PREEMPT_NOTIFIERS */
/**
* prepare_task_switch - prepare to switch tasks
* @rq: the runqueue preparing to switch
* @prev: the current task that is being switched out
* @next: the task we are going to switch to.
*
* This is called with the rq lock held and interrupts off. It must
* be paired with a subsequent finish_task_switch after the context
* switch.
*
* prepare_task_switch sets up locking and calls architecture specific
* hooks.
*/
static inline void
prepare_task_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
sched_info_switch(rq, prev, next);
perf_event_task_sched_out(prev, next);
fire_sched_out_preempt_notifiers(prev, next);
prepare_lock_switch(rq, next);
prepare_arch_switch(next);
}
/**
* finish_task_switch - clean up after a task-switch
* @prev: the thread we just switched away from.
*
* finish_task_switch must be called after the context switch, paired
* with a prepare_task_switch call before the context switch.
* finish_task_switch will reconcile locking set up by prepare_task_switch,
* and do any other architecture-specific cleanup actions.
*
* Note that we may have delayed dropping an mm in context_switch(). If
* so, we finish that here outside of the runqueue lock. (Doing it
* with the lock held can cause deadlocks; see schedule() for
* details.)
*
* The context switch have flipped the stack from under us and restored the
* local variables which were saved when this task called schedule() in the
* past. prev == current is still correct but we need to recalculate this_rq
* because prev may have moved to another CPU.
*/
static struct rq *finish_task_switch(struct task_struct *prev)
__releases(rq->lock)
{
struct rq *rq = this_rq();
struct mm_struct *mm = rq->prev_mm;
long prev_state;
/*
* The previous task will have left us with a preempt_count of 2
* because it left us after:
*
* schedule()
* preempt_disable(); // 1
* __schedule()
* raw_spin_lock_irq(&rq->lock) // 2
*
* Also, see FORK_PREEMPT_COUNT.
*/
if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
"corrupted preempt_count: %s/%d/0x%x\n",
current->comm, current->pid, preempt_count()))
preempt_count_set(FORK_PREEMPT_COUNT);
rq->prev_mm = NULL;
/* * A task struct has one reference for the use as "current".
* If a task dies, then it sets TASK_DEAD in tsk->state and calls
* schedule one last time. The schedule call will never return, and
* the scheduled task must drop that reference.
*
* We must observe prev->state before clearing prev->on_cpu (in
* finish_lock_switch), otherwise a concurrent wakeup can get prev
* running on another CPU and we could rave with its RUNNING -> DEAD
* transition, resulting in a double drop.
*/
prev_state = prev->state;
vtime_task_switch(prev);
perf_event_task_sched_in(prev, current);
finish_lock_switch(rq, prev);
finish_arch_post_lock_switch();
fire_sched_in_preempt_notifiers(current);
if (mm)
mmdrop(mm);
if (unlikely(prev_state == TASK_DEAD)) {
if (prev->sched_class->task_dead)
prev->sched_class->task_dead(prev);
/*
* Remove function-return probe instances associated with this
* task and put them back on the free list.
*/
kprobe_flush_task(prev);
put_task_struct(prev);
}
tick_nohz_task_switch();
return rq;
}
#ifdef CONFIG_SMP
/* rq->lock is NOT held, but preemption is disabled */
static void __balance_callback(struct rq *rq)
{
struct callback_head *head, *next;
void (*func)(struct rq *rq);
unsigned long flags;
raw_spin_lock_irqsave(&rq->lock, flags);
head = rq->balance_callback;
rq->balance_callback = NULL;
while (head) {
func = (void (*)(struct rq *))head->func;
next = head->next;
head->next = NULL;
head = next;
func(rq);
}
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
static inline void balance_callback(struct rq *rq)
{
if (unlikely(rq->balance_callback))
__balance_callback(rq);
}
#else
static inline void balance_callback(struct rq *rq)
{
}
#endif
/**
* schedule_tail - first thing a freshly forked thread must call.
* @prev: the thread we just switched away from.
*/
asmlinkage __visible void schedule_tail(struct task_struct *prev)
__releases(rq->lock)
{
struct rq *rq;
/*
* New tasks start with FORK_PREEMPT_COUNT, see there and
* finish_task_switch() for details.
*
* finish_task_switch() will drop rq->lock() and lower preempt_count
* and the preempt_enable() will end up enabling preemption (on
* PREEMPT_COUNT kernels).
*/
rq = finish_task_switch(prev);
balance_callback(rq);
preempt_enable();
if (current->set_child_tid)
put_user(task_pid_vnr(current), current->set_child_tid);
}
/*
* context_switch - switch to the new MM and the new thread's register state.
*/
static inline struct rq *
context_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
struct mm_struct *mm, *oldmm;
prepare_task_switch(rq, prev, next);
mm = next->mm;
oldmm = prev->active_mm;
/*
* For paravirt, this is coupled with an exit in switch_to to
* combine the page table reload and the switch backend into
* one hypercall.
*/
arch_start_context_switch(prev);
if (!mm) {
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next);
} else
switch_mm(oldmm, mm, next);
if (!prev->mm) {
prev->active_mm = NULL;
rq->prev_mm = oldmm;
}
/*
* Since the runqueue lock will be released by the next
* task (which is an invalid locking op but in the case
* of the scheduler it's an obvious special-case), so we
* do an early lockdep release here:
*/
lockdep_unpin_lock(&rq->lock);
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
/* Here we just switch the register state and the stack. */
switch_to(prev, next, prev); barrier();
return finish_task_switch(prev);
}
/*
* nr_running and nr_context_switches:
*
* externally visible scheduler statistics: current number of runnable
* threads, total number of context switches performed since bootup.
*/
unsigned long nr_running(void)
{
unsigned long i, sum = 0;
for_each_online_cpu(i)
sum += cpu_rq(i)->nr_running;
return sum;
}
/*
* Check if only the current task is running on the cpu.
*
* Caution: this function does not check that the caller has disabled
* preemption, thus the result might have a time-of-check-to-time-of-use
* race. The caller is responsible to use it correctly, for example:
*
* - from a non-preemptable section (of course)
*
* - from a thread that is bound to a single CPU
*
* - in a loop with very short iterations (e.g. a polling loop)
*/
bool single_task_running(void)
{
return raw_rq()->nr_running == 1;
}
EXPORT_SYMBOL(single_task_running);
unsigned long long nr_context_switches(void)
{
int i;
unsigned long long sum = 0;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_switches;
return sum;
}
unsigned long nr_iowait(void)
{
unsigned long i, sum = 0;
for_each_possible_cpu(i)
sum += atomic_read(&cpu_rq(i)->nr_iowait);
return sum;
}
unsigned long nr_iowait_cpu(int cpu)
{
struct rq *this = cpu_rq(cpu);
return atomic_read(&this->nr_iowait);
}
void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
{
struct rq *rq = this_rq(); *nr_waiters = atomic_read(&rq->nr_iowait);
*load = rq->load.weight;
}
#ifdef CONFIG_SMP
/*
* sched_exec - execve() is a valuable balancing opportunity, because at
* this point the task has the smallest effective memory and cache footprint.
*/
void sched_exec(void)
{
struct task_struct *p = current;
unsigned long flags;
int dest_cpu;
raw_spin_lock_irqsave(&p->pi_lock, flags);
dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
if (dest_cpu == smp_processor_id())
goto unlock;
if (likely(cpu_active(dest_cpu))) {
struct migration_arg arg = { p, dest_cpu };
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
return;
}
unlock:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
}
#endif
DEFINE_PER_CPU(struct kernel_stat, kstat);
DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
EXPORT_PER_CPU_SYMBOL(kstat);
EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
/*
* Return accounted runtime for the task.
* In case the task is currently running, return the runtime plus current's
* pending runtime that have not been accounted yet.
*/
unsigned long long task_sched_runtime(struct task_struct *p)
{
unsigned long flags;
struct rq *rq;
u64 ns;
#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
/*
* 64-bit doesn't need locks to atomically read a 64bit value.
* So we have a optimization chance when the task's delta_exec is 0.
* Reading ->on_cpu is racy, but this is ok.
*
* If we race with it leaving cpu, we'll take a lock. So we're correct.
* If we race with it entering cpu, unaccounted time is 0. This is
* indistinguishable from the read occurring a few cycles earlier.
* If we see ->on_cpu without ->on_rq, the task is leaving, and has
* been accounted, so we're correct here as well.
*/
if (!p->on_cpu || !task_on_rq_queued(p))
return p->se.sum_exec_runtime;
#endif
rq = task_rq_lock(p, &flags);
/*
* Must be ->curr _and_ ->on_rq. If dequeued, we would * project cycles that may never be accounted to this
* thread, breaking clock_gettime().
*/
if (task_current(rq, p) && task_on_rq_queued(p)) {
update_rq_clock(rq);
p->sched_class->update_curr(rq);
}
ns = p->se.sum_exec_runtime;
task_rq_unlock(rq, p, &flags);
return ns;
}
/*
* This function gets called by the timer code, with HZ frequency.
* We call it with interrupts disabled.
*/
void scheduler_tick(void)
{
int cpu = smp_processor_id();
struct rq *rq = cpu_rq(cpu);
struct task_struct *curr = rq->curr;
sched_clock_tick();
raw_spin_lock(&rq->lock);
update_rq_clock(rq);
curr->sched_class->task_tick(rq, curr, 0);
update_cpu_load_active(rq);
calc_global_load_tick(rq);
raw_spin_unlock(&rq->lock);
perf_event_task_tick();
#ifdef CONFIG_SMP
rq->idle_balance = idle_cpu(cpu);
trigger_load_balance(rq);
#endif
rq_last_tick_reset(rq);
}
#ifdef CONFIG_NO_HZ_FULL
/**
* scheduler_tick_max_deferment
*
* Keep at least one tick per second when a single
* active task is running because the scheduler doesn't
* yet completely support full dynticks environment.
*
* This makes sure that uptime, CFS vruntime, load
* balancing, etc... continue to move forward, even
* with a very low granularity.
*
* Return: Maximum deferment in nanoseconds.
*/
u64 scheduler_tick_max_deferment(void)
{
struct rq *rq = this_rq();
unsigned long next, now = READ_ONCE(jiffies);
next = rq->last_sched_tick + HZ;
if (time_before_eq(next, now))
return 0;
return jiffies_to_nsecs(next - now);
}
#endif
#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ defined(CONFIG_PREEMPT_TRACER))
void preempt_count_add(int val)
{
#ifdef CONFIG_DEBUG_PREEMPT
/*
* Underflow?
*/
if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
return;
#endif
__preempt_count_add(val);
#ifdef CONFIG_DEBUG_PREEMPT
/*
* Spinlock count overflowing soon?
*/
DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
PREEMPT_MASK - 10);
#endif
if (preempt_count() == val) {
unsigned long ip = get_lock_parent_ip();
#ifdef CONFIG_DEBUG_PREEMPT
current->preempt_disable_ip = ip;
#endif
trace_preempt_off(CALLER_ADDR0, ip);
}
}
EXPORT_SYMBOL(preempt_count_add);
NOKPROBE_SYMBOL(preempt_count_add);
void preempt_count_sub(int val)
{
#ifdef CONFIG_DEBUG_PREEMPT
/*
* Underflow?
*/
if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
return;
/*
* Is the spinlock portion underflowing?
*/
if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
!(preempt_count() & PREEMPT_MASK)))
return;
#endif
if (preempt_count() == val)
trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
__preempt_count_sub(val);
}
EXPORT_SYMBOL(preempt_count_sub);
NOKPROBE_SYMBOL(preempt_count_sub);
#endif
/*
* Print scheduling while atomic bug:
*/
static noinline void __schedule_bug(struct task_struct *prev)
{
if (oops_in_progress)
return;
printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
prev->comm, prev->pid, preempt_count());
debug_show_held_locks(prev);
print_modules();
if (irqs_disabled())
print_irqtrace_events(prev);#ifdef CONFIG_DEBUG_PREEMPT
if (in_atomic_preempt_off()) {
pr_err("Preemption disabled at:");
print_ip_sym(current->preempt_disable_ip);
pr_cont("\n");
}
#endif
dump_stack();
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
}
/*
* Various schedule()-time debugging checks and statistics:
*/
static inline void schedule_debug(struct task_struct *prev)
{
#ifdef CONFIG_SCHED_STACK_END_CHECK
BUG_ON(task_stack_end_corrupted(prev));
#endif
if (unlikely(in_atomic_preempt_off())) {
__schedule_bug(prev);
preempt_count_set(PREEMPT_DISABLED);
}
rcu_sleep_check();
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
schedstat_inc(this_rq(), sched_count);
}
/*
* Pick up the highest-prio task:
*/
static inline struct task_struct *
pick_next_task(struct rq *rq, struct task_struct *prev)
{
const struct sched_class *class = &fair_sched_class;
struct task_struct *p;
/*
* Optimization: we know that if all tasks are in
* the fair class we can call that function directly:
*/
if (likely(prev->sched_class == class &&
rq->nr_running == rq->cfs.h_nr_running)) {
p = fair_sched_class.pick_next_task(rq, prev);
if (unlikely(p == RETRY_TASK))
goto again;
/* assumes fair_sched_class->next == idle_sched_class */
if (unlikely(!p))
p = idle_sched_class.pick_next_task(rq, prev);
return p;
}
again:
for_each_class(class) {
p = class->pick_next_task(rq, prev);
if (p) {
if (unlikely(p == RETRY_TASK))
goto again;
return p;
}
}
BUG(); /* the idle class will always have a runnable task */
}
/*
* __schedule() is the main scheduler function.
*
* The main means of driving the scheduler and thus entering this function are:
*
* 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
*
* 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
* paths. For example, see arch/x86/entry_64.S.
*
* To drive preemption between tasks, the scheduler sets the flag in timer
* interrupt handler scheduler_tick().
*
* 3. Wakeups don't really cause entry into schedule(). They add a
* task to the run-queue and that's it.
*
* Now, if the new task added to the run-queue preempts the current
* task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
* called on the nearest possible occasion:
*
* - If the kernel is preemptible (CONFIG_PREEMPT=y):
*
* - in syscall or exception context, at the next outmost
* preempt_enable(). (this might be as soon as the wake_up()'s
* spin_unlock()!)
*
* - in IRQ context, return from interrupt-handler to
* preemptible context
*
* - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
* then at the next:
*
* - cond_resched() call
* - explicit schedule() call
* - return from syscall or exception to user-space
* - return from interrupt-handler to user-space
*
* WARNING: must be called with preemption disabled!
*/
static void __sched notrace __schedule(bool preempt)
{
struct task_struct *prev, *next;
unsigned long *switch_count;
struct rq *rq;
int cpu;
cpu = smp_processor_id();
rq = cpu_rq(cpu);
prev = rq->curr;
/*
* do_exit() calls schedule() with preemption disabled as an exception;
* however we must fix that up, otherwise the next task will see an
* inconsistent (higher) preempt count.
*
* It also avoids the below schedule_debug() test from complaining
* about this.
*/
if (unlikely(prev->state == TASK_DEAD))
preempt_enable_no_resched_notrace();
schedule_debug(prev);
if (sched_feat(HRTICK))
hrtick_clear(rq);
local_irq_disable();
rcu_note_context_switch();
/* * Make sure that signal_pending_state()->signal_pending() below
* can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
* done by the caller to avoid the race with signal_wake_up().
*/
smp_mb__before_spinlock();
raw_spin_lock(&rq->lock);
lockdep_pin_lock(&rq->lock);
rq->clock_skip_update <<= 1; /* promote REQ to ACT */
switch_count = &prev->nivcsw;
if (!preempt && prev->state) {
if (unlikely(signal_pending_state(prev->state, prev))) {
prev->state = TASK_RUNNING;
} else {
deactivate_task(rq, prev, DEQUEUE_SLEEP);
prev->on_rq = 0;
/*
* If a worker went to sleep, notify and ask workqueue
* whether it wants to wake up a task to maintain
* concurrency.
*/
if (prev->flags & PF_WQ_WORKER) {
struct task_struct *to_wakeup;
to_wakeup = wq_worker_sleeping(prev);
if (to_wakeup)
try_to_wake_up_local(to_wakeup);
}
}
switch_count = &prev->nvcsw;
}
if (task_on_rq_queued(prev))
update_rq_clock(rq);
next = pick_next_task(rq, prev);
clear_tsk_need_resched(prev);
clear_preempt_need_resched();
rq->clock_skip_update = 0;
if (likely(prev != next)) {
rq->nr_switches++;
rq->curr = next;
++*switch_count;
trace_sched_switch(preempt, prev, next);
rq = context_switch(rq, prev, next); /* unlocks the rq */
} else {
lockdep_unpin_lock(&rq->lock);
raw_spin_unlock_irq(&rq->lock);
}
balance_callback(rq);
}
static inline void sched_submit_work(struct task_struct *tsk)
{
if (!tsk->state || tsk_is_pi_blocked(tsk))
return;
/*
* If we are going to sleep and we have plugged IO queued,
* make sure to submit it to avoid deadlocks.
