/*
* kernel/sched/core.c
*
- * Kernel scheduler and related syscalls
+ * Core kernel scheduler code 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 <linux/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/sched.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 <linux/frame.h>
+
+#include <linux/blkdev.h>
+#include <linux/kprobes.h>
+#include <linux/mmu_context.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
#include <linux/prefetch.h>
-#include <linux/mutex.h>
+#include <linux/profile.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
#include <asm/switch_to.h>
#include <asm/tlb.h>
-#include <asm/irq_regs.h>
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#endif
#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
*/
const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
/*
- * period over which we measure -rt task cpu usage in us.
+ * period over which we measure -rt task CPU usage in us.
* default: 1s
*/
unsigned int sysctl_sched_rt_period = 1000000;
*/
int sysctl_sched_rt_runtime = 950000;
-/* cpus with isolated domains */
+/* CPUs with isolated domains */
cpumask_var_t cpu_isolated_map;
/*
rq = task_rq(p);
raw_spin_lock(&rq->lock);
if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
- rf->cookie = lockdep_pin_lock(&rq->lock);
+ rq_pin_lock(rq, rf);
return rq;
}
raw_spin_unlock(&rq->lock);
* If we observe the old cpu in task_rq_lock, the acquire of
* the old rq->lock will fully serialize against the stores.
*
- * If we observe the new cpu in task_rq_lock, the acquire will
+ * If we observe the new CPU in task_rq_lock, the acquire will
* pair with the WMB to ensure we must then also see migrating.
*/
if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
- rf->cookie = lockdep_pin_lock(&rq->lock);
+ rq_pin_lock(rq, rf);
return rq;
}
raw_spin_unlock(&rq->lock);
}
}
+/*
+ * RQ-clock updating methods:
+ */
+
+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 update_rq_clock(struct rq *rq)
+{
+ s64 delta;
+
+ lockdep_assert_held(&rq->lock);
+
+ if (rq->clock_update_flags & RQCF_ACT_SKIP)
+ return;
+
+#ifdef CONFIG_SCHED_DEBUG
+ rq->clock_update_flags |= RQCF_UPDATED;
+#endif
+ delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
+ if (delta < 0)
+ return;
+ rq->clock += delta;
+ update_rq_clock_task(rq, delta);
+}
+
+
#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
task = container_of(node, struct task_struct, wake_q);
BUG_ON(!task);
- /* task can safely be re-inserted now */
+ /* Task can safely be re-inserted now: */
node = node->next;
task->wake_q.next = NULL;
#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.
+ * 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).
+ * 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)
{
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
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 };
};
/*
- * Move (not current) task off this cpu, onto dest cpu. We're doing
+ * Move (not current) task off this CPU, onto the destination 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).
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.
+ * The original target CPU might have gone down and we might
+ * be on another CPU but it doesn't matter.
*/
local_irq_disable();
/*
if (p->flags & PF_KTHREAD) {
/*
* For kernel threads that do indeed end up on online &&
- * !active we want to ensure they are strict per-cpu threads.
+ * !active we want to ensure they are strict per-CPU threads.
*/
WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) &&
!cpumask_intersects(new_mask, cpu_active_mask) &&
* OK, since we're going to drop the lock immediately
* afterwards anyway.
*/
- lockdep_unpin_lock(&rq->lock, rf.cookie);
+ rq_unpin_lock(rq, &rf);
rq = move_queued_task(rq, p, dest_cpu);
- lockdep_repin_lock(&rq->lock, rf.cookie);
+ rq_repin_lock(rq, &rf);
}
out:
task_rq_unlock(rq, p, &rf);
/*
* 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 target instead of where it really is.
+ * previous CPU our target instead of where it really is.
*/
p->wake_cpu = cpu;
}
*
* - on cpu-up we allow per-cpu kthreads on the online && !active cpu,
* see __set_cpus_allowed_ptr(). At this point the newly online
- * cpu isn't yet part of the sched domains, and balancing will not
+ * CPU isn't yet part of the sched domains, and balancing will not
* see it.
*
- * - on cpu-down we clear cpu_active() to mask the sched domains and
+ * - on CPU-down we clear cpu_active() to mask the sched domains and
* avoid the load balancer to place new tasks on the to be removed
- * cpu. Existing tasks will remain running there and will be taken
+ * CPU. Existing tasks will remain running there and will be taken
* off.
*
* This means that fallback selection must not select !active CPUs.