*/
if (blk_needs_flush_plug(tsk))
blk_schedule_flush_plug(tsk);
}
asmlinkage __visible void __sched schedule(void){
struct task_struct *tsk = current;
sched_submit_work(tsk);
do {
preempt_disable();
__schedule(false);
sched_preempt_enable_no_resched();
} while (need_resched());
}
EXPORT_SYMBOL(schedule);
#ifdef CONFIG_CONTEXT_TRACKING
asmlinkage __visible void __sched schedule_user(void)
{
/*
* If we come here after a random call to set_need_resched(),
* or we have been woken up remotely but the IPI has not yet arrived,
* we haven't yet exited the RCU idle mode. Do it here manually until
* we find a better solution.
*
* NB: There are buggy callers of this function. Ideally we
* should warn if prev_state != CONTEXT_USER, but that will trigger
* too frequently to make sense yet.
*/
enum ctx_state prev_state = exception_enter();
schedule();
exception_exit(prev_state);
}
#endif
/**
* schedule_preempt_disabled - called with preemption disabled
*
* Returns with preemption disabled. Note: preempt_count must be 1
*/
void __sched schedule_preempt_disabled(void)
{
sched_preempt_enable_no_resched();
schedule();
preempt_disable();
}
static void __sched notrace preempt_schedule_common(void)
{
do {
preempt_disable_notrace();
__schedule(true);
preempt_enable_no_resched_notrace();
/*
* Check again in case we missed a preemption opportunity
* between schedule and now.
*/
} while (need_resched());
}
#ifdef CONFIG_PREEMPT
/*
* this is the entry point to schedule() from in-kernel preemption
* off of preempt_enable. Kernel preemptions off return from interrupt
* occur there and call schedule directly.
*/
asmlinkage __visible void __sched notrace preempt_schedule(void)
{
/*
* If there is a non-zero preempt_count or interrupts are disabled,
* we do not want to preempt the current task. Just return..
*/
if (likely(!preemptible())) return;
preempt_schedule_common();
}
NOKPROBE_SYMBOL(preempt_schedule);
EXPORT_SYMBOL(preempt_schedule);
/**
* preempt_schedule_notrace - preempt_schedule called by tracing
*
* The tracing infrastructure uses preempt_enable_notrace to prevent
* recursion and tracing preempt enabling caused by the tracing
* infrastructure itself. But as tracing can happen in areas coming
* from userspace or just about to enter userspace, a preempt enable
* can occur before user_exit() is called. This will cause the scheduler
* to be called when the system is still in usermode.
*
* To prevent this, the preempt_enable_notrace will use this function
* instead of preempt_schedule() to exit user context if needed before
* calling the scheduler.
*/
asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
{
enum ctx_state prev_ctx;
if (likely(!preemptible()))
return;
do {
preempt_disable_notrace();
/*
* Needs preempt disabled in case user_exit() is traced
* and the tracer calls preempt_enable_notrace() causing
* an infinite recursion.
*/
prev_ctx = exception_enter();
__schedule(true);
exception_exit(prev_ctx);
preempt_enable_no_resched_notrace();
} while (need_resched());
}
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
#endif /* CONFIG_PREEMPT */
/*
* this is the entry point to schedule() from kernel preemption
* off of irq context.
* Note, that this is called and return with irqs disabled. This will
* protect us against recursive calling from irq.
*/
asmlinkage __visible void __sched preempt_schedule_irq(void)
{
enum ctx_state prev_state;
/* Catch callers which need to be fixed */
BUG_ON(preempt_count() || !irqs_disabled());
prev_state = exception_enter();
do {
preempt_disable();
local_irq_enable();
__schedule(true);
local_irq_disable();
sched_preempt_enable_no_resched();
} while (need_resched());
exception_exit(prev_state);}
int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
void *key)
{
return try_to_wake_up(curr->private, mode, wake_flags);
}
EXPORT_SYMBOL(default_wake_function);
#ifdef CONFIG_RT_MUTEXES
/*
* rt_mutex_setprio - set the current priority of a task
* @p: task
* @prio: prio value (kernel-internal form)
*
* This function changes the 'effective' priority of a task. It does
* not touch ->normal_prio like __setscheduler().
*
* Used by the rt_mutex code to implement priority inheritance
* logic. Call site only calls if the priority of the task changed.
*/
void rt_mutex_setprio(struct task_struct *p, int prio)
{
int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
struct rq *rq;
const struct sched_class *prev_class;
BUG_ON(prio > MAX_PRIO);
rq = __task_rq_lock(p);
/*
* Idle task boosting is a nono in general. There is one
* exception, when PREEMPT_RT and NOHZ is active:
*
* The idle task calls get_next_timer_interrupt() and holds
* the timer wheel base->lock on the CPU and another CPU wants
* to access the timer (probably to cancel it). We can safely
* ignore the boosting request, as the idle CPU runs this code
* with interrupts disabled and will complete the lock
* protected section without being interrupted. So there is no
* real need to boost.
*/
if (unlikely(p == rq->idle)) {
WARN_ON(p != rq->curr);
WARN_ON(p->pi_blocked_on);
goto out_unlock;
}
trace_sched_pi_setprio(p, prio);
oldprio = p->prio;
if (oldprio == prio)
queue_flag &= ~DEQUEUE_MOVE;
prev_class = p->sched_class;
queued = task_on_rq_queued(p);
running = task_current(rq, p);
if (queued)
dequeue_task(rq, p, queue_flag);
if (running)
put_prev_task(rq, p);
/*
* Boosting condition are:
* 1. -rt task is running and holds mutex A
* --> -dl task blocks on mutex A
*
* 2. -dl task is running and holds mutex A * --> -dl task blocks on mutex A and could preempt the
* running task
*/
if (dl_prio(prio)) {
struct task_struct *pi_task = rt_mutex_get_top_task(p);
if (!dl_prio(p->normal_prio) ||
(pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
p->dl.dl_boosted = 1;
queue_flag |= ENQUEUE_REPLENISH;
} else
p->dl.dl_boosted = 0;
p->sched_class = &dl_sched_class;
} else if (rt_prio(prio)) {
if (dl_prio(oldprio))
p->dl.dl_boosted = 0;
if (oldprio < prio)
queue_flag |= ENQUEUE_HEAD;
p->sched_class = &rt_sched_class;
} else {
if (dl_prio(oldprio))
p->dl.dl_boosted = 0;
if (rt_prio(oldprio))
p->rt.timeout = 0;
p->sched_class = &fair_sched_class;
}
p->prio = prio;
if (running)
p->sched_class->set_curr_task(rq);
if (queued)
enqueue_task(rq, p, queue_flag);
check_class_changed(rq, p, prev_class, oldprio);
out_unlock:
preempt_disable(); /* avoid rq from going away on us */
__task_rq_unlock(rq);
balance_callback(rq);
preempt_enable();
}
#endif
void set_user_nice(struct task_struct *p, long nice)
{
int old_prio, delta, queued;
unsigned long flags;
struct rq *rq;
if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
return;
/*
* We have to be careful, if called from sys_setpriority(),
* the task might be in the middle of scheduling on another CPU.
*/
rq = task_rq_lock(p, &flags);
/*
* The RT priorities are set via sched_setscheduler(), but we still
* allow the 'normal' nice value to be set - but as expected
* it wont have any effect on scheduling until the task is
* SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
*/
if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
p->static_prio = NICE_TO_PRIO(nice);
goto out_unlock;
}
queued = task_on_rq_queued(p);
if (queued)
dequeue_task(rq, p, DEQUEUE_SAVE);
p->static_prio = NICE_TO_PRIO(nice);
set_load_weight(p);
old_prio = p->prio;
p->prio = effective_prio(p);
delta = p->prio - old_prio;
if (queued) {
enqueue_task(rq, p, ENQUEUE_RESTORE);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
*/
if (delta < 0 || (delta > 0 && task_running(rq, p)))
resched_curr(rq);
}
out_unlock:
task_rq_unlock(rq, p, &flags);
}
EXPORT_SYMBOL(set_user_nice);
/*
* can_nice - check if a task can reduce its nice value
* @p: task
* @nice: nice value
*/
int can_nice(const struct task_struct *p, const int nice)
{
/* convert nice value [19,-20] to rlimit style value [1,40] */
int nice_rlim = nice_to_rlimit(nice);
return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
capable(CAP_SYS_NICE));
}
#ifdef __ARCH_WANT_SYS_NICE
/*
* sys_nice - change the priority of the current process.
* @increment: priority increment
*
* sys_setpriority is a more generic, but much slower function that
* does similar things.
*/
SYSCALL_DEFINE1(nice, int, increment)
{
long nice, retval;
/*
* Setpriority might change our priority at the same moment.
* We don't have to worry. Conceptually one call occurs first
* and we have a single winner.
*/
increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
nice = task_nice(current) + increment;
nice = clamp_val(nice, MIN_NICE, MAX_NICE);
if (increment < 0 && !can_nice(current, nice))
return -EPERM;
retval = security_task_setnice(current, nice);
if (retval)
return retval;
set_user_nice(current, nice);
return 0;
}
#endif
/** * task_prio - return the priority value of a given task.
* @p: the task in question.
*
* Return: The priority value as seen by users in /proc.
* RT tasks are offset by -200. Normal tasks are centered
* around 0, value goes from -16 to +15.
*/
int task_prio(const struct task_struct *p)
{
return p->prio - MAX_RT_PRIO;
}
/**
* idle_cpu - is a given cpu idle currently?
* @cpu: the processor in question.
*
* Return: 1 if the CPU is currently idle. 0 otherwise.
*/
int idle_cpu(int cpu)
{
struct rq *rq = cpu_rq(cpu);
if (rq->curr != rq->idle)
return 0;
if (rq->nr_running)
return 0;
#ifdef CONFIG_SMP
if (!llist_empty(&rq->wake_list))
return 0;
#endif
return 1;
}
/**
* idle_task - return the idle task for a given cpu.
* @cpu: the processor in question.
*
* Return: The idle task for the cpu @cpu.
*/
struct task_struct *idle_task(int cpu)
{
return cpu_rq(cpu)->idle;
}
/**
* find_process_by_pid - find a process with a matching PID value.
* @pid: the pid in question.
*
* The task of @pid, if found. %NULL otherwise.
*/
static struct task_struct *find_process_by_pid(pid_t pid)
{
return pid ? find_task_by_vpid(pid) : current;
}
/*
* 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.
*/
static 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);
/*
* Changing the parameters of a task is 'tricky' and we're not doing
* the correct thing -- also see task_dead_dl() and switched_from_dl().
*
* What we SHOULD do is delay the bandwidth release until the 0-lag
* point. This would include retaining the task_struct until that time
* and change dl_overflow() to not immediately decrement the current
* amount.
*
* Instead we retain the current runtime/deadline and let the new
* parameters take effect after the current reservation period lapses.
* This is safe (albeit pessimistic) because the 0-lag point is always
* before the current scheduling deadline.
*
* We can still have temporary overloads because we do not delay the
* change in bandwidth until that time; so admission control is
* not on the safe side. It does however guarantee tasks will never
* consume more than promised.
*/
}
/*
* sched_setparam() passes in -1 for its policy, to let the functions
* it calls know not to change it.
*/
#define SETPARAM_POLICY -1
static void __setscheduler_params(struct task_struct *p,
const struct sched_attr *attr)
{
int policy = attr->sched_policy;
if (policy == SETPARAM_POLICY)
policy = p->policy;
p->policy = policy;
if (dl_policy(policy))
__setparam_dl(p, attr);
else if (fair_policy(policy))
p->static_prio = NICE_TO_PRIO(attr->sched_nice);
/*
* __sched_setscheduler() ensures attr->sched_priority == 0 when
* !rt_policy. Always setting this ensures that things like
* getparam()/getattr() don't report silly values for !rt tasks.
*/
p->rt_priority = attr->sched_priority;
p->normal_prio = normal_prio(p);
set_load_weight(p);
}
/* Actually do priority change: must hold pi & rq lock. */
static void __setscheduler(struct rq *rq, struct task_struct *p,
const struct sched_attr *attr, bool keep_boost)
{
__setscheduler_params(p, attr);
/*
* Keep a potential priority boosting if called from
* sched_setscheduler().
*/
if (keep_boost) p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
else
p->prio = normal_prio(p);
if (dl_prio(p->prio))
p->sched_class = &dl_sched_class;
else if (rt_prio(p->prio))
p->sched_class = &rt_sched_class;
else
p->sched_class = &fair_sched_class;
}
static 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).
*/
static 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;
}
/*
* check the target process has a UID that matches the current process's
*/
static bool check_same_owner(struct task_struct *p)
{ const struct cred *cred = current_cred(), *pcred;
bool match;
rcu_read_lock();
pcred = __task_cred(p);
match = (uid_eq(cred->euid, pcred->euid) ||
uid_eq(cred->euid, pcred->uid));
rcu_read_unlock();
return match;
}
static 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;
}
static int __sched_setscheduler(struct task_struct *p,
const struct sched_attr *attr,
bool user, bool pi)
{
int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
MAX_RT_PRIO - 1 - attr->sched_priority;
int retval, oldprio, oldpolicy = -1, queued, running;
int new_effective_prio, policy = attr->sched_policy;
unsigned long flags;
const struct sched_class *prev_class;
struct rq *rq;
int reset_on_fork;
int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
/* may grab non-irq protected spin_locks */
BUG_ON(in_interrupt());
recheck:
/* double check policy once rq lock held */
if (policy < 0) {
reset_on_fork = p->sched_reset_on_fork;
policy = oldpolicy = p->policy;
} else {
reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
if (!valid_policy(policy))
return -EINVAL;
}
if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
return -EINVAL;
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are
* 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
* SCHED_BATCH and SCHED_IDLE is 0.
*/
if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
(!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
return -EINVAL;
if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
(rt_policy(policy) != (attr->sched_priority != 0)))
return -EINVAL;
/*
* Allow unprivileged RT tasks to decrease priority: */
if (user && !capable(CAP_SYS_NICE)) {
if (fair_policy(policy)) {
if (attr->sched_nice < task_nice(p) &&
!can_nice(p, attr->sched_nice))
return -EPERM;
}
if (rt_policy(policy)) {
unsigned long rlim_rtprio =
task_rlimit(p, RLIMIT_RTPRIO);
/* can't set/change the rt policy */
if (policy != p->policy && !rlim_rtprio)
return -EPERM;
/* can't increase priority */
if (attr->sched_priority > p->rt_priority &&
attr->sched_priority > rlim_rtprio)
return -EPERM;
}
/*
* Can't set/change SCHED_DEADLINE policy at all for now
* (safest behavior); in the future we would like to allow
* unprivileged DL tasks to increase their relative deadline
* or reduce their runtime (both ways reducing utilization)
*/
if (dl_policy(policy))
return -EPERM;
/*
* Treat SCHED_IDLE as nice 20. Only allow a switch to
* SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
*/
if (idle_policy(p->policy) && !idle_policy(policy)) {
if (!can_nice(p, task_nice(p)))
return -EPERM;
}
/* can't change other user's priorities */
if (!check_same_owner(p))
return -EPERM;
/* Normal users shall not reset the sched_reset_on_fork flag */
if (p->sched_reset_on_fork && !reset_on_fork)
return -EPERM;
}
if (user) {
retval = security_task_setscheduler(p);
if (retval)
return retval;
}
/*
* make sure no PI-waiters arrive (or leave) while we are
* changing the priority of the task:
*
* To be able to change p->policy safely, the appropriate
* runqueue lock must be held.
*/
rq = task_rq_lock(p, &flags);
/*
* Changing the policy of the stop threads its a very bad idea
*/
if (p == rq->stop) {
task_rq_unlock(rq, p, &flags);
return -EINVAL; }
/*
* If not changing anything there's no need to proceed further,
* but store a possible modification of reset_on_fork.
*/
if (unlikely(policy == p->policy)) {
if (fair_policy(policy) && attr->sched_nice != task_nice(p))
goto change;
if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
goto change;
if (dl_policy(policy) && dl_param_changed(p, attr))
goto change;
p->sched_reset_on_fork = reset_on_fork;
task_rq_unlock(rq, p, &flags);
return 0;
}
change:
if (user) {
#ifdef CONFIG_RT_GROUP_SCHED
/*
* Do not allow realtime tasks into groups that have no runtime
* assigned.
*/
if (rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0 &&
!task_group_is_autogroup(task_group(p))) {
task_rq_unlock(rq, p, &flags);
return -EPERM;
}
#endif
#ifdef CONFIG_SMP
if (dl_bandwidth_enabled() && dl_policy(policy)) {
cpumask_t *span = rq->rd->span;
/*
* Don't allow tasks with an affinity mask smaller than
* the entire root_domain to become SCHED_DEADLINE. We
* will also fail if there's no bandwidth available.
*/
if (!cpumask_subset(span, &p->cpus_allowed) ||
rq->rd->dl_bw.bw == 0) {
task_rq_unlock(rq, p, &flags);
return -EPERM;
}
}
#endif
}
/* recheck policy now with rq lock held */
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
policy = oldpolicy = -1;
task_rq_unlock(rq, p, &flags);
goto recheck;
}
/*
* If setscheduling to SCHED_DEADLINE (or changing the parameters
* of a SCHED_DEADLINE task) we need to check if enough bandwidth
* is available.
*/
if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
task_rq_unlock(rq, p, &flags);
return -EBUSY;
}
p->sched_reset_on_fork = reset_on_fork;
oldprio = p->prio;
if (pi) {
/*
* Take priority boosted tasks into account. If the new
* effective priority is unchanged, we just store the new
* normal parameters and do not touch the scheduler class and
* the runqueue. This will be done when the task deboost
* itself.
*/
new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
if (new_effective_prio == oldprio)
queue_flags &= ~DEQUEUE_MOVE;
}
queued = task_on_rq_queued(p);
running = task_current(rq, p);
if (queued)
dequeue_task(rq, p, queue_flags);
if (running)
put_prev_task(rq, p);
prev_class = p->sched_class;
__setscheduler(rq, p, attr, pi);
if (running)
p->sched_class->set_curr_task(rq);
if (queued) {
/*
* We enqueue to tail when the priority of a task is
* increased (user space view).
*/
if (oldprio < p->prio)
queue_flags |= ENQUEUE_HEAD;
enqueue_task(rq, p, queue_flags);
}
check_class_changed(rq, p, prev_class, oldprio);
preempt_disable(); /* avoid rq from going away on us */
task_rq_unlock(rq, p, &flags);
if (pi)
rt_mutex_adjust_pi(p);
/*
* Run balance callbacks after we've adjusted the PI chain.
*/
balance_callback(rq);
preempt_enable();
return 0;
}
static int _sched_setscheduler(struct task_struct *p, int policy,
const struct sched_param *param, bool check)
{
struct sched_attr attr = {
.sched_policy = policy,
.sched_priority = param->sched_priority,
.sched_nice = PRIO_TO_NICE(p->static_prio),
};
/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
policy &= ~SCHED_RESET_ON_FORK;
attr.sched_policy = policy;
}
return __sched_setscheduler(p, &attr, check, true);}
/**
* sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
* @p: the task in question.
* @policy: new policy.
* @param: structure containing the new RT priority.
*
* Return: 0 on success. An error code otherwise.
*
* NOTE that the task may be already dead.
*/
int sched_setscheduler(struct task_struct *p, int policy,
const struct sched_param *param)
{
return _sched_setscheduler(p, policy, param, true);
}
EXPORT_SYMBOL_GPL(sched_setscheduler);
int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
{
return __sched_setscheduler(p, attr, true, true);
}
EXPORT_SYMBOL_GPL(sched_setattr);
/**
* sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
* @p: the task in question.
* @policy: new policy.
* @param: structure containing the new RT priority.
*
* Just like sched_setscheduler, only don't bother checking if the
* current context has permission. For example, this is needed in
* stop_machine(): we create temporary high priority worker threads,
* but our caller might not have that capability.
*
* Return: 0 on success. An error code otherwise.
*/
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
const struct sched_param *param)
{
return _sched_setscheduler(p, policy, param, false);
}
EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
static int
do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
{
struct sched_param lparam;
struct task_struct *p;
int retval;
if (!param || pid < 0)
return -EINVAL;
if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
return -EFAULT;
rcu_read_lock();
retval = -ESRCH;
p = find_process_by_pid(pid);
if (p != NULL)
retval = sched_setscheduler(p, policy, &lparam);
rcu_read_unlock();
return retval;
}
/*
* Mimics kernel/events/core.c perf_copy_attr().
*/
static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
{
u32 size;
int ret;
if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
return -EFAULT;
/*
* zero the full structure, so that a short copy will be nice.
*/
memset(attr, 0, sizeof(*attr));
ret = get_user(size, &uattr->size);
if (ret)
return ret;
if (size > PAGE_SIZE) /* silly large */
goto err_size;
if (!size) /* abi compat */
size = SCHED_ATTR_SIZE_VER0;
if (size < SCHED_ATTR_SIZE_VER0)
goto err_size;
/*
* If we're handed a bigger struct than we know of,
* ensure all the unknown bits are 0 - i.e. new
* user-space does not rely on any kernel feature
* extensions we dont know about yet.
*/
if (size > sizeof(*attr)) {
unsigned char __user *addr;
unsigned char __user *end;
unsigned char val;
addr = (void __user *)uattr + sizeof(*attr);
end = (void __user *)uattr + size;
for (; addr < end; addr++) {
ret = get_user(val, addr);
if (ret)
return ret;
if (val)
goto err_size;
}
size = sizeof(*attr);
}
ret = copy_from_user(attr, uattr, size);
if (ret)
return -EFAULT;
/*
* XXX: do we want to be lenient like existing syscalls; or do we want
* to be strict and return an error on out-of-bounds values?
*/
attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
return 0;
err_size:
put_user(sizeof(*attr), &uattr->size);
return -E2BIG;
}
/**
* sys_sched_setscheduler - set/change the scheduler policy and RT priority
* @pid: the pid in question. * @policy: new policy.
* @param: structure containing the new RT priority.
*
* Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
struct sched_param __user *, param)
{
/* negative values for policy are not valid */
if (policy < 0)
return -EINVAL;
return do_sched_setscheduler(pid, policy, param);
}
/**
* sys_sched_setparam - set/change the RT priority of a thread
* @pid: the pid in question.
* @param: structure containing the new RT priority.
*
* Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
{
return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
}
/**
* sys_sched_setattr - same as above, but with extended sched_attr
* @pid: the pid in question.
* @uattr: structure containing the extended parameters.
* @flags: for future extension.
*/
SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
unsigned int, flags)
{
struct sched_attr attr;
struct task_struct *p;
int retval;
if (!uattr || pid < 0 || flags)
return -EINVAL;
retval = sched_copy_attr(uattr, &attr);
if (retval)
return retval;
if ((int)attr.sched_policy < 0)
return -EINVAL;
rcu_read_lock();
retval = -ESRCH;
p = find_process_by_pid(pid);
if (p != NULL)
retval = sched_setattr(p, &attr);
rcu_read_unlock();
return retval;
}
/**
* sys_sched_getscheduler - get the policy (scheduling class) of a thread
* @pid: the pid in question.
*
* Return: On success, the policy of the thread. Otherwise, a negative error
* code.
*/
SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
{
struct task_struct *p; int retval;
if (pid < 0)
return -EINVAL;
retval = -ESRCH;
rcu_read_lock();
p = find_process_by_pid(pid);
if (p) {
retval = security_task_getscheduler(p);
if (!retval)
retval = p->policy
| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
}
rcu_read_unlock();
return retval;
}
/**
* sys_sched_getparam - get the RT priority of a thread
* @pid: the pid in question.
* @param: structure containing the RT priority.
*
* Return: On success, 0 and the RT priority is in @param. Otherwise, an error
* code.
*/
SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
{
struct sched_param lp = { .sched_priority = 0 };
struct task_struct *p;
int retval;
if (!param || pid < 0)
return -EINVAL;
rcu_read_lock();
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
if (task_has_rt_policy(p))
lp.sched_priority = p->rt_priority;
rcu_read_unlock();
/*
* This one might sleep, we cannot do it with a spinlock held ...
*/
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
return retval;
out_unlock:
rcu_read_unlock();
return retval;
}
static int sched_read_attr(struct sched_attr __user *uattr,
struct sched_attr *attr,
unsigned int usize)
{
int ret;
if (!access_ok(VERIFY_WRITE, uattr, usize))
return -EFAULT;
/*
* If we're handed a smaller struct than we know of,
* ensure all the unknown bits are 0 - i.e. old
* user-space does not get uncomplete information.
*/
if (usize < sizeof(*attr)) {
unsigned char *addr;
unsigned char *end;
addr = (void *)attr + usize;
end = (void *)attr + sizeof(*attr);
for (; addr < end; addr++) {
if (*addr)
return -EFBIG;
}
attr->size = usize;
}
ret = copy_to_user(uattr, attr, attr->size);
if (ret)
return -EFAULT;
return 0;
}
/**
* sys_sched_getattr - similar to sched_getparam, but with sched_attr
* @pid: the pid in question.
* @uattr: structure containing the extended parameters.
* @size: sizeof(attr) for fwd/bwd comp.
* @flags: for future extension.
*/
SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
unsigned int, size, unsigned int, flags)
{
struct sched_attr attr = {
.size = sizeof(struct sched_attr),
};
struct task_struct *p;
int retval;
if (!uattr || pid < 0 || size > PAGE_SIZE ||
size < SCHED_ATTR_SIZE_VER0 || flags)
return -EINVAL;
rcu_read_lock();
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
attr.sched_policy = p->policy;
if (p->sched_reset_on_fork)
attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
if (task_has_dl_policy(p))
__getparam_dl(p, &attr);
else if (task_has_rt_policy(p))
attr.sched_priority = p->rt_priority;
else
attr.sched_nice = task_nice(p);
rcu_read_unlock();
retval = sched_read_attr(uattr, &attr, size); return retval;
out_unlock:
rcu_read_unlock();
return retval;
}
long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
{
cpumask_var_t cpus_allowed, new_mask;
struct task_struct *p;
int retval;
rcu_read_lock();
p = find_process_by_pid(pid);
if (!p) {
rcu_read_unlock();
return -ESRCH;
}
/* Prevent p going away */
get_task_struct(p);
rcu_read_unlock();
if (p->flags & PF_NO_SETAFFINITY) {
retval = -EINVAL;
goto out_put_task;
}
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_put_task;
}
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_free_cpus_allowed;
}
retval = -EPERM;
if (!check_same_owner(p)) {
rcu_read_lock();
if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
rcu_read_unlock();
goto out_free_new_mask;
}
rcu_read_unlock();
}
retval = security_task_setscheduler(p);
if (retval)
goto out_free_new_mask;
cpuset_cpus_allowed(p, cpus_allowed);
cpumask_and(new_mask, in_mask, cpus_allowed);
/*
* Since bandwidth control happens on root_domain basis,
* if admission test is enabled, we only admit -deadline
* tasks allowed to run on all the CPUs in the task's
* root_domain.
*/
#ifdef CONFIG_SMP
if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
rcu_read_lock();
if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
retval = -EBUSY;
rcu_read_unlock();
goto out_free_new_mask;
}
rcu_read_unlock(); }
#endif
again:
retval = __set_cpus_allowed_ptr(p, new_mask, true);
if (!retval) {
cpuset_cpus_allowed(p, cpus_allowed);
if (!cpumask_subset(new_mask, cpus_allowed)) {
/*
* We must have raced with a concurrent cpuset
* update. Just reset the cpus_allowed to the
* cpuset's cpus_allowed
*/
cpumask_copy(new_mask, cpus_allowed);
goto again;
}
}
out_free_new_mask:
free_cpumask_var(new_mask);
out_free_cpus_allowed:
free_cpumask_var(cpus_allowed);
out_put_task:
put_task_struct(p);
return retval;
}
static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
struct cpumask *new_mask)
{
if (len < cpumask_size())
cpumask_clear(new_mask);
else if (len > cpumask_size())
len = cpumask_size();
return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
}
/**
* sys_sched_setaffinity - set the cpu affinity of a process
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
* @user_mask_ptr: user-space pointer to the new cpu mask
*
* Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
unsigned long __user *, user_mask_ptr)
{
cpumask_var_t new_mask;
int retval;
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
return -ENOMEM;
retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
if (retval == 0)
retval = sched_setaffinity(pid, new_mask);
free_cpumask_var(new_mask);
return retval;
}
long sched_getaffinity(pid_t pid, struct cpumask *mask)
{
struct task_struct *p;
unsigned long flags;
int retval;
rcu_read_lock();
retval = -ESRCH; p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
raw_spin_lock_irqsave(&p->pi_lock, flags);
cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
out_unlock:
rcu_read_unlock();
return retval;
}
/**
* sys_sched_getaffinity - get the cpu affinity of a process
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
* @user_mask_ptr: user-space pointer to hold the current cpu mask
*
* Return: 0 on success. An error code otherwise.
*/
SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
unsigned long __user *, user_mask_ptr)
{
int ret;
cpumask_var_t mask;
if ((len * BITS_PER_BYTE) < nr_cpu_ids)
return -EINVAL;
if (len & (sizeof(unsigned long)-1))
return -EINVAL;
if (!alloc_cpumask_var(&mask, GFP_KERNEL))
return -ENOMEM;
ret = sched_getaffinity(pid, mask);
if (ret == 0) {
size_t retlen = min_t(size_t, len, cpumask_size());
if (copy_to_user(user_mask_ptr, mask, retlen))
ret = -EFAULT;
else
ret = retlen;
}
free_cpumask_var(mask);
return ret;
}
/**
* sys_sched_yield - yield the current processor to other threads.
*
* This function yields the current CPU to other tasks. If there are no
* other threads running on this CPU then this function will return.
*
* Return: 0.
*/
SYSCALL_DEFINE0(sched_yield)
{
struct rq *rq = this_rq_lock();
schedstat_inc(rq, yld_count);
current->sched_class->yield_task(rq);
/* * Since we are going to call schedule() anyway, there's
* no need to preempt or enable interrupts:
*/
__release(rq->lock);
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
do_raw_spin_unlock(&rq->lock);
sched_preempt_enable_no_resched();
schedule();
return 0;
}
int __sched _cond_resched(void)
{
if (should_resched(0)) {
preempt_schedule_common();
return 1;
}
return 0;
}
EXPORT_SYMBOL(_cond_resched);
/*
* __cond_resched_lock() - if a reschedule is pending, drop the given lock,
* call schedule, and on return reacquire the lock.
*
* This works OK both with and without CONFIG_PREEMPT. We do strange low-level
* operations here to prevent schedule() from being called twice (once via
* spin_unlock(), once by hand).
*/
int __cond_resched_lock(spinlock_t *lock)
{
int resched = should_resched(PREEMPT_LOCK_OFFSET);
int ret = 0;
lockdep_assert_held(lock);
if (spin_needbreak(lock) || resched) {
spin_unlock(lock);
if (resched)
preempt_schedule_common();
else
cpu_relax();
ret = 1;
spin_lock(lock);
}
return ret;
}
EXPORT_SYMBOL(__cond_resched_lock);
int __sched __cond_resched_softirq(void)
{
BUG_ON(!in_softirq());
if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
local_bh_enable();
preempt_schedule_common();
local_bh_disable();
return 1;
}
return 0;
}
EXPORT_SYMBOL(__cond_resched_softirq);
/**
* yield - yield the current processor to other threads.
*
* Do not ever use this function, there's a 99% chance you're doing it wrong.
* * The scheduler is at all times free to pick the calling task as the most
* eligible task to run, if removing the yield() call from your code breaks
* it, its already broken.
*
* Typical broken usage is:
*
* while (!event)
* yield();
*
* where one assumes that yield() will let 'the other' process run that will
* make event true. If the current task is a SCHED_FIFO task that will never
* happen. Never use yield() as a progress guarantee!!
*
* If you want to use yield() to wait for something, use wait_event().
* If you want to use yield() to be 'nice' for others, use cond_resched().
* If you still want to use yield(), do not!
*/
void __sched yield(void)
{
set_current_state(TASK_RUNNING);
sys_sched_yield();
}
EXPORT_SYMBOL(yield);
/**
* yield_to - yield the current processor to another thread in
* your thread group, or accelerate that thread toward the
* processor it's on.
* @p: target task
* @preempt: whether task preemption is allowed or not
*
* It's the caller's job to ensure that the target task struct
* can't go away on us before we can do any checks.
*
* Return:
* true (>0) if we indeed boosted the target task.
* false (0) if we failed to boost the target.
* -ESRCH if there's no task to yield to.
*/
int __sched yield_to(struct task_struct *p, bool preempt)
{
struct task_struct *curr = current;
struct rq *rq, *p_rq;
unsigned long flags;
int yielded = 0;
local_irq_save(flags);
rq = this_rq();
again:
p_rq = task_rq(p);
/*
* If we're the only runnable task on the rq and target rq also
* has only one task, there's absolutely no point in yielding.