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 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);
state = possible;
break;
}
- /* fall-through */
+ /* Fall-through */
case possible:
do_set_cpus_allowed(p, cpu_possible_mask);
state = fail;
/*
* 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.
+ * CPU.
*
* Since this is common to all placement strategies, this lives here.
*
activate_task(rq, p, en_flags);
p->on_rq = TASK_ON_RQ_QUEUED;
- /* if a worker is waking up, notify workqueue */
+ /* If a worker is waking up, notify the 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,
- struct pin_cookie cookie)
+ struct rq_flags *rf)
{
check_preempt_curr(rq, p, wake_flags);
p->state = TASK_RUNNING;
* 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, cookie);
+ rq_unpin_lock(rq, rf);
p->sched_class->task_woken(rq, p);
- lockdep_repin_lock(&rq->lock, cookie);
+ rq_repin_lock(rq, rf);
}
if (rq->idle_stamp) {
static void
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
- struct pin_cookie cookie)
+ struct rq_flags *rf)
{
int en_flags = ENQUEUE_WAKEUP;
#endif
ttwu_activate(rq, p, en_flags);
- ttwu_do_wakeup(rq, p, wake_flags, cookie);
+ ttwu_do_wakeup(rq, p, wake_flags, rf);
}
/*
if (task_on_rq_queued(p)) {
/* check_preempt_curr() may use rq clock */
update_rq_clock(rq);
- ttwu_do_wakeup(rq, p, wake_flags, rf.cookie);
+ ttwu_do_wakeup(rq, p, wake_flags, &rf);
ret = 1;
}
__task_rq_unlock(rq, &rf);
{
struct rq *rq = this_rq();
struct llist_node *llist = llist_del_all(&rq->wake_list);
- struct pin_cookie cookie;
struct task_struct *p;
unsigned long flags;
+ struct rq_flags rf;
if (!llist)
return;
raw_spin_lock_irqsave(&rq->lock, flags);
- cookie = lockdep_pin_lock(&rq->lock);
+ rq_pin_lock(rq, &rf);
while (llist) {
int wake_flags = 0;
if (p->sched_remote_wakeup)
wake_flags = WF_MIGRATED;
- ttwu_do_activate(rq, p, wake_flags, cookie);
+ ttwu_do_activate(rq, p, wake_flags, &rf);
}
- lockdep_unpin_lock(&rq->lock, cookie);
+ rq_unpin_lock(rq, &rf);
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
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 */
+ /* Else CPU is not idle, do nothing here: */
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
{
struct rq *rq = cpu_rq(cpu);
- struct pin_cookie cookie;
+ struct rq_flags rf;
#if defined(CONFIG_SMP)
if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
- sched_clock_cpu(cpu); /* sync clocks x-cpu */
+ sched_clock_cpu(cpu); /* Sync clocks across CPUs */
ttwu_queue_remote(p, cpu, wake_flags);
return;
}
#endif
raw_spin_lock(&rq->lock);
- cookie = lockdep_pin_lock(&rq->lock);
- ttwu_do_activate(rq, p, wake_flags, cookie);
- lockdep_unpin_lock(&rq->lock, cookie);
+ rq_pin_lock(rq, &rf);
+ ttwu_do_activate(rq, p, wake_flags, &rf);
+ rq_unpin_lock(rq, &rf);
raw_spin_unlock(&rq->lock);
}
* 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].
+ * 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:
*
*
* 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
+ * Note: the CPU doing B need not be c0 or c1
*
* Example:
*
trace_sched_waking(p);
- success = 1; /* we're going to change ->state */
+ /* We're going to change ->state: */
+ success = 1;
cpu = task_cpu(p);
/*
smp_rmb();
/*
- * If the owning (remote) cpu is still in the middle of schedule() with
+ * 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().
p->sched_contributes_to_load = !!task_contributes_to_load(p);
p->state = TASK_WAKING;
+ if (p->in_iowait) {
+ delayacct_blkio_end();
+ atomic_dec(&task_rq(p)->nr_iowait);
+ }
+
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);
}
+
+#else /* CONFIG_SMP */
+
+ if (p->in_iowait) {
+ delayacct_blkio_end();
+ atomic_dec(&task_rq(p)->nr_iowait);
+ }
+
#endif /* CONFIG_SMP */
ttwu_queue(p, cpu, wake_flags);
* 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 pin_cookie cookie)
+static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf)
{
struct rq *rq = task_rq(p);
* disabled avoiding further scheduler activity on it and we've
* not yet picked a replacement task.
*/
- lockdep_unpin_lock(&rq->lock, cookie);
+ rq_unpin_lock(rq, rf);
raw_spin_unlock(&rq->lock);
raw_spin_lock(&p->pi_lock);
raw_spin_lock(&rq->lock);
- lockdep_repin_lock(&rq->lock, cookie);
+ rq_repin_lock(rq, rf);
}
if (!(p->state & TASK_NORMAL))
trace_sched_waking(p);
- if (!task_on_rq_queued(p))
+ if (!task_on_rq_queued(p)) {
+ if (p->in_iowait) {
+ delayacct_blkio_end();
+ atomic_dec(&rq->nr_iowait);
+ }
ttwu_activate(rq, p, ENQUEUE_WAKEUP);
+ }
- ttwu_do_wakeup(rq, p, 0, cookie);
+ ttwu_do_wakeup(rq, p, 0, rf);
ttwu_stat(p, smp_processor_id(), 0);
out:
raw_spin_unlock(&p->pi_lock);
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
/*
- * We're setting the cpu for the first time, we don't migrate,
+ * We're setting the CPU for the first time, we don't migrate,
* so use __set_task_cpu().
*/
__set_task_cpu(p, cpu);
/*
* 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
+ * - any previously selected CPU might disappear through hotplug
*
* Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
* as we're not fully set-up yet.
__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
#endif
rq = __task_rq_lock(p, &rf);
+ update_rq_clock(rq);
post_init_entity_util_avg(&p->se);
activate_task(rq, p, 0);
* Nothing relies on rq->lock after this, so its fine to
* drop it.
*/
- lockdep_unpin_lock(&rq->lock, rf.cookie);
+ rq_unpin_lock(rq, &rf);
p->sched_class->task_woken(rq, p);
- lockdep_repin_lock(&rq->lock, rf.cookie);
+ rq_repin_lock(rq, &rf);
}
#endif
task_rq_unlock(rq, p, &rf);
*/
static __always_inline struct rq *
context_switch(struct rq *rq, struct task_struct *prev,
- struct task_struct *next, struct pin_cookie cookie)
+ struct task_struct *next, struct rq_flags *rf)
{
struct mm_struct *mm, *oldmm;
prev->active_mm = NULL;
rq->prev_mm = oldmm;
}
+
+ rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
+
/*
* 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, cookie);
+ rq_unpin_lock(rq, rf);
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
/* Here we just switch the register state and the stack. */
}
/*
- * Check if only the current task is running on the cpu.
+ * 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
return sum;
}
+/*
+ * IO-wait accounting, and how its mostly bollocks (on SMP).
+ *
+ * The idea behind IO-wait account is to account the idle time that we could
+ * have spend running if it were not for IO. That is, if we were to improve the
+ * storage performance, we'd have a proportional reduction in IO-wait time.
+ *
+ * This all works nicely on UP, where, when a task blocks on IO, we account
+ * idle time as IO-wait, because if the storage were faster, it could've been
+ * running and we'd not be idle.
+ *
+ * This has been extended to SMP, by doing the same for each CPU. This however
+ * is broken.
+ *
+ * Imagine for instance the case where two tasks block on one CPU, only the one
+ * CPU will have IO-wait accounted, while the other has regular idle. Even
+ * though, if the storage were faster, both could've ran at the same time,
+ * utilising both CPUs.
+ *
+ * This means, that when looking globally, the current IO-wait accounting on
+ * SMP is a lower bound, by reason of under accounting.
+ *
+ * Worse, since the numbers are provided per CPU, they are sometimes
+ * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
+ * associated with any one particular CPU, it can wake to another CPU than it
+ * blocked on. This means the per CPU IO-wait number is meaningless.
+ *
+ * Task CPU affinities can make all that even more 'interesting'.
+ */
+
unsigned long nr_iowait(void)
{
unsigned long i, sum = 0;
return sum;
}
+/*
+ * Consumers of these two interfaces, like for example the cpufreq menu
+ * governor are using nonsensical data. Boosting frequency for a CPU that has
+ * IO-wait which might not even end up running the task when it does become
+ * runnable.
+ */
+
unsigned long nr_iowait_cpu(int cpu)
{
struct rq *this = cpu_rq(cpu);
* 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
+ * 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.