*/
if (rq->nr_running == 1 && p_rq->nr_running == 1) {
yielded = -ESRCH;
goto out_irq;
}
double_rq_lock(rq, p_rq);
if (task_rq(p) != p_rq) {
double_rq_unlock(rq, p_rq);
goto again;
}
if (!curr->sched_class->yield_to_task)
goto out_unlock;
if (curr->sched_class != p->sched_class) goto out_unlock;
if (task_running(p_rq, p) || p->state)
goto out_unlock;
yielded = curr->sched_class->yield_to_task(rq, p, preempt);
if (yielded) {
schedstat_inc(rq, yld_count);
/*
* Make p's CPU reschedule; pick_next_entity takes care of
* fairness.
*/
if (preempt && rq != p_rq)
resched_curr(p_rq);
}
out_unlock:
double_rq_unlock(rq, p_rq);
out_irq:
local_irq_restore(flags);
if (yielded > 0)
schedule();
return yielded;
}
EXPORT_SYMBOL_GPL(yield_to);
/*
* This task is about to go to sleep on IO. Increment rq->nr_iowait so
* that process accounting knows that this is a task in IO wait state.
*/
long __sched io_schedule_timeout(long timeout)
{
int old_iowait = current->in_iowait;
struct rq *rq;
long ret;
current->in_iowait = 1;
blk_schedule_flush_plug(current);
delayacct_blkio_start();
rq = raw_rq();
atomic_inc(&rq->nr_iowait);
ret = schedule_timeout(timeout);
current->in_iowait = old_iowait;
atomic_dec(&rq->nr_iowait);
delayacct_blkio_end();
return ret;
}
EXPORT_SYMBOL(io_schedule_timeout);
/**
* sys_sched_get_priority_max - return maximum RT priority.
* @policy: scheduling class.
*
* Return: On success, this syscall returns the maximum
* rt_priority that can be used by a given scheduling class.
* On failure, a negative error code is returned.
*/
SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = MAX_USER_RT_PRIO-1;
break; case SCHED_DEADLINE:
case SCHED_NORMAL:
case SCHED_BATCH:
case SCHED_IDLE:
ret = 0;
break;
}
return ret;
}
/**
* sys_sched_get_priority_min - return minimum RT priority.
* @policy: scheduling class.
*
* Return: On success, this syscall returns the minimum
* rt_priority that can be used by a given scheduling class.
* On failure, a negative error code is returned.
*/
SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = 1;
break;
case SCHED_DEADLINE:
case SCHED_NORMAL:
case SCHED_BATCH:
case SCHED_IDLE:
ret = 0;
}
return ret;
}
/**
* sys_sched_rr_get_interval - return the default timeslice of a process.
* @pid: pid of the process.
* @interval: userspace pointer to the timeslice value.
*
* this syscall writes the default timeslice value of a given process
* into the user-space timespec buffer. A value of '0' means infinity.
*
* Return: On success, 0 and the timeslice is in @interval. Otherwise,
* an error code.
*/
SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
struct timespec __user *, interval)
{
struct task_struct *p;
unsigned int time_slice;
unsigned long flags;
struct rq *rq;
int retval;
struct timespec t;
if (pid < 0)
return -EINVAL;
retval = -ESRCH;
rcu_read_lock();
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
rq = task_rq_lock(p, &flags);
time_slice = 0;
if (p->sched_class->get_rr_interval)
time_slice = p->sched_class->get_rr_interval(rq, p);
task_rq_unlock(rq, p, &flags);
rcu_read_unlock();
jiffies_to_timespec(time_slice, &t);
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
return retval;
out_unlock:
rcu_read_unlock();
return retval;
}
static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
void sched_show_task(struct task_struct *p)
{
unsigned long free = 0;
int ppid;
unsigned long state = p->state;
if (state)
state = __ffs(state) + 1;
printk(KERN_INFO "%-15.15s %c", p->comm,
state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
#if BITS_PER_LONG == 32
if (state == TASK_RUNNING)
printk(KERN_CONT " running ");
else
printk(KERN_CONT " %08lx ", thread_saved_pc(p));
#else
if (state == TASK_RUNNING)
printk(KERN_CONT " running task ");
else
printk(KERN_CONT " %016lx ", thread_saved_pc(p));
#endif
#ifdef CONFIG_DEBUG_STACK_USAGE
free = stack_not_used(p);
#endif
ppid = 0;
rcu_read_lock();
if (pid_alive(p))
ppid = task_pid_nr(rcu_dereference(p->real_parent));
rcu_read_unlock();
printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
task_pid_nr(p), ppid,
(unsigned long)task_thread_info(p)->flags);
print_worker_info(KERN_INFO, p);
show_stack(p, NULL);
}
void show_state_filter(unsigned long state_filter)
{
struct task_struct *g, *p;
#if BITS_PER_LONG == 32
printk(KERN_INFO
" task PC stack pid father\n");
#else
printk(KERN_INFO
" task PC stack pid father\n");
#endif
rcu_read_lock();
for_each_process_thread(g, p) {
/*
* reset the NMI-timeout, listing all files on a slow * console might take a lot of time:
*/
touch_nmi_watchdog();
if (!state_filter || (p->state & state_filter))
sched_show_task(p);
}
touch_all_softlockup_watchdogs();
#ifdef CONFIG_SCHED_DEBUG
sysrq_sched_debug_show();
#endif
rcu_read_unlock();
/*
* Only show locks if all tasks are dumped:
*/
if (!state_filter)
debug_show_all_locks();
}
void init_idle_bootup_task(struct task_struct *idle)
{
idle->sched_class = &idle_sched_class;
}
/**
* init_idle - set up an idle thread for a given CPU
* @idle: task in question
* @cpu: cpu the idle task belongs to
*
* NOTE: this function does not set the idle thread's NEED_RESCHED
* flag, to make booting more robust.
*/
void init_idle(struct task_struct *idle, int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
raw_spin_lock_irqsave(&idle->pi_lock, flags);
raw_spin_lock(&rq->lock);
__sched_fork(0, idle);
idle->state = TASK_RUNNING;
idle->se.exec_start = sched_clock();
kasan_unpoison_task_stack(idle);
#ifdef CONFIG_SMP
/*
* Its possible that init_idle() gets called multiple times on a task,
* in that case do_set_cpus_allowed() will not do the right thing.
*
* And since this is boot we can forgo the serialization.
*/
set_cpus_allowed_common(idle, cpumask_of(cpu));
#endif
/*
* We're having a chicken and egg problem, even though we are
* holding rq->lock, the cpu isn't yet set to this cpu so the
* lockdep check in task_group() will fail.
*
* Similar case to sched_fork(). / Alternatively we could
* use task_rq_lock() here and obtain the other rq->lock.
*
* Silence PROVE_RCU
*/
rcu_read_lock();
__set_task_cpu(idle, cpu);
rcu_read_unlock();
rq->curr = rq->idle = idle;
idle->on_rq = TASK_ON_RQ_QUEUED;
#ifdef CONFIG_SMP
idle->on_cpu = 1;
#endif
raw_spin_unlock(&rq->lock);
raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
/* Set the preempt count _outside_ the spinlocks! */
init_idle_preempt_count(idle, cpu);
/*
* The idle tasks have their own, simple scheduling class:
*/
idle->sched_class = &idle_sched_class;
ftrace_graph_init_idle_task(idle, cpu);
vtime_init_idle(idle, cpu);
#ifdef CONFIG_SMP
sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
#endif
}
int 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;
if (!cpumask_weight(cur))
return ret;
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;
}
int task_can_attach(struct task_struct *p,
const struct cpumask *cs_cpus_allowed)
{
int ret = 0;
/*
* Kthreads which disallow setaffinity shouldn't be moved
* to a new cpuset; we don't want to change their cpu
* affinity and isolating such threads by their set of
* allowed nodes is unnecessary. Thus, cpusets are not
* applicable for such threads. This prevents checking for
* success of set_cpus_allowed_ptr() on all attached tasks
* before cpus_allowed may be changed.
*/
if (p->flags & PF_NO_SETAFFINITY) {
ret = -EINVAL;
goto out;
}
#ifdef CONFIG_SMP
if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
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;
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);
}
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
}
#endif
out:
return ret;
}
#ifdef CONFIG_SMP
#ifdef CONFIG_NUMA_BALANCING
/* Migrate current task p to target_cpu */
int migrate_task_to(struct task_struct *p, int target_cpu)
{
struct migration_arg arg = { p, target_cpu };
int curr_cpu = task_cpu(p);
if (curr_cpu == target_cpu)
return 0;
if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
return -EINVAL;
/* TODO: This is not properly updating schedstats */
trace_sched_move_numa(p, curr_cpu, target_cpu);
return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
}
/*
* Requeue a task on a given node and accurately track the number of NUMA
* tasks on the runqueues
*/
void sched_setnuma(struct task_struct *p, int nid)
{
struct rq *rq;
unsigned long flags;
bool queued, running;
rq = task_rq_lock(p, &flags);
queued = task_on_rq_queued(p);
running = task_current(rq, p);
if (queued)
dequeue_task(rq, p, DEQUEUE_SAVE);
if (running)
put_prev_task(rq, p);
p->numa_preferred_nid = nid;
if (running)
p->sched_class->set_curr_task(rq);
if (queued)
enqueue_task(rq, p, ENQUEUE_RESTORE);
task_rq_unlock(rq, p, &flags);
}
#endif /* CONFIG_NUMA_BALANCING */
#ifdef CONFIG_HOTPLUG_CPU
/*
* Ensures that the idle task is using init_mm right before its cpu goes
* offline.
*/
void idle_task_exit(void)
{
struct mm_struct *mm = current->active_mm;
BUG_ON(cpu_online(smp_processor_id()));
if (mm != &init_mm) {
switch_mm(mm, &init_mm, current);
finish_arch_post_lock_switch();
}
mmdrop(mm);
}
/*
* Since this CPU is going 'away' for a while, fold any nr_active delta
* we might have. Assumes we're called after migrate_tasks() so that the
* nr_active count is stable.
*
* Also see the comment "Global load-average calculations".
*/
static void calc_load_migrate(struct rq *rq)
{
long delta = calc_load_fold_active(rq);
if (delta)
atomic_long_add(delta, &calc_load_tasks);
}
static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
{
}
static const struct sched_class fake_sched_class = {
.put_prev_task = put_prev_task_fake,
};
static struct task_struct fake_task = {
/*
* Avoid pull_{rt,dl}_task()
*/
.prio = MAX_PRIO + 1,
.sched_class = &fake_sched_class,
};
/*
* Migrate all tasks from the rq, sleeping tasks will be migrated by
* try_to_wake_up()->select_task_rq().
*
* Called with rq->lock held even though we'er in stop_machine() and
* there's no concurrency possible, we hold the required locks anyway
* because of lock validation efforts.
*/
static void migrate_tasks(struct rq *dead_rq)
{
struct rq *rq = dead_rq;
struct task_struct *next, *stop = rq->stop; int dest_cpu;
/*
* Fudge the rq selection such that the below task selection loop
* doesn't get stuck on the currently eligible stop task.
*
* We're currently inside stop_machine() and the rq is either stuck
* in the stop_machine_cpu_stop() loop, or we're executing this code,
* either way we should never end up calling schedule() until we're
* done here.
*/
rq->stop = NULL;
/*
* put_prev_task() and pick_next_task() sched
* class method both need to have an up-to-date
* value of rq->clock[_task]
*/
update_rq_clock(rq);
for (;;) {
/*
* There's this thread running, bail when that's the only
* remaining thread.
*/
if (rq->nr_running == 1)
break;
/*
* pick_next_task assumes pinned rq->lock.
*/
lockdep_pin_lock(&rq->lock);
next = pick_next_task(rq, &fake_task);
BUG_ON(!next);
next->sched_class->put_prev_task(rq, next);
/*
* Rules for changing task_struct::cpus_allowed are holding
* both pi_lock and rq->lock, such that holding either
* stabilizes the mask.
*
* Drop rq->lock is not quite as disastrous as it usually is
* because !cpu_active at this point, which means load-balance
* will not interfere. Also, stop-machine.
*/
lockdep_unpin_lock(&rq->lock);
raw_spin_unlock(&rq->lock);
raw_spin_lock(&next->pi_lock);
raw_spin_lock(&rq->lock);
/*
* Since we're inside stop-machine, _nothing_ should have
* changed the task, WARN if weird stuff happened, because in
* that case the above rq->lock drop is a fail too.
*/
if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
raw_spin_unlock(&next->pi_lock);
continue;
}
/* Find suitable destination for @next, with force if needed. */
dest_cpu = select_fallback_rq(dead_rq->cpu, next);
rq = __migrate_task(rq, next, dest_cpu);
if (rq != dead_rq) {
raw_spin_unlock(&rq->lock);
rq = dead_rq;
raw_spin_lock(&rq->lock);
}
raw_spin_unlock(&next->pi_lock); }
rq->stop = stop;
}
#endif /* CONFIG_HOTPLUG_CPU */
static void set_rq_online(struct rq *rq)
{
if (!rq->online) {
const struct sched_class *class;
cpumask_set_cpu(rq->cpu, rq->rd->online);
rq->online = 1;
for_each_class(class) {
if (class->rq_online)
class->rq_online(rq);
}
}
}
static void set_rq_offline(struct rq *rq)
{
if (rq->online) {
const struct sched_class *class;
for_each_class(class) {
if (class->rq_offline)
class->rq_offline(rq);
}
cpumask_clear_cpu(rq->cpu, rq->rd->online);
rq->online = 0;
}
}
/*
* migration_call - callback that gets triggered when a CPU is added.
* Here we can start up the necessary migration thread for the new CPU.
*/
static int
migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int cpu = (long)hcpu;
unsigned long flags;
struct rq *rq = cpu_rq(cpu);
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
rq->calc_load_update = calc_load_update;
break;
case CPU_ONLINE:
/* Update our root-domain */
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_online(rq);
}
raw_spin_unlock_irqrestore(&rq->lock, flags);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
sched_ttwu_pending();
/* Update our root-domain */
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) { BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_offline(rq);
}
migrate_tasks(rq);
BUG_ON(rq->nr_running != 1); /* the migration thread */
raw_spin_unlock_irqrestore(&rq->lock, flags);
break;
case CPU_DEAD:
calc_load_migrate(rq);
break;
#endif
}
update_max_interval();
return NOTIFY_OK;
}
/*
* Register at high priority so that task migration (migrate_all_tasks)
* happens before everything else. This has to be lower priority than
* the notifier in the perf_event subsystem, though.