* Pick up the highest-prio task:
*/
static inline struct task_struct *
-pick_next_task(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)
+pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
{
- const struct sched_class *class = &fair_sched_class;
+ const struct sched_class *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, cookie);
+ if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
+ p = fair_sched_class.pick_next_task(rq, prev, rf);
if (unlikely(p == RETRY_TASK))
goto again;
- /* assumes fair_sched_class->next == idle_sched_class */
+ /* Assumes fair_sched_class->next == idle_sched_class */
if (unlikely(!p))
- p = idle_sched_class.pick_next_task(rq, prev, cookie);
+ p = idle_sched_class.pick_next_task(rq, prev, rf);
return p;
}
again:
for_each_class(class) {
- p = class->pick_next_task(rq, prev, cookie);
+ p = class->pick_next_task(rq, prev, rf);
if (p) {
if (unlikely(p == RETRY_TASK))
goto again;
}
}
- BUG(); /* the idle class will always have a runnable task */
+ /* The idle class should always have a runnable task: */
+ BUG();
}
/*
{
struct task_struct *prev, *next;
unsigned long *switch_count;
- struct pin_cookie cookie;
+ struct rq_flags rf;
struct rq *rq;
int cpu;
*/
smp_mb__before_spinlock();
raw_spin_lock(&rq->lock);
- cookie = lockdep_pin_lock(&rq->lock);
+ rq_pin_lock(rq, &rf);
- rq->clock_skip_update <<= 1; /* promote REQ to ACT */
+ /* Promote REQ to ACT */
+ rq->clock_update_flags <<= 1;
switch_count = &prev->nivcsw;
if (!preempt && prev->state) {
deactivate_task(rq, prev, DEQUEUE_SLEEP);
prev->on_rq = 0;
+ if (prev->in_iowait) {
+ atomic_inc(&rq->nr_iowait);
+ delayacct_blkio_start();
+ }
+
/*
* If a worker went to sleep, notify and ask workqueue
* whether it wants to wake up a task to maintain
to_wakeup = wq_worker_sleeping(prev);
if (to_wakeup)
- try_to_wake_up_local(to_wakeup, cookie);
+ try_to_wake_up_local(to_wakeup, &rf);
}
}
switch_count = &prev->nvcsw;
if (task_on_rq_queued(prev))
update_rq_clock(rq);
- next = pick_next_task(rq, prev, cookie);
+ next = pick_next_task(rq, prev, &rf);
clear_tsk_need_resched(prev);
clear_preempt_need_resched();
- rq->clock_skip_update = 0;
if (likely(prev != next)) {
rq->nr_switches++;
++*switch_count;
trace_sched_switch(preempt, prev, next);
- rq = context_switch(rq, prev, next, cookie); /* unlocks the rq */
+
+ /* Also unlocks the rq: */
+ rq = context_switch(rq, prev, next, &rf);
} else {
- lockdep_unpin_lock(&rq->lock, cookie);
+ rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
+ rq_unpin_lock(rq, &rf);
raw_spin_unlock_irq(&rq->lock);
}
smp_mb();
raw_spin_unlock_wait(¤t->pi_lock);
- /* causes final put_task_struct in finish_task_switch(). */
+ /* Causes final put_task_struct in finish_task_switch(): */
__set_current_state(TASK_DEAD);
- current->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
+
+ /* Tell freezer to ignore us: */
+ current->flags |= PF_NOFREEZE;
+
__schedule(false);
BUG();
- /* Avoid "noreturn function does return". */
+
+ /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
for (;;)
- cpu_relax(); /* For when BUG is null */
+ cpu_relax();
}
static inline void sched_submit_work(struct task_struct *tsk)
BUG_ON(prio > MAX_PRIO);
rq = __task_rq_lock(p, &rf);
+ update_rq_clock(rq);
/*
* Idle task boosting is a nono in general. There is one
check_class_changed(rq, p, prev_class, oldprio);
out_unlock:
- preempt_disable(); /* avoid rq from going away on us */
+ /* Avoid rq from going away on us: */
+ preempt_disable();
__task_rq_unlock(rq, &rf);
balance_callback(rq);
* the task might be in the middle of scheduling on another CPU.
*/
rq = task_rq_lock(p, &rf);
+ update_rq_clock(rq);
+
/*
* The RT priorities are set via sched_setscheduler(), but we still
* allow the 'normal' nice value to be set - but as expected
*/
int can_nice(const struct task_struct *p, const int nice)
{
- /* convert nice value [19,-20] to rlimit style value [1,40] */
+ /* 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) ||
}
/**
- * idle_cpu - is a given cpu idle currently?
+ * idle_cpu - is a given CPU idle currently?
* @cpu: the processor in question.
*
* Return: 1 if the CPU is currently idle. 0 otherwise.
}
/**
- * idle_task - return the idle task for a given cpu.
+ * idle_task - return the idle task for a given CPU.
* @cpu: the processor in question.
*
- * Return: The idle task for the cpu @cpu.
+ * Return: The idle task for the CPU @cpu.
*/
struct task_struct *idle_task(int cpu)
{
}
/*
- * check the target process has a UID that matches the current process's
+ * Check the target process has a UID that matches the current process's:
*/
static bool check_same_owner(struct task_struct *p)
{
return match;
}
-static bool dl_param_changed(struct task_struct *p,
- const struct sched_attr *attr)
+static bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
{
struct sched_dl_entity *dl_se = &p->dl;
int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
struct rq *rq;
- /* may grab non-irq protected spin_locks */
+ /* May grab non-irq protected spin_locks: */
BUG_ON(in_interrupt());
recheck:
- /* double check policy once rq lock held */
+ /* Double check policy once rq lock held: */
if (policy < 0) {
reset_on_fork = p->sched_reset_on_fork;
policy = oldpolicy = p->policy;
unsigned long rlim_rtprio =
task_rlimit(p, RLIMIT_RTPRIO);
- /* can't set/change the rt policy */
+ /* Can't set/change the rt policy: */
if (policy != p->policy && !rlim_rtprio)
return -EPERM;
- /* can't increase priority */
+ /* Can't increase priority: */
if (attr->sched_priority > p->rt_priority &&
attr->sched_priority > rlim_rtprio)
return -EPERM;
return -EPERM;
}
- /* can't change other user's priorities */
+ /* 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 */
+ /* Normal users shall not reset the sched_reset_on_fork flag: */
if (p->sched_reset_on_fork && !reset_on_fork)
return -EPERM;
}
}
/*
- * make sure no PI-waiters arrive (or leave) while we are
+ * 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, &rf);
+ update_rq_clock(rq);
/*
- * Changing the policy of the stop threads its a very bad idea
+ * Changing the policy of the stop threads its a very bad idea:
*/
if (p == rq->stop) {
task_rq_unlock(rq, p, &rf);
#endif
}
- /* recheck policy now with rq lock held */
+ /* Re-check policy now with rq lock held: */
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
policy = oldpolicy = -1;
task_rq_unlock(rq, p, &rf);
set_curr_task(rq, p);
check_class_changed(rq, p, prev_class, oldprio);
- preempt_disable(); /* avoid rq from going away on us */
+
+ /* Avoid rq from going away on us: */
+ preempt_disable();
task_rq_unlock(rq, p, &rf);
if (pi)
rt_mutex_adjust_pi(p);
- /*
- * Run balance callbacks after we've adjusted the PI chain.
- */
+ /* Run balance callbacks after we've adjusted the PI chain: */
balance_callback(rq);
preempt_enable();
/*
* Mimics kernel/events/core.c perf_copy_attr().
*/
-static int sched_copy_attr(struct sched_attr __user *uattr,
- struct sched_attr *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.
- */
+ /* 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 */
+ /* Bail out on silly large: */
+ if (size > PAGE_SIZE)
goto err_size;
- if (!size) /* abi compat */
+ /* ABI compatibility quirk: */
+ if (!size)
size = SCHED_ATTR_SIZE_VER0;
if (size < SCHED_ATTR_SIZE_VER0)
return -EFAULT;
/*
- * XXX: do we want to be lenient like existing syscalls; or do we want
+ * 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 on success. An error code otherwise.
*/
-SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
- struct sched_param __user *, param)
+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;
}
/**
- * sys_sched_setaffinity - set the cpu affinity of a process
+ * 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
+ * @user_mask_ptr: user-space pointer to the new CPU mask
*
* Return: 0 on success. An error code otherwise.
*/
}
/**
- * sys_sched_getaffinity - get the cpu affinity of a process
+ * 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
+ * @user_mask_ptr: user-space pointer to hold the current CPU mask
*
* Return: size of CPU mask copied to user_mask_ptr on success. An
* error code otherwise.