*/
static struct notifier_block migration_notifier = {
.notifier_call = migration_call,
.priority = CPU_PRI_MIGRATION,
};
static void set_cpu_rq_start_time(void)
{
int cpu = smp_processor_id();
struct rq *rq = cpu_rq(cpu);
rq->age_stamp = sched_clock_cpu(cpu);
}
static int sched_cpu_active(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
int cpu = (long)hcpu;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_STARTING:
set_cpu_rq_start_time();
return NOTIFY_OK;
case CPU_DOWN_FAILED:
set_cpu_active(cpu, true);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static int sched_cpu_inactive(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
set_cpu_active((long)hcpu, false);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static int __init migration_init(void)
{
void *cpu = (void *)(long)smp_processor_id(); int err;
/* Initialize migration for the boot CPU */
err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
BUG_ON(err == NOTIFY_BAD);
migration_call(&migration_notifier, CPU_ONLINE, cpu);
register_cpu_notifier(&migration_notifier);
/* Register cpu active notifiers */
cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
return 0;
}
early_initcall(migration_init);
static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
#ifdef CONFIG_SCHED_DEBUG
static __read_mostly int sched_debug_enabled;
static int __init sched_debug_setup(char *str)
{
sched_debug_enabled = 1;
return 0;
}
early_param("sched_debug", sched_debug_setup);
static inline bool sched_debug(void)
{
return sched_debug_enabled;
}
static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
struct cpumask *groupmask)
{
struct sched_group *group = sd->groups;
cpumask_clear(groupmask);
printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
if (!(sd->flags & SD_LOAD_BALANCE)) {
printk("does not load-balance\n");
if (sd->parent)
printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
" has parent");
return -1;
}
printk(KERN_CONT "span %*pbl level %s\n",
cpumask_pr_args(sched_domain_span(sd)), sd->name);
if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
printk(KERN_ERR "ERROR: domain->span does not contain "
"CPU%d\n", cpu);
}
if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
printk(KERN_ERR "ERROR: domain->groups does not contain"
" CPU%d\n", cpu);
}
printk(KERN_DEBUG "%*s groups:", level + 1, "");
do {
if (!group) {
printk("\n");
printk(KERN_ERR "ERROR: group is NULL\n");
break; }
if (!cpumask_weight(sched_group_cpus(group))) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: empty group\n");
break;
}
if (!(sd->flags & SD_OVERLAP) &&
cpumask_intersects(groupmask, sched_group_cpus(group))) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: repeated CPUs\n");
break;
}
cpumask_or(groupmask, groupmask, sched_group_cpus(group));
printk(KERN_CONT " %*pbl",
cpumask_pr_args(sched_group_cpus(group)));
if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
printk(KERN_CONT " (cpu_capacity = %d)",
group->sgc->capacity);
}
group = group->next;
} while (group != sd->groups);
printk(KERN_CONT "\n");
if (!cpumask_equal(sched_domain_span(sd), groupmask))
printk(KERN_ERR "ERROR: groups don't span domain->span\n");
if (sd->parent &&
!cpumask_subset(groupmask, sched_domain_span(sd->parent)))
printk(KERN_ERR "ERROR: parent span is not a superset "
"of domain->span\n");
return 0;
}
static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
int level = 0;
if (!sched_debug_enabled)
return;
if (!sd) {
printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
return;
}
printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
for (;;) {
if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
break;
level++;
sd = sd->parent;
if (!sd)
break;
}
}
#else /* !CONFIG_SCHED_DEBUG */
# define sched_domain_debug(sd, cpu) do { } while (0)
static inline bool sched_debug(void)
{
return false;
}
#endif /* CONFIG_SCHED_DEBUG */
static int sd_degenerate(struct sched_domain *sd){
if (cpumask_weight(sched_domain_span(sd)) == 1)
return 1;
/* Following flags need at least 2 groups */
if (sd->flags & (SD_LOAD_BALANCE |
SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
SD_SHARE_CPUCAPACITY |
SD_SHARE_PKG_RESOURCES |
SD_SHARE_POWERDOMAIN)) {
if (sd->groups != sd->groups->next)
return 0;
}
/* Following flags don't use groups */
if (sd->flags & (SD_WAKE_AFFINE))
return 0;
return 1;
}
static int
sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
{
unsigned long cflags = sd->flags, pflags = parent->flags;
if (sd_degenerate(parent))
return 1;
if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
return 0;
/* Flags needing groups don't count if only 1 group in parent */
if (parent->groups == parent->groups->next) {
pflags &= ~(SD_LOAD_BALANCE |
SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
SD_SHARE_CPUCAPACITY |
SD_SHARE_PKG_RESOURCES |
SD_PREFER_SIBLING |
SD_SHARE_POWERDOMAIN);
if (nr_node_ids == 1)
pflags &= ~SD_SERIALIZE;
}
if (~cflags & pflags)
return 0;
return 1;
}
static void free_rootdomain(struct rcu_head *rcu)
{
struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
cpupri_cleanup(&rd->cpupri);
cpudl_cleanup(&rd->cpudl);
free_cpumask_var(rd->dlo_mask);
free_cpumask_var(rd->rto_mask);
free_cpumask_var(rd->online);
free_cpumask_var(rd->span);
kfree(rd);
}
static void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
struct root_domain *old_rd = NULL;
unsigned long flags;
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
old_rd = rq->rd;
if (cpumask_test_cpu(rq->cpu, old_rd->online))
set_rq_offline(rq);
cpumask_clear_cpu(rq->cpu, old_rd->span);
/*
* If we dont want to free the old_rd yet then
* set old_rd to NULL to skip the freeing later
* in this function:
*/
if (!atomic_dec_and_test(&old_rd->refcount))
old_rd = NULL;
}
atomic_inc(&rd->refcount);
rq->rd = rd;
cpumask_set_cpu(rq->cpu, rd->span);
if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
set_rq_online(rq);
raw_spin_unlock_irqrestore(&rq->lock, flags);
if (old_rd)
call_rcu_sched(&old_rd->rcu, free_rootdomain);
}
static int init_rootdomain(struct root_domain *rd)
{
memset(rd, 0, sizeof(*rd));
if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
goto out;
if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
goto free_span;
if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
goto free_online;
if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
goto free_dlo_mask;
init_dl_bw(&rd->dl_bw);
if (cpudl_init(&rd->cpudl) != 0)
goto free_dlo_mask;
if (cpupri_init(&rd->cpupri) != 0)
goto free_rto_mask;
return 0;
free_rto_mask:
free_cpumask_var(rd->rto_mask);
free_dlo_mask:
free_cpumask_var(rd->dlo_mask);
free_online:
free_cpumask_var(rd->online);
free_span:
free_cpumask_var(rd->span);
out:
return -ENOMEM;
}
/*
* By default the system creates a single root-domain with all cpus as
* members (mimicking the global state we have today).
*/struct root_domain def_root_domain;
static void init_defrootdomain(void)
{
init_rootdomain(&def_root_domain);
atomic_set(&def_root_domain.refcount, 1);
}
static struct root_domain *alloc_rootdomain(void)
{
struct root_domain *rd;
rd = kmalloc(sizeof(*rd), GFP_KERNEL);
if (!rd)
return NULL;
if (init_rootdomain(rd) != 0) {
kfree(rd);
return NULL;
}
return rd;
}
static void free_sched_groups(struct sched_group *sg, int free_sgc)
{
struct sched_group *tmp, *first;
if (!sg)
return;
first = sg;
do {
tmp = sg->next;
if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
kfree(sg->sgc);
kfree(sg);
sg = tmp;
} while (sg != first);
}
static void free_sched_domain(struct rcu_head *rcu)
{
struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
/*
* If its an overlapping domain it has private groups, iterate and
* nuke them all.
*/
if (sd->flags & SD_OVERLAP) {
free_sched_groups(sd->groups, 1);
} else if (atomic_dec_and_test(&sd->groups->ref)) {
kfree(sd->groups->sgc);
kfree(sd->groups);
}
kfree(sd);
}
static void destroy_sched_domain(struct sched_domain *sd, int cpu)
{
call_rcu(&sd->rcu, free_sched_domain);
}
static void destroy_sched_domains(struct sched_domain *sd, int cpu)
{
for (; sd; sd = sd->parent)
destroy_sched_domain(sd, cpu);}
/*
* Keep a special pointer to the highest sched_domain that has
* SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
* allows us to avoid some pointer chasing select_idle_sibling().
*
* Also keep a unique ID per domain (we use the first cpu number in
* the cpumask of the domain), this allows us to quickly tell if
* two cpus are in the same cache domain, see cpus_share_cache().
*/
DEFINE_PER_CPU(struct sched_domain *, sd_llc);
DEFINE_PER_CPU(int, sd_llc_size);
DEFINE_PER_CPU(int, sd_llc_id);
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
DEFINE_PER_CPU(struct sched_domain *, sd_busy);
DEFINE_PER_CPU(struct sched_domain *, sd_asym);
static void update_top_cache_domain(int cpu)
{
struct sched_domain *sd;
struct sched_domain *busy_sd = NULL;
int id = cpu;
int size = 1;
sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
if (sd) {
id = cpumask_first(sched_domain_span(sd));
size = cpumask_weight(sched_domain_span(sd));
busy_sd = sd->parent; /* sd_busy */
}
rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
per_cpu(sd_llc_size, cpu) = size;
per_cpu(sd_llc_id, cpu) = id;
sd = lowest_flag_domain(cpu, SD_NUMA);
rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
}
/*
* Attach the domain 'sd' to 'cpu' as its base domain. Callers must
* hold the hotplug lock.
*/
static void
cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct sched_domain *tmp;
/* Remove the sched domains which do not contribute to scheduling. */
for (tmp = sd; tmp; ) {
struct sched_domain *parent = tmp->parent;
if (!parent)
break;
if (sd_parent_degenerate(tmp, parent)) {
tmp->parent = parent->parent;
if (parent->parent)
parent->parent->child = tmp;
/*
* Transfer SD_PREFER_SIBLING down in case of a
* degenerate parent; the spans match for this
* so the property transfers.
*/
if (parent->flags & SD_PREFER_SIBLING) tmp->flags |= SD_PREFER_SIBLING;
destroy_sched_domain(parent, cpu);
} else
tmp = tmp->parent;
}
if (sd && sd_degenerate(sd)) {
tmp = sd;
sd = sd->parent;
destroy_sched_domain(tmp, cpu);
if (sd)
sd->child = NULL;
}
sched_domain_debug(sd, cpu);
rq_attach_root(rq, rd);
tmp = rq->sd;
rcu_assign_pointer(rq->sd, sd);
destroy_sched_domains(tmp, cpu);
update_top_cache_domain(cpu);
}
/* Setup the mask of cpus configured for isolated domains */
static int __init isolated_cpu_setup(char *str)
{
int ret;
alloc_bootmem_cpumask_var(&cpu_isolated_map);
ret = cpulist_parse(str, cpu_isolated_map);
if (ret) {
pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
return 0;
}
return 1;
}
__setup("isolcpus=", isolated_cpu_setup);
struct s_data {
struct sched_domain ** __percpu sd;
struct root_domain *rd;
};
enum s_alloc {
sa_rootdomain,
sa_sd,
sa_sd_storage,
sa_none,
};
/*
* Build an iteration mask that can exclude certain CPUs from the upwards
* domain traversal.
*
* Asymmetric node setups can result in situations where the domain tree is of
* unequal depth, make sure to skip domains that already cover the entire
* range.
*
* In that case build_sched_domains() will have terminated the iteration early
* and our sibling sd spans will be empty. Domains should always include the
* cpu they're built on, so check that.
*
*/
static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
{
const struct cpumask *span = sched_domain_span(sd);
struct sd_data *sdd = sd->private;
struct sched_domain *sibling;
int i;
for_each_cpu(i, span) {
sibling = *per_cpu_ptr(sdd->sd, i);
if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
continue;
cpumask_set_cpu(i, sched_group_mask(sg));
}
}
/*
* Return the canonical balance cpu for this group, this is the first cpu
* of this group that's also in the iteration mask.
*/
int group_balance_cpu(struct sched_group *sg)
{
return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
}
static int
build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
const struct cpumask *span = sched_domain_span(sd);
struct cpumask *covered = sched_domains_tmpmask;
struct sd_data *sdd = sd->private;
struct sched_domain *sibling;
int i;
cpumask_clear(covered);
for_each_cpu(i, span) {
struct cpumask *sg_span;
if (cpumask_test_cpu(i, covered))
continue;
sibling = *per_cpu_ptr(sdd->sd, i);
/* See the comment near build_group_mask(). */
if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
continue;
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(cpu));
if (!sg)
goto fail;
sg_span = sched_group_cpus(sg);
if (sibling->child)
cpumask_copy(sg_span, sched_domain_span(sibling->child));
else
cpumask_set_cpu(i, sg_span);
cpumask_or(covered, covered, sg_span);
sg->sgc = *per_cpu_ptr(sdd->sgc, i);
if (atomic_inc_return(&sg->sgc->ref) == 1)
build_group_mask(sd, sg);
/*
* Initialize sgc->capacity such that even if we mess up the
* domains and no possible iteration will get us here, we won't
* die on a /0 trap.
*/
sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
/*
* Make sure the first group of this domain contains the * canonical balance cpu. Otherwise the sched_domain iteration
* breaks. See update_sg_lb_stats().
*/
if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
group_balance_cpu(sg) == cpu)
groups = sg;
if (!first)
first = sg;
if (last)
last->next = sg;
last = sg;
last->next = first;
}
sd->groups = groups;
return 0;
fail:
free_sched_groups(first, 0);
return -ENOMEM;
}
static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
{
struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
struct sched_domain *child = sd->child;
if (child)
cpu = cpumask_first(sched_domain_span(child));
if (sg) {
*sg = *per_cpu_ptr(sdd->sg, cpu);
(*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
}
return cpu;
}
/*
* build_sched_groups will build a circular linked list of the groups
* covered by the given span, and will set each group's ->cpumask correctly,
* and ->cpu_capacity to 0.
*
* Assumes the sched_domain tree is fully constructed
*/
static int
build_sched_groups(struct sched_domain *sd, int cpu)
{
struct sched_group *first = NULL, *last = NULL;
struct sd_data *sdd = sd->private;
const struct cpumask *span = sched_domain_span(sd);
struct cpumask *covered;
int i;
get_group(cpu, sdd, &sd->groups);
atomic_inc(&sd->groups->ref);
if (cpu != cpumask_first(span))
return 0;
lockdep_assert_held(&sched_domains_mutex);
covered = sched_domains_tmpmask;
cpumask_clear(covered);
for_each_cpu(i, span) {
struct sched_group *sg; int group, j;
if (cpumask_test_cpu(i, covered))
continue;
group = get_group(i, sdd, &sg);
cpumask_setall(sched_group_mask(sg));
for_each_cpu(j, span) {
if (get_group(j, sdd, NULL) != group)
continue;
cpumask_set_cpu(j, covered);
cpumask_set_cpu(j, sched_group_cpus(sg));
}
if (!first)
first = sg;
if (last)
last->next = sg;
last = sg;
}
last->next = first;
return 0;
}
/*
* Initialize sched groups cpu_capacity.
*
* cpu_capacity indicates the capacity of sched group, which is used while
* distributing the load between different sched groups in a sched domain.
* Typically cpu_capacity for all the groups in a sched domain will be same
* unless there are asymmetries in the topology. If there are asymmetries,
* group having more cpu_capacity will pickup more load compared to the
* group having less cpu_capacity.
*/
static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
{
struct sched_group *sg = sd->groups;
WARN_ON(!sg);
do {
sg->group_weight = cpumask_weight(sched_group_cpus(sg));
sg = sg->next;
} while (sg != sd->groups);
if (cpu != group_balance_cpu(sg))
return;
update_group_capacity(sd, cpu);
atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
}
/*
* Initializers for schedule domains
* Non-inlined to reduce accumulated stack pressure in build_sched_domains()
*/
static int default_relax_domain_level = -1;
int sched_domain_level_max;
static int __init setup_relax_domain_level(char *str)
{
if (kstrtoint(str, 0, &default_relax_domain_level))
pr_warn("Unable to set relax_domain_level\n");
return 1;
}__setup("relax_domain_level=", setup_relax_domain_level);
static void set_domain_attribute(struct sched_domain *sd,
struct sched_domain_attr *attr)
{
int request;
if (!attr || attr->relax_domain_level < 0) {
if (default_relax_domain_level < 0)
return;
else
request = default_relax_domain_level;
} else
request = attr->relax_domain_level;
if (request < sd->level) {
/* turn off idle balance on this domain */
sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
} else {
/* turn on idle balance on this domain */
sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
}
}
static void __sdt_free(const struct cpumask *cpu_map);
static int __sdt_alloc(const struct cpumask *cpu_map);
static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
const struct cpumask *cpu_map)
{
switch (what) {
case sa_rootdomain:
if (!atomic_read(&d->rd->refcount))
free_rootdomain(&d->rd->rcu); /* fall through */
case sa_sd:
free_percpu(d->sd); /* fall through */
case sa_sd_storage:
__sdt_free(cpu_map); /* fall through */
case sa_none:
break;
}
}
static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
const struct cpumask *cpu_map)
{
memset(d, 0, sizeof(*d));
if (__sdt_alloc(cpu_map))
return sa_sd_storage;
d->sd = alloc_percpu(struct sched_domain *);
if (!d->sd)
return sa_sd_storage;
d->rd = alloc_rootdomain();
if (!d->rd)
return sa_sd;
return sa_rootdomain;
}
/*
* NULL the sd_data elements we've used to build the sched_domain and
* sched_group structure so that the subsequent __free_domain_allocs()
* will not free the data we're using.
*/
static void claim_allocations(int cpu, struct sched_domain *sd)
{
struct sd_data *sdd = sd->private;
WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
*per_cpu_ptr(sdd->sd, cpu) = NULL;
if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
*per_cpu_ptr(sdd->sg, cpu) = NULL;
if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
*per_cpu_ptr(sdd->sgc, cpu) = NULL;
}
#ifdef CONFIG_NUMA
static int sched_domains_numa_levels;
enum numa_topology_type sched_numa_topology_type;
static int *sched_domains_numa_distance;
int sched_max_numa_distance;
static struct cpumask ***sched_domains_numa_masks;
static int sched_domains_curr_level;
#endif
/*
* SD_flags allowed in topology descriptions.
*
* SD_SHARE_CPUCAPACITY - describes SMT topologies
* SD_SHARE_PKG_RESOURCES - describes shared caches
* SD_NUMA - describes NUMA topologies
* SD_SHARE_POWERDOMAIN - describes shared power domain
*
* Odd one out:
* SD_ASYM_PACKING - describes SMT quirks
*/
#define TOPOLOGY_SD_FLAGS \
(SD_SHARE_CPUCAPACITY | \
SD_SHARE_PKG_RESOURCES | \
SD_NUMA | \
SD_ASYM_PACKING | \
SD_SHARE_POWERDOMAIN)
static struct sched_domain *
sd_init(struct sched_domain_topology_level *tl, int cpu)
{
struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
int sd_weight, sd_flags = 0;
#ifdef CONFIG_NUMA
/*
* Ugly hack to pass state to sd_numa_mask()...
*/
sched_domains_curr_level = tl->numa_level;
#endif
sd_weight = cpumask_weight(tl->mask(cpu));
if (tl->sd_flags)
sd_flags = (*tl->sd_flags)();
if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
"wrong sd_flags in topology description\n"))
sd_flags &= ~TOPOLOGY_SD_FLAGS;
*sd = (struct sched_domain){
.min_interval = sd_weight,
.max_interval = 2*sd_weight,
.busy_factor = 32,
.imbalance_pct = 125,
.cache_nice_tries = 0,
.busy_idx = 0,
.idle_idx = 0,
.newidle_idx = 0,
.wake_idx = 0,
.forkexec_idx = 0,
.flags = 1*SD_LOAD_BALANCE
| 1*SD_BALANCE_NEWIDLE | 1*SD_BALANCE_EXEC
| 1*SD_BALANCE_FORK
| 0*SD_BALANCE_WAKE
| 1*SD_WAKE_AFFINE
| 0*SD_SHARE_CPUCAPACITY
| 0*SD_SHARE_PKG_RESOURCES
| 0*SD_SERIALIZE
| 0*SD_PREFER_SIBLING
| 0*SD_NUMA
| sd_flags
,
.last_balance = jiffies,
.balance_interval = sd_weight,
.smt_gain = 0,
.max_newidle_lb_cost = 0,
.next_decay_max_lb_cost = jiffies,
#ifdef CONFIG_SCHED_DEBUG
.name = tl->name,
#endif
};
/*
* Convert topological properties into behaviour.
*/
if (sd->flags & SD_SHARE_CPUCAPACITY) {
sd->flags |= SD_PREFER_SIBLING;
sd->imbalance_pct = 110;
sd->smt_gain = 1178; /* ~15% */
} else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
sd->imbalance_pct = 117;
sd->cache_nice_tries = 1;
sd->busy_idx = 2;
#ifdef CONFIG_NUMA
} else if (sd->flags & SD_NUMA) {
sd->cache_nice_tries = 2;
sd->busy_idx = 3;
sd->idle_idx = 2;
sd->flags |= SD_SERIALIZE;
if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
sd->flags &= ~(SD_BALANCE_EXEC |
SD_BALANCE_FORK |
SD_WAKE_AFFINE);
}
#endif
} else {
sd->flags |= SD_PREFER_SIBLING;
sd->cache_nice_tries = 1;
sd->busy_idx = 2;
sd->idle_idx = 1;
}
sd->private = &tl->data;
return sd;
}
/*
* Topology list, bottom-up.
*/
static struct sched_domain_topology_level default_topology[] = {
#ifdef CONFIG_SCHED_SMT
{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
#endif
#ifdef CONFIG_SCHED_MC { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
#endif
{ cpu_cpu_mask, SD_INIT_NAME(DIE) },
{ NULL, },
};
static struct sched_domain_topology_level *sched_domain_topology =
default_topology;
#define for_each_sd_topology(tl) \
for (tl = sched_domain_topology; tl->mask; tl++)
void set_sched_topology(struct sched_domain_topology_level *tl)
{
sched_domain_topology = tl;
}
#ifdef CONFIG_NUMA
static const struct cpumask *sd_numa_mask(int cpu)
{
return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
}
static void sched_numa_warn(const char *str)
{
static int done = false;
int i,j;
if (done)
return;
done = true;
printk(KERN_WARNING "ERROR: %s\n\n", str);
for (i = 0; i < nr_node_ids; i++) {
printk(KERN_WARNING " ");
for (j = 0; j < nr_node_ids; j++)
printk(KERN_CONT "%02d ", node_distance(i,j));
printk(KERN_CONT "\n");
}
printk(KERN_WARNING "\n");
}
bool find_numa_distance(int distance)
{
int i;
if (distance == node_distance(0, 0))
return true;
for (i = 0; i < sched_domains_numa_levels; i++) {
if (sched_domains_numa_distance[i] == distance)
return true;
}
return false;
}
/*
* A system can have three types of NUMA topology:
* NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
* NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
* NUMA_BACKPLANE: nodes can reach other nodes through a backplane
*
* The difference between a glueless mesh topology and a backplane
* topology lies in whether communication between not directly
* connected nodes goes through intermediary nodes (where programs
* could run), or through backplane controllers. This affects * placement of programs.
*
* The type of topology can be discerned with the following tests:
* - If the maximum distance between any nodes is 1 hop, the system
* is directly connected.
* - If for two nodes A and B, located N > 1 hops away from each other,
* there is an intermediary node C, which is < N hops away from both
* nodes A and B, the system is a glueless mesh.
*/
static void init_numa_topology_type(void)
{
int a, b, c, n;
n = sched_max_numa_distance;
if (sched_domains_numa_levels <= 1) {
sched_numa_topology_type = NUMA_DIRECT;
return;
}
for_each_online_node(a) {
for_each_online_node(b) {
/* Find two nodes furthest removed from each other. */
if (node_distance(a, b) < n)
continue;
/* Is there an intermediary node between a and b? */
for_each_online_node(c) {
if (node_distance(a, c) < n &&
node_distance(b, c) < n) {
sched_numa_topology_type =
NUMA_GLUELESS_MESH;
return;
}
}
sched_numa_topology_type = NUMA_BACKPLANE;
return;
}
}
}
static void sched_init_numa(void)
{
int next_distance, curr_distance = node_distance(0, 0);
struct sched_domain_topology_level *tl;
int level = 0;
int i, j, k;
sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
if (!sched_domains_numa_distance)
return;
/*
* O(nr_nodes^2) deduplicating selection sort -- in order to find the
* unique distances in the node_distance() table.
*
* Assumes node_distance(0,j) includes all distances in
* node_distance(i,j) in order to avoid cubic time.
*/
next_distance = curr_distance;
for (i = 0; i < nr_node_ids; i++) {
for (j = 0; j < nr_node_ids; j++) {
for (k = 0; k < nr_node_ids; k++) {
int distance = node_distance(i, k);
if (distance > curr_distance &&
(distance < next_distance ||
next_distance == curr_distance))
next_distance = distance;
/*
* While not a strong assumption it would be nice to know
* about cases where if node A is connected to B, B is not
* equally connected to A.
*/
if (sched_debug() && node_distance(k, i) != distance)
sched_numa_warn("Node-distance not symmetric");
if (sched_debug() && i && !find_numa_distance(distance))
sched_numa_warn("Node-0 not representative");
}
if (next_distance != curr_distance) {
sched_domains_numa_distance[level++] = next_distance;
sched_domains_numa_levels = level;
curr_distance = next_distance;
} else break;
}
/*
* In case of sched_debug() we verify the above assumption.
*/
if (!sched_debug())
break;
}
if (!level)
return;
/*
* 'level' contains the number of unique distances, excluding the
* identity distance node_distance(i,i).
*
* The sched_domains_numa_distance[] array includes the actual distance
* numbers.
*/
/*
* Here, we should temporarily reset sched_domains_numa_levels to 0.
* If it fails to allocate memory for array sched_domains_numa_masks[][],
* the array will contain less then 'level' members. This could be
* dangerous when we use it to iterate array sched_domains_numa_masks[][]
* in other functions.
*
* We reset it to 'level' at the end of this function.
*/
sched_domains_numa_levels = 0;
sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
if (!sched_domains_numa_masks)
return;
/*
* Now for each level, construct a mask per node which contains all
* cpus of nodes that are that many hops away from us.
*/
for (i = 0; i < level; i++) {
sched_domains_numa_masks[i] =
kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
if (!sched_domains_numa_masks[i])
return;
for (j = 0; j < nr_node_ids; j++) {
struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
if (!mask)
return;
sched_domains_numa_masks[i][j] = mask;
for_each_node(k) { if (node_distance(j, k) > sched_domains_numa_distance[i])
continue;
cpumask_or(mask, mask, cpumask_of_node(k));
}
}
}
/* Compute default topology size */
for (i = 0; sched_domain_topology[i].mask; i++);
tl = kzalloc((i + level + 1) *
sizeof(struct sched_domain_topology_level), GFP_KERNEL);
if (!tl)
return;
/*
* Copy the default topology bits..
*/
for (i = 0; sched_domain_topology[i].mask; i++)
tl[i] = sched_domain_topology[i];
/*
* .. and append 'j' levels of NUMA goodness.
*/
for (j = 0; j < level; i++, j++) {
tl[i] = (struct sched_domain_topology_level){
.mask = sd_numa_mask,
.sd_flags = cpu_numa_flags,
.flags = SDTL_OVERLAP,
.numa_level = j,
SD_INIT_NAME(NUMA)
};
}
sched_domain_topology = tl;
sched_domains_numa_levels = level;
sched_max_numa_distance = sched_domains_numa_distance[level - 1];
init_numa_topology_type();
}
static void sched_domains_numa_masks_set(int cpu)
{
int i, j;
int node = cpu_to_node(cpu);
for (i = 0; i < sched_domains_numa_levels; i++) {
for (j = 0; j < nr_node_ids; j++) {
if (node_distance(j, node) <= sched_domains_numa_distance[i])
cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
}
}
}
static void sched_domains_numa_masks_clear(int cpu)
{
int i, j;
for (i = 0; i < sched_domains_numa_levels; i++) {
for (j = 0; j < nr_node_ids; j++)
cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
}
}
/*
* Update sched_domains_numa_masks[level][node] array when new cpus
* are onlined.
*/
static int sched_domains_numa_masks_update(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
int cpu = (long)hcpu;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
sched_domains_numa_masks_set(cpu);
break;
case CPU_DEAD:
sched_domains_numa_masks_clear(cpu);
break;
default:
return NOTIFY_DONE;
}
return NOTIFY_OK;
}
#else
static inline void sched_init_numa(void)
{
}
static int sched_domains_numa_masks_update(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
return 0;
}
#endif /* CONFIG_NUMA */
static int __sdt_alloc(const struct cpumask *cpu_map)
{
struct sched_domain_topology_level *tl;
int j;
for_each_sd_topology(tl) {
struct sd_data *sdd = &tl->data;
sdd->sd = alloc_percpu(struct sched_domain *);
if (!sdd->sd)
return -ENOMEM;
sdd->sg = alloc_percpu(struct sched_group *);
if (!sdd->sg)
return -ENOMEM;
sdd->sgc = alloc_percpu(struct sched_group_capacity *);
if (!sdd->sgc)
return -ENOMEM;
for_each_cpu(j, cpu_map) {
struct sched_domain *sd;
struct sched_group *sg;
struct sched_group_capacity *sgc;
sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sd)
return -ENOMEM;
*per_cpu_ptr(sdd->sd, j) = sd;
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sg)
return -ENOMEM;
sg->next = sg;
*per_cpu_ptr(sdd->sg, j) = sg;
sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sgc)
return -ENOMEM;
*per_cpu_ptr(sdd->sgc, j) = sgc;
}
}
return 0;
}
static void __sdt_free(const struct cpumask *cpu_map)
{
struct sched_domain_topology_level *tl;
int j;
for_each_sd_topology(tl) {
struct sd_data *sdd = &tl->data;
for_each_cpu(j, cpu_map) {
struct sched_domain *sd;
if (sdd->sd) {
sd = *per_cpu_ptr(sdd->sd, j);
if (sd && (sd->flags & SD_OVERLAP))
free_sched_groups(sd->groups, 0);
kfree(*per_cpu_ptr(sdd->sd, j));
}
if (sdd->sg)
kfree(*per_cpu_ptr(sdd->sg, j));
if (sdd->sgc)
kfree(*per_cpu_ptr(sdd->sgc, j));
}
free_percpu(sdd->sd);
sdd->sd = NULL;
free_percpu(sdd->sg);
sdd->sg = NULL;
free_percpu(sdd->sgc);
sdd->sgc = NULL;
}
}
struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
const struct cpumask *cpu_map, struct sched_domain_attr *attr,
struct sched_domain *child, int cpu)
{
struct sched_domain *sd = sd_init(tl, cpu);
if (!sd)
return child;
cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
if (child) {
sd->level = child->level + 1;
sched_domain_level_max = max(sched_domain_level_max, sd->level);
child->parent = sd;
sd->child = child;
if (!cpumask_subset(sched_domain_span(child),
sched_domain_span(sd))) {
pr_err("BUG: arch topology borken\n");
#ifdef CONFIG_SCHED_DEBUG
pr_err(" the %s domain not a subset of the %s domain\n",
child->name, sd->name);
#endif /* Fixup, ensure @sd has at least @child cpus. */
cpumask_or(sched_domain_span(sd),
sched_domain_span(sd),
sched_domain_span(child));
}
}
set_domain_attribute(sd, attr);
return sd;
}
/*
* Build sched domains for a given set of cpus and attach the sched domains
* to the individual cpus
*/
static int build_sched_domains(const struct cpumask *cpu_map,
struct sched_domain_attr *attr)
{
enum s_alloc alloc_state;
struct sched_domain *sd;
struct s_data d;
int i, ret = -ENOMEM;
alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
if (alloc_state != sa_rootdomain)
goto error;
/* Set up domains for cpus specified by the cpu_map. */
for_each_cpu(i, cpu_map) {
struct sched_domain_topology_level *tl;
sd = NULL;
for_each_sd_topology(tl) {
sd = build_sched_domain(tl, cpu_map, attr, sd, i);
if (tl == sched_domain_topology)
*per_cpu_ptr(d.sd, i) = sd;
if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
sd->flags |= SD_OVERLAP;
if (cpumask_equal(cpu_map, sched_domain_span(sd)))
break;
}
}
/* Build the groups for the domains */
for_each_cpu(i, cpu_map) {
for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
sd->span_weight = cpumask_weight(sched_domain_span(sd));
if (sd->flags & SD_OVERLAP) {
if (build_overlap_sched_groups(sd, i))
goto error;
} else {
if (build_sched_groups(sd, i))
goto error;
}
}
}
/* Calculate CPU capacity for physical packages and nodes */
for (i = nr_cpumask_bits-1; i >= 0; i--) {
if (!cpumask_test_cpu(i, cpu_map))
continue;
for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
claim_allocations(i, sd);
init_sched_groups_capacity(i, sd);
}
}
/* Attach the domains */ rcu_read_lock();
for_each_cpu(i, cpu_map) {
sd = *per_cpu_ptr(d.sd, i);
cpu_attach_domain(sd, d.rd, i);
}
rcu_read_unlock();
ret = 0;
error:
__free_domain_allocs(&d, alloc_state, cpu_map);
return ret;
}
static cpumask_var_t *doms_cur; /* current sched domains */
static int ndoms_cur; /* number of sched domains in 'doms_cur' */
static struct sched_domain_attr *dattr_cur;
/* attribues of custom domains in 'doms_cur' */
/*
* Special case: If a kmalloc of a doms_cur partition (array of
* cpumask) fails, then fallback to a single sched domain,
* as determined by the single cpumask fallback_doms.
*/
static cpumask_var_t fallback_doms;
/*
* arch_update_cpu_topology lets virtualized architectures update the
* cpu core maps. It is supposed to return 1 if the topology changed
* or 0 if it stayed the same.
*/
int __weak arch_update_cpu_topology(void)
{
return 0;
}
cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
{
int i;
cpumask_var_t *doms;
doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
if (!doms)
return NULL;
for (i = 0; i < ndoms; i++) {
if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
free_sched_domains(doms, i);
return NULL;
}
}
return doms;
}
void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
{
unsigned int i;
for (i = 0; i < ndoms; i++)
free_cpumask_var(doms[i]);
kfree(doms);
}
/*
* Set up scheduler domains and groups. Callers must hold the hotplug lock.
* For now this just excludes isolated cpus, but could be used to
* exclude other special cases in the future.
*/
static int init_sched_domains(const struct cpumask *cpu_map)
{
int err;
arch_update_cpu_topology(); ndoms_cur = 1;
doms_cur = alloc_sched_domains(ndoms_cur);
if (!doms_cur)
doms_cur = &fallback_doms;
cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
err = build_sched_domains(doms_cur[0], NULL);
register_sched_domain_sysctl();
return err;
}
/*
* Detach sched domains from a group of cpus specified in cpu_map
* These cpus will now be attached to the NULL domain
*/
static void detach_destroy_domains(const struct cpumask *cpu_map)
{
int i;
rcu_read_lock();
for_each_cpu(i, cpu_map)
cpu_attach_domain(NULL, &def_root_domain, i);
rcu_read_unlock();
}
/* handle null as "default" */
static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
struct sched_domain_attr *new, int idx_new)
{
struct sched_domain_attr tmp;
/* fast path */
if (!new && !cur)
return 1;
tmp = SD_ATTR_INIT;
return !memcmp(cur ? (cur + idx_cur) : &tmp,
new ? (new + idx_new) : &tmp,
sizeof(struct sched_domain_attr));
}
/*
* Partition sched domains as specified by the 'ndoms_new'
* cpumasks in the array doms_new[] of cpumasks. This compares
* doms_new[] to the current sched domain partitioning, doms_cur[].
* It destroys each deleted domain and builds each new domain.
*
* 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
* The masks don't intersect (don't overlap.) We should setup one
* sched domain for each mask. CPUs not in any of the cpumasks will
* not be load balanced. If the same cpumask appears both in the
* current 'doms_cur' domains and in the new 'doms_new', we can leave
* it as it is.
*
* The passed in 'doms_new' should be allocated using
* alloc_sched_domains. This routine takes ownership of it and will
* free_sched_domains it when done with it. If the caller failed the
* alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
* and partition_sched_domains() will fallback to the single partition
* 'fallback_doms', it also forces the domains to be rebuilt.
*
* If doms_new == NULL it will be replaced with cpu_online_mask.
* ndoms_new == 0 is a special case for destroying existing domains,
* and it will not create the default domain.
*
* Call with hotplug lock held
*/
void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
struct sched_domain_attr *dattr_new)
{ int i, j, n;
int new_topology;
mutex_lock(&sched_domains_mutex);
/* always unregister in case we don't destroy any domains */
unregister_sched_domain_sysctl();
/* Let architecture update cpu core mappings. */
new_topology = arch_update_cpu_topology();
n = doms_new ? ndoms_new : 0;
/* Destroy deleted domains */
for (i = 0; i < ndoms_cur; i++) {
for (j = 0; j < n && !new_topology; j++) {
if (cpumask_equal(doms_cur[i], doms_new[j])
&& dattrs_equal(dattr_cur, i, dattr_new, j))
goto match1;
}
/* no match - a current sched domain not in new doms_new[] */
detach_destroy_domains(doms_cur[i]);
match1:
;
}
n = ndoms_cur;
if (doms_new == NULL) {
n = 0;
doms_new = &fallback_doms;
cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
WARN_ON_ONCE(dattr_new);
}
/* Build new domains */
for (i = 0; i < ndoms_new; i++) {
for (j = 0; j < n && !new_topology; j++) {
if (cpumask_equal(doms_new[i], doms_cur[j])
&& dattrs_equal(dattr_new, i, dattr_cur, j))
goto match2;
}
/* no match - add a new doms_new */
build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
match2:
;
}
/* Remember the new sched domains */
if (doms_cur != &fallback_doms)
free_sched_domains(doms_cur, ndoms_cur);
kfree(dattr_cur); /* kfree(NULL) is safe */
doms_cur = doms_new;
dattr_cur = dattr_new;
ndoms_cur = ndoms_new;
register_sched_domain_sysctl();
mutex_unlock(&sched_domains_mutex);
}
static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
/*
* Update cpusets according to cpu_active mask. If cpusets are
* disabled, cpuset_update_active_cpus() becomes a simple wrapper
* around partition_sched_domains().
*
* If we come here as part of a suspend/resume, don't touch cpusets because we
* want to restore it back to its original state upon resume anyway.
*/static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
switch (action) {
case CPU_ONLINE_FROZEN:
case CPU_DOWN_FAILED_FROZEN:
/*
* num_cpus_frozen tracks how many CPUs are involved in suspend
* resume sequence. As long as this is not the last online
* operation in the resume sequence, just build a single sched
* domain, ignoring cpusets.
*/
num_cpus_frozen--;
if (likely(num_cpus_frozen)) {
partition_sched_domains(1, NULL, NULL);
break;
}
/*
* This is the last CPU online operation. So fall through and
* restore the original sched domains by considering the
* cpuset configurations.
*/
case CPU_ONLINE:
cpuset_update_active_cpus(true);
break;
default:
return NOTIFY_DONE;
}
return NOTIFY_OK;
}
static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
unsigned long flags;
long cpu = (long)hcpu;
struct dl_bw *dl_b;
bool overflow;
int cpus;
switch (action) {
case CPU_DOWN_PREPARE:
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();
if (overflow)
return notifier_from_errno(-EBUSY);
cpuset_update_active_cpus(false);
break;
case CPU_DOWN_PREPARE_FROZEN:
num_cpus_frozen++;
partition_sched_domains(1, NULL, NULL);
break;
default:
return NOTIFY_DONE;
}
return NOTIFY_OK;
}
void __init sched_init_smp(void){
cpumask_var_t non_isolated_cpus;
alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
sched_init_numa();
/*
* There's no userspace yet to cause hotplug operations; hence all the
* cpu masks are stable and all blatant races in the below code cannot
* happen.
*/
mutex_lock(&sched_domains_mutex);
init_sched_domains(cpu_active_mask);
cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
if (cpumask_empty(non_isolated_cpus))
cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
mutex_unlock(&sched_domains_mutex);
hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
init_hrtick();
/* Move init over to a non-isolated CPU */
if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
BUG();
sched_init_granularity();
free_cpumask_var(non_isolated_cpus);
init_sched_rt_class();
init_sched_dl_class();
}
#else
void __init sched_init_smp(void)
{
sched_init_granularity();
}
#endif /* CONFIG_SMP */
int in_sched_functions(unsigned long addr)
{
return in_lock_functions(addr) ||
(addr >= (unsigned long)__sched_text_start
&& addr < (unsigned long)__sched_text_end);
}
#ifdef CONFIG_CGROUP_SCHED
/*
* Default task group.
* Every task in system belongs to this group at bootup.
*/
struct task_group root_task_group;
LIST_HEAD(task_groups);
/* Cacheline aligned slab cache for task_group */
static struct kmem_cache *task_group_cache __read_mostly;
#endif
DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
void __init sched_init(void)
{
int i, j;
unsigned long alloc_size = 0, ptr;
#ifdef CONFIG_FAIR_GROUP_SCHED
alloc_size += 2 * nr_cpu_ids * sizeof(void **);#endif
#ifdef CONFIG_RT_GROUP_SCHED
alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
if (alloc_size) {
ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
#ifdef CONFIG_FAIR_GROUP_SCHED
root_task_group.se = (struct sched_entity **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
root_task_group.cfs_rq = (struct cfs_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
root_task_group.rt_se = (struct sched_rt_entity **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
root_task_group.rt_rq = (struct rt_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#endif /* CONFIG_RT_GROUP_SCHED */
}
#ifdef CONFIG_CPUMASK_OFFSTACK
for_each_possible_cpu(i) {
per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
cpumask_size(), GFP_KERNEL, cpu_to_node(i));
}
#endif /* CONFIG_CPUMASK_OFFSTACK */
init_rt_bandwidth(&def_rt_bandwidth,
global_rt_period(), global_rt_runtime());
init_dl_bandwidth(&def_dl_bandwidth,
global_rt_period(), global_rt_runtime());
#ifdef CONFIG_SMP
init_defrootdomain();
#endif
#ifdef CONFIG_RT_GROUP_SCHED
init_rt_bandwidth(&root_task_group.rt_bandwidth,
global_rt_period(), global_rt_runtime());
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CGROUP_SCHED
task_group_cache = KMEM_CACHE(task_group, 0);
list_add(&root_task_group.list, &task_groups);
INIT_LIST_HEAD(&root_task_group.children);
INIT_LIST_HEAD(&root_task_group.siblings);
autogroup_init(&init_task);
#endif /* CONFIG_CGROUP_SCHED */
for_each_possible_cpu(i) {
struct rq *rq;
rq = cpu_rq(i);
raw_spin_lock_init(&rq->lock);
rq->nr_running = 0;
rq->calc_load_active = 0;
rq->calc_load_update = jiffies + LOAD_FREQ;
init_cfs_rq(&rq->cfs);
init_rt_rq(&rq->rt);
init_dl_rq(&rq->dl);
#ifdef CONFIG_FAIR_GROUP_SCHED
root_task_group.shares = ROOT_TASK_GROUP_LOAD;
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
/*
* How much cpu bandwidth does root_task_group get? *
* In case of task-groups formed thr' the cgroup filesystem, it
* gets 100% of the cpu resources in the system. This overall
* system cpu resource is divided among the tasks of
* root_task_group and its child task-groups in a fair manner,
* based on each entity's (task or task-group's) weight
* (se->load.weight).
*
* In other words, if root_task_group has 10 tasks of weight
* 1024) and two child groups A0 and A1 (of weight 1024 each),
* then A0's share of the cpu resource is:
*
* A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
*
* We achieve this by letting root_task_group's tasks sit
* directly in rq->cfs (i.e root_task_group->se[] = NULL).
*/
init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
#endif /* CONFIG_FAIR_GROUP_SCHED */
rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
#ifdef CONFIG_RT_GROUP_SCHED
init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
#endif
for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
rq->cpu_load[j] = 0;
rq->last_load_update_tick = jiffies;
#ifdef CONFIG_SMP
rq->sd = NULL;
rq->rd = NULL;
rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
rq->balance_callback = NULL;
rq->active_balance = 0;
rq->next_balance = jiffies;
rq->push_cpu = 0;
rq->cpu = i;
rq->online = 0;
rq->idle_stamp = 0;
rq->avg_idle = 2*sysctl_sched_migration_cost;
rq->max_idle_balance_cost = sysctl_sched_migration_cost;
INIT_LIST_HEAD(&rq->cfs_tasks);
rq_attach_root(rq, &def_root_domain);
#ifdef CONFIG_NO_HZ_COMMON
rq->nohz_flags = 0;
#endif
#ifdef CONFIG_NO_HZ_FULL
rq->last_sched_tick = 0;
#endif
#endif
init_rq_hrtick(rq);
atomic_set(&rq->nr_iowait, 0);
}
set_load_weight(&init_task);
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&init_task.preempt_notifiers);
#endif
/*
* The boot idle thread does lazy MMU switching as well:
*/
atomic_inc(&init_mm.mm_count);
enter_lazy_tlb(&init_mm, current);
/*
* During early bootup we pretend to be a normal task:
*/
current->sched_class = &fair_sched_class;
/*
* Make us the idle thread. Technically, schedule() should not be
* called from this thread, however somewhere below it might be,
* but because we are the idle thread, we just pick up running again
* when this runqueue becomes "idle".
*/
init_idle(current, smp_processor_id());
calc_load_update = jiffies + LOAD_FREQ;
#ifdef CONFIG_SMP
zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
/* May be allocated at isolcpus cmdline parse time */
if (cpu_isolated_map == NULL)
zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
idle_thread_set_boot_cpu();
set_cpu_rq_start_time();
#endif
init_sched_fair_class();
scheduler_running = 1;
}
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
static inline int preempt_count_equals(int preempt_offset)
{
int nested = preempt_count() + rcu_preempt_depth();
return (nested == preempt_offset);
}
void __might_sleep(const char *file, int line, int preempt_offset)
{
/*
* Blocking primitives will set (and therefore destroy) current->state,
* since we will exit with TASK_RUNNING make sure we enter with it,
* otherwise we will destroy state.
*/
WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
"do not call blocking ops when !TASK_RUNNING; "
"state=%lx set at [<%p>] %pS\n",
current->state,
(void *)current->task_state_change,
(void *)current->task_state_change);
___might_sleep(file, line, preempt_offset);
}
EXPORT_SYMBOL(__might_sleep);
void ___might_sleep(const char *file, int line, int preempt_offset)
{
static unsigned long prev_jiffy; /* ratelimiting */
rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
!is_idle_task(current)) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
prev_jiffy = jiffies;
printk(KERN_ERR
"BUG: sleeping function called from invalid context at %s:%d\n", file, line);
printk(KERN_ERR
"in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
in_atomic(), irqs_disabled(),
current->pid, current->comm);
if (task_stack_end_corrupted(current))
printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
debug_show_held_locks(current);
if (irqs_disabled())
print_irqtrace_events(current);
#ifdef CONFIG_DEBUG_PREEMPT
if (!preempt_count_equals(preempt_offset)) {
pr_err("Preemption disabled at:");
print_ip_sym(current->preempt_disable_ip);
pr_cont("\n");
}
#endif
dump_stack();
}
EXPORT_SYMBOL(___might_sleep);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
void normalize_rt_tasks(void)
{
struct task_struct *g, *p;
struct sched_attr attr = {
.sched_policy = SCHED_NORMAL,
};
read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
/*
* Only normalize user tasks:
*/
if (p->flags & PF_KTHREAD)
continue;
p->se.exec_start = 0;
#ifdef CONFIG_SCHEDSTATS
p->se.statistics.wait_start = 0;
p->se.statistics.sleep_start = 0;
p->se.statistics.block_start = 0;
#endif
if (!dl_task(p) && !rt_task(p)) {
/*
* Renice negative nice level userspace
* tasks back to 0:
*/
if (task_nice(p) < 0)
set_user_nice(p, 0);
continue;
}
__sched_setscheduler(p, &attr, false, false);
}
read_unlock(&tasklist_lock);
}
#endif /* CONFIG_MAGIC_SYSRQ */
#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
/*
* These functions are only useful for the IA64 MCA handling, or kdb.
*
* They can only be called when the whole system has been
* stopped - every CPU needs to be quiescent, and no scheduling * activity can take place. Using them for anything else would
* be a serious bug, and as a result, they aren't even visible
* under any other configuration.
*/
/**
* curr_task - return the current task for a given cpu.
* @cpu: the processor in question.
*
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
*
* Return: The current task for @cpu.
*/
struct task_struct *curr_task(int cpu)
{
return cpu_curr(cpu);
}
#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
#ifdef CONFIG_IA64
/**
* set_curr_task - set the current task for a given cpu.
* @cpu: the processor in question.
* @p: the task pointer to set.
*
* Description: This function must only be used when non-maskable interrupts
* are serviced on a separate stack. It allows the architecture to switch the
* notion of the current task on a cpu in a non-blocking manner. This function
* must be called with all CPU's synchronized, and interrupts disabled, the
* and caller must save the original value of the current task (see
* curr_task() above) and restore that value before reenabling interrupts and
* re-starting the system.
*
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
*/
void set_curr_task(int cpu, struct task_struct *p)
{
cpu_curr(cpu) = p;
}
#endif
#ifdef CONFIG_CGROUP_SCHED
/* task_group_lock serializes the addition/removal of task groups */
static DEFINE_SPINLOCK(task_group_lock);
static void free_sched_group(struct task_group *tg)
{
free_fair_sched_group(tg);
free_rt_sched_group(tg);
autogroup_free(tg);
kmem_cache_free(task_group_cache, tg);
}
/* allocate runqueue etc for a new task group */
struct task_group *sched_create_group(struct task_group *parent)
{
struct task_group *tg;
tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
if (!tg)
return ERR_PTR(-ENOMEM);
if (!alloc_fair_sched_group(tg, parent))
goto err;
if (!alloc_rt_sched_group(tg, parent))
goto err;
return tg;
err:
free_sched_group(tg);
return ERR_PTR(-ENOMEM);
}
void sched_online_group(struct task_group *tg, struct task_group *parent)
{
unsigned long flags;
spin_lock_irqsave(&task_group_lock, flags);
list_add_rcu(&tg->list, &task_groups);
WARN_ON(!parent); /* root should already exist */
tg->parent = parent;
INIT_LIST_HEAD(&tg->children);
list_add_rcu(&tg->siblings, &parent->children);
spin_unlock_irqrestore(&task_group_lock, flags);
}
/* rcu callback to free various structures associated with a task group */
static void free_sched_group_rcu(struct rcu_head *rhp)
{
/* now it should be safe to free those cfs_rqs */
free_sched_group(container_of(rhp, struct task_group, rcu));
}
/* Destroy runqueue etc associated with a task group */
void sched_destroy_group(struct task_group *tg)
{
/* wait for possible concurrent references to cfs_rqs complete */
call_rcu(&tg->rcu, free_sched_group_rcu);
}
void sched_offline_group(struct task_group *tg)
{
unsigned long flags;
/* end participation in shares distribution */
unregister_fair_sched_group(tg);
spin_lock_irqsave(&task_group_lock, flags);
list_del_rcu(&tg->list);
list_del_rcu(&tg->siblings);
spin_unlock_irqrestore(&task_group_lock, flags);
}
/* change task's runqueue when it moves between groups.
* The caller of this function should have put the task in its new group
* by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
* reflect its new group.
*/
void sched_move_task(struct task_struct *tsk)
{
struct task_group *tg;
int queued, running;
unsigned long flags;
struct rq *rq;
rq = task_rq_lock(tsk, &flags);
running = task_current(rq, tsk);
queued = task_on_rq_queued(tsk);
if (queued)
dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
if (unlikely(running))
put_prev_task(rq, tsk);
/*
* All callers are synchronized by task_rq_lock(); we do not use RCU
* which is pointless here. Thus, we pass "true" to task_css_check()
* to prevent lockdep warnings.
*/
tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
struct task_group, css);
tg = autogroup_task_group(tsk, tg);
tsk->sched_task_group = tg;
#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->task_move_group)
tsk->sched_class->task_move_group(tsk);
else
#endif
set_task_rq(tsk, task_cpu(tsk));
if (unlikely(running))
tsk->sched_class->set_curr_task(rq);
if (queued)
enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
task_rq_unlock(rq, tsk, &flags);
}
#endif /* CONFIG_CGROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
/*
* Ensure that the real time constraints are schedulable.
*/
static DEFINE_MUTEX(rt_constraints_mutex);
/* Must be called with tasklist_lock held */
static inline int tg_has_rt_tasks(struct task_group *tg)
{
struct task_struct *g, *p;
/*
* Autogroups do not have RT tasks; see autogroup_create().
*/
if (task_group_is_autogroup(tg))
return 0;
for_each_process_thread(g, p) {
if (rt_task(p) && task_group(p) == tg)
return 1;
}
return 0;
}
struct rt_schedulable_data {
struct task_group *tg;
u64 rt_period;
u64 rt_runtime;
};
static int tg_rt_schedulable(struct task_group *tg, void *data)
{
struct rt_schedulable_data *d = data;
struct task_group *child;
unsigned long total, sum = 0;
u64 period, runtime;
period = ktime_to_ns(tg->rt_bandwidth.rt_period);
runtime = tg->rt_bandwidth.rt_runtime;
if (tg == d->tg) {
period = d->rt_period; runtime = d->rt_runtime;
}
/*
* Cannot have more runtime than the period.
*/
if (runtime > period && runtime != RUNTIME_INF)
return -EINVAL;
/*
* Ensure we don't starve existing RT tasks.
*/
if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
return -EBUSY;
total = to_ratio(period, runtime);
/*
* Nobody can have more than the global setting allows.
*/
if (total > to_ratio(global_rt_period(), global_rt_runtime()))
return -EINVAL;
/*
* The sum of our children's runtime should not exceed our own.
*/
list_for_each_entry_rcu(child, &tg->children, siblings) {
period = ktime_to_ns(child->rt_bandwidth.rt_period);
runtime = child->rt_bandwidth.rt_runtime;
if (child == d->tg) {
period = d->rt_period;
runtime = d->rt_runtime;
}
sum += to_ratio(period, runtime);
}
if (sum > total)
return -EINVAL;
return 0;
}
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
{
int ret;
struct rt_schedulable_data data = {
.tg = tg,
.rt_period = period,
.rt_runtime = runtime,
};
rcu_read_lock();
ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
rcu_read_unlock();
return ret;
}
static int tg_set_rt_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime)
{
int i, err = 0;
/*
* Disallowing the root group RT runtime is BAD, it would disallow the
* kernel creating (and or operating) RT threads.
*/ if (tg == &root_task_group && rt_runtime == 0)
return -EINVAL;
/* No period doesn't make any sense. */
if (rt_period == 0)
return -EINVAL;
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
err = __rt_schedulable(tg, rt_period, rt_runtime);
if (err)
goto unlock;
raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
tg->rt_bandwidth.rt_runtime = rt_runtime;
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = tg->rt_rq[i];
raw_spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = rt_runtime;
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
unlock:
read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);
return err;
}
static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
{
u64 rt_runtime, rt_period;
rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
if (rt_runtime_us < 0)
rt_runtime = RUNTIME_INF;
return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
}
static long sched_group_rt_runtime(struct task_group *tg)
{
u64 rt_runtime_us;
if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
return -1;
rt_runtime_us = tg->rt_bandwidth.rt_runtime;
do_div(rt_runtime_us, NSEC_PER_USEC);
return rt_runtime_us;
}
static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
{
u64 rt_runtime, rt_period;
rt_period = rt_period_us * NSEC_PER_USEC;
rt_runtime = tg->rt_bandwidth.rt_runtime;
return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
}
static long sched_group_rt_period(struct task_group *tg)
{
u64 rt_period_us;
rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
do_div(rt_period_us, NSEC_PER_USEC);
return rt_period_us;
}
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
static int sched_rt_global_constraints(void)
{
int ret = 0;
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
ret = __rt_schedulable(NULL, 0, 0);
read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);
return ret;
}
static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
{
/* Don't accept realtime tasks when there is no way for them to run */
if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
return 0;
return 1;
}
#else /* !CONFIG_RT_GROUP_SCHED */
static int sched_rt_global_constraints(void)
{
unsigned long flags;
int i, ret = 0;
raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = &cpu_rq(i)->rt;
raw_spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = global_rt_runtime();
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
return ret;
}
#endif /* CONFIG_RT_GROUP_SCHED */
static 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;
}
static 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();
}
}
static int sched_rt_global_validate(void)
{
if (sysctl_sched_rt_period <= 0)
return -EINVAL;
if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
(sysctl_sched_rt_runtime > sysctl_sched_rt_period))
return -EINVAL;
return 0;
}
static void sched_rt_do_global(void)
{
def_rt_bandwidth.rt_runtime = global_rt_runtime();
def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
}
int sched_rt_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int old_period, old_runtime;
static DEFINE_MUTEX(mutex);
int ret;
mutex_lock(&mutex); old_period = sysctl_sched_rt_period;
old_runtime = sysctl_sched_rt_runtime;
ret = proc_dointvec(table, write, buffer, lenp, ppos);
if (!ret && write) {
ret = sched_rt_global_validate();
if (ret)
goto undo;
ret = sched_dl_global_validate();
if (ret)
goto undo;
ret = sched_rt_global_constraints();
if (ret)
goto undo;
sched_rt_do_global();
sched_dl_do_global();
}
if (0) {
undo:
sysctl_sched_rt_period = old_period;
sysctl_sched_rt_runtime = old_runtime;
}
mutex_unlock(&mutex);
return ret;
}
int sched_rr_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int ret;
static DEFINE_MUTEX(mutex);
mutex_lock(&mutex);
ret = proc_dointvec(table, write, buffer, lenp, ppos);
/* make sure that internally we keep jiffies */
/* also, writing zero resets timeslice to default */
if (!ret && write) {
sched_rr_timeslice = sched_rr_timeslice <= 0 ?
RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
}
mutex_unlock(&mutex);
return ret;
}
#ifdef CONFIG_CGROUP_SCHED
static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct task_group, css) : NULL;
}
static struct cgroup_subsys_state *
cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct task_group *parent = css_tg(parent_css);
struct task_group *tg;
if (!parent) {
/* This is early initialization for the top cgroup */
return &root_task_group.css;
}
tg = sched_create_group(parent);
if (IS_ERR(tg)) return ERR_PTR(-ENOMEM);
return &tg->css;
}
static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
{
struct task_group *tg = css_tg(css);
struct task_group *parent = css_tg(css->parent);
if (parent)
sched_online_group(tg, parent);
return 0;
}
static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
{
struct task_group *tg = css_tg(css);
sched_destroy_group(tg);
}
static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
{
struct task_group *tg = css_tg(css);
sched_offline_group(tg);
}
static void cpu_cgroup_fork(struct task_struct *task)
{
sched_move_task(task);
}
static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
{
struct task_struct *task;
struct cgroup_subsys_state *css;
cgroup_taskset_for_each(task, css, tset) {
#ifdef CONFIG_RT_GROUP_SCHED
if (!sched_rt_can_attach(css_tg(css), task))
return -EINVAL;
#else
/* We don't support RT-tasks being in separate groups */
if (task->sched_class != &fair_sched_class)
return -EINVAL;
#endif
}
return 0;
}
static void cpu_cgroup_attach(struct cgroup_taskset *tset)
{
struct task_struct *task;
struct cgroup_subsys_state *css;
cgroup_taskset_for_each(task, css, tset)
sched_move_task(task);
}
#ifdef CONFIG_FAIR_GROUP_SCHED
static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
struct cftype *cftype, u64 shareval)
{
return sched_group_set_shares(css_tg(css), scale_load(shareval));
}
static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
struct cftype *cft){
struct task_group *tg = css_tg(css);
return (u64) scale_load_down(tg->shares);
}
#ifdef CONFIG_CFS_BANDWIDTH
static DEFINE_MUTEX(cfs_constraints_mutex);
const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
{
int i, ret = 0, runtime_enabled, runtime_was_enabled;
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
if (tg == &root_task_group)
return -EINVAL;
/*
* Ensure we have at some amount of bandwidth every period. This is
* to prevent reaching a state of large arrears when throttled via
* entity_tick() resulting in prolonged exit starvation.
*/
if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
return -EINVAL;
/*
* Likewise, bound things on the otherside by preventing insane quota
* periods. This also allows us to normalize in computing quota
* feasibility.
*/
if (period > max_cfs_quota_period)
return -EINVAL;
/*
* Prevent race between setting of cfs_rq->runtime_enabled and
* unthrottle_offline_cfs_rqs().
*/
get_online_cpus();
mutex_lock(&cfs_constraints_mutex);
ret = __cfs_schedulable(tg, period, quota);
if (ret)
goto out_unlock;
runtime_enabled = quota != RUNTIME_INF;
runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
/*
* If we need to toggle cfs_bandwidth_used, off->on must occur
* before making related changes, and on->off must occur afterwards
*/
if (runtime_enabled && !runtime_was_enabled)
cfs_bandwidth_usage_inc();
raw_spin_lock_irq(&cfs_b->lock);
cfs_b->period = ns_to_ktime(period);
cfs_b->quota = quota;
__refill_cfs_bandwidth_runtime(cfs_b);
/* restart the period timer (if active) to handle new period expiry */
if (runtime_enabled)
start_cfs_bandwidth(cfs_b);
raw_spin_unlock_irq(&cfs_b->lock);
for_each_online_cpu(i) {
struct cfs_rq *cfs_rq = tg->cfs_rq[i];
struct rq *rq = cfs_rq->rq;
raw_spin_lock_irq(&rq->lock);
cfs_rq->runtime_enabled = runtime_enabled;
cfs_rq->runtime_remaining = 0;
if (cfs_rq->throttled)
unthrottle_cfs_rq(cfs_rq);
raw_spin_unlock_irq(&rq->lock);
}
if (runtime_was_enabled && !runtime_enabled)
cfs_bandwidth_usage_dec();
out_unlock:
mutex_unlock(&cfs_constraints_mutex);
put_online_cpus();
return ret;
}
int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
{
u64 quota, period;
period = ktime_to_ns(tg->cfs_bandwidth.period);
if (cfs_quota_us < 0)
quota = RUNTIME_INF;
else
quota = (u64)cfs_quota_us * NSEC_PER_USEC;
return tg_set_cfs_bandwidth(tg, period, quota);
}
long tg_get_cfs_quota(struct task_group *tg)
{
u64 quota_us;
if (tg->cfs_bandwidth.quota == RUNTIME_INF)
return -1;
quota_us = tg->cfs_bandwidth.quota;
do_div(quota_us, NSEC_PER_USEC);
return quota_us;
}
int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
{
u64 quota, period;
period = (u64)cfs_period_us * NSEC_PER_USEC;
quota = tg->cfs_bandwidth.quota;
return tg_set_cfs_bandwidth(tg, period, quota);
}
long tg_get_cfs_period(struct task_group *tg)
{
u64 cfs_period_us;
cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
do_div(cfs_period_us, NSEC_PER_USEC);
return cfs_period_us;
}
static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return tg_get_cfs_quota(css_tg(css));
}
static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, struct cftype *cftype, s64 cfs_quota_us)
{
return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
}
static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return tg_get_cfs_period(css_tg(css));
}
static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
struct cftype *cftype, u64 cfs_period_us)
{
return tg_set_cfs_period(css_tg(css), cfs_period_us);
}
struct cfs_schedulable_data {
struct task_group *tg;
u64 period, quota;
};
/*
* normalize group quota/period to be quota/max_period
* note: units are usecs
*/
static u64 normalize_cfs_quota(struct task_group *tg,
struct cfs_schedulable_data *d)
{
u64 quota, period;
if (tg == d->tg) {
period = d->period;
quota = d->quota;
} else {
period = tg_get_cfs_period(tg);
quota = tg_get_cfs_quota(tg);
}
/* note: these should typically be equivalent */
if (quota == RUNTIME_INF || quota == -1)
return RUNTIME_INF;
return to_ratio(period, quota);
}
static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
{
struct cfs_schedulable_data *d = data;
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
s64 quota = 0, parent_quota = -1;
if (!tg->parent) {
quota = RUNTIME_INF;
} else {
struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
quota = normalize_cfs_quota(tg, d);
parent_quota = parent_b->hierarchical_quota;
/*
* ensure max(child_quota) <= parent_quota, inherit when no
* limit is set
*/
if (quota == RUNTIME_INF)
quota = parent_quota;
else if (parent_quota != RUNTIME_INF && quota > parent_quota)
return -EINVAL;
}
cfs_b->hierarchical_quota = quota;
return 0;
}
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
{
int ret;
struct cfs_schedulable_data data = {
.tg = tg,
.period = period,
.quota = quota,
};
if (quota != RUNTIME_INF) {
do_div(data.period, NSEC_PER_USEC);
do_div(data.quota, NSEC_PER_USEC);
}
rcu_read_lock();
ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
rcu_read_unlock();
return ret;
}
static int cpu_stats_show(struct seq_file *sf, void *v)
{
struct task_group *tg = css_tg(seq_css(sf));
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
return 0;
}
#endif /* CONFIG_CFS_BANDWIDTH */
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
struct cftype *cft, s64 val)
{
return sched_group_set_rt_runtime(css_tg(css), val);
}
static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return sched_group_rt_runtime(css_tg(css));
}
static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
struct cftype *cftype, u64 rt_period_us)
{
return sched_group_set_rt_period(css_tg(css), rt_period_us);
}
static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return sched_group_rt_period(css_tg(css));
}
#endif /* CONFIG_RT_GROUP_SCHED */
static struct cftype cpu_files[] = {
#ifdef CONFIG_FAIR_GROUP_SCHED
{
.name = "shares",
.read_u64 = cpu_shares_read_u64, .write_u64 = cpu_shares_write_u64,
},
#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
.name = "cfs_quota_us",
.read_s64 = cpu_cfs_quota_read_s64,
.write_s64 = cpu_cfs_quota_write_s64,
},
{
.name = "cfs_period_us",
.read_u64 = cpu_cfs_period_read_u64,
.write_u64 = cpu_cfs_period_write_u64,
},
{
.name = "stat",
.seq_show = cpu_stats_show,
},
#endif
#ifdef CONFIG_RT_GROUP_SCHED
{
.name = "rt_runtime_us",
.read_s64 = cpu_rt_runtime_read,
.write_s64 = cpu_rt_runtime_write,
},
{
.name = "rt_period_us",
.read_u64 = cpu_rt_period_read_uint,
.write_u64 = cpu_rt_period_write_uint,
},
#endif
{ } /* terminate */
};
struct cgroup_subsys cpu_cgrp_subsys = {
.css_alloc = cpu_cgroup_css_alloc,
.css_free = cpu_cgroup_css_free,
.css_online = cpu_cgroup_css_online,
.css_offline = cpu_cgroup_css_offline,
.fork = cpu_cgroup_fork,
.can_attach = cpu_cgroup_can_attach,
.attach = cpu_cgroup_attach,
.legacy_cftypes = cpu_files,
.early_init = 1,
};
#endif /* CONFIG_CGROUP_SCHED */
void dump_cpu_task(int cpu)
{
pr_info("Task dump for CPU %d:\n", cpu);
sched_show_task(cpu_curr(cpu));
}
/*
* Nice levels are multiplicative, with a gentle 10% change for every
* nice level changed. I.e. when a CPU-bound task goes from nice 0 to
* nice 1, it will get ~10% less CPU time than another CPU-bound task
* that remained on nice 0.
*
* The "10% effect" is relative and cumulative: from _any_ nice level,
* if you go up 1 level, it's -10% CPU usage, if you go down 1 level
* it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
* If a task goes up by ~10% and another task goes down by ~10% then
* the relative distance between them is ~25%.)
*/
const int sched_prio_to_weight[40] = {
/* -20 */ 88761, 71755, 56483, 46273, 36291,
/* -15 */ 29154, 23254, 18705, 14949, 11916,
/* -10 */ 9548, 7620, 6100, 4904, 3906, /* -5 */ 3121, 2501, 1991, 1586, 1277,
/* 0 */ 1024, 820, 655, 526, 423,
/* 5 */ 335, 272, 215, 172, 137,
/* 10 */ 110, 87, 70, 56, 45,
/* 15 */ 36, 29, 23, 18, 15,
};
/*
* Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
*
* In cases where the weight does not change often, we can use the
* precalculated inverse to speed up arithmetics by turning divisions
* into multiplications:
*/
const u32 sched_prio_to_wmult[40] = {
/* -20 */ 48388, 59856, 76040, 92818, 118348,
/* -15 */ 147320, 184698, 229616, 287308, 360437,
/* -10 */ 449829, 563644, 704093, 875809, 1099582,
/* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
/* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
/* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
/* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};