* Typical broken usage is:
*
* while (!event)
- * yield();
+ * 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
}
EXPORT_SYMBOL_GPL(yield_to);
+int io_schedule_prepare(void)
+{
+ int old_iowait = current->in_iowait;
+
+ current->in_iowait = 1;
+ blk_schedule_flush_plug(current);
+
+ return old_iowait;
+}
+
+void io_schedule_finish(int token)
+{
+ current->in_iowait = token;
+}
+
/*
* 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;
+ int token;
long ret;
- current->in_iowait = 1;
- blk_schedule_flush_plug(current);
-
- delayacct_blkio_start();
- rq = raw_rq();
- atomic_inc(&rq->nr_iowait);
+ token = io_schedule_prepare();
ret = schedule_timeout(timeout);
- current->in_iowait = old_iowait;
- atomic_dec(&rq->nr_iowait);
- delayacct_blkio_end();
+ io_schedule_finish(token);
return ret;
}
EXPORT_SYMBOL(io_schedule_timeout);
+void io_schedule(void)
+{
+ int token;
+
+ token = io_schedule_prepare();
+ schedule();
+ io_schedule_finish(token);
+}
+EXPORT_SYMBOL(io_schedule);
+
/**
* sys_sched_get_priority_max - return maximum RT priority.
* @policy: scheduling class.
/**
* init_idle - set up an idle thread for a given CPU
* @idle: task in question
- * @cpu: cpu the idle task belongs to
+ * @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.
#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
+ * 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
/*
* Kthreads which disallow setaffinity shouldn't be moved
- * to a new cpuset; we don't want to change their cpu
+ * 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
#ifdef CONFIG_SMP
-static bool sched_smp_initialized __read_mostly;
+bool sched_smp_initialized __read_mostly;
#ifdef CONFIG_NUMA_BALANCING
/* Migrate current task p to target_cpu */
#ifdef CONFIG_HOTPLUG_CPU
/*
- * Ensures that the idle task is using init_mm right before its cpu goes
+ * Ensure that the idle task is using init_mm right before its CPU goes
* offline.
*/
void idle_task_exit(void)
{
struct rq *rq = dead_rq;
struct task_struct *next, *stop = rq->stop;
- struct pin_cookie cookie;
+ struct rq_flags rf, old_rf;
int dest_cpu;
/*
for (;;) {
/*
* There's this thread running, bail when that's the only
- * remaining thread.
+ * remaining thread:
*/
if (rq->nr_running == 1)
break;
/*
- * pick_next_task assumes pinned rq->lock.
+ * pick_next_task() assumes pinned rq->lock:
*/
- cookie = lockdep_pin_lock(&rq->lock);
- next = pick_next_task(rq, &fake_task, cookie);
+ rq_pin_lock(rq, &rf);
+ next = pick_next_task(rq, &fake_task, &rf);
BUG_ON(!next);
next->sched_class->put_prev_task(rq, next);
* because !cpu_active at this point, which means load-balance
* will not interfere. Also, stop-machine.
*/
- lockdep_unpin_lock(&rq->lock, cookie);
+ rq_unpin_lock(rq, &rf);
raw_spin_unlock(&rq->lock);
raw_spin_lock(&next->pi_lock);
raw_spin_lock(&rq->lock);
continue;
}
+ /*
+ * __migrate_task() may return with a different
+ * rq->lock held and a new cookie in 'rf', but we need
+ * to preserve rf::clock_update_flags for 'dead_rq'.
+ */
+ old_rf = rf;
+
/* Find suitable destination for @next, with force if needed. */
dest_cpu = select_fallback_rq(dead_rq->cpu, next);
raw_spin_unlock(&rq->lock);
rq = dead_rq;
raw_spin_lock(&rq->lock);
+ rf = old_rf;
}
raw_spin_unlock(&next->pi_lock);
}
}
#endif /* CONFIG_HOTPLUG_CPU */
-static void set_rq_online(struct rq *rq)
+void set_rq_online(struct rq *rq)
{
if (!rq->online) {
const struct sched_class *class;
}
}
-static void set_rq_offline(struct rq *rq)
+void set_rq_offline(struct rq *rq)
{
if (rq->online) {
const struct sched_class *class;
rq->age_stamp = sched_clock_cpu(cpu);
}
-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);
+/*
+ * used to mark begin/end of suspend/resume:
+ */
+static int num_cpus_frozen;
-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 = %lu)",
- 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_debug_enabled 0
-# 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_ASYM_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_ASYM_CPUCAPACITY |
- 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 destroy_sched_domain(struct sched_domain *sd)
-{
- /*
- * 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);
- }
- if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
- kfree(sd->shared);
- kfree(sd);
-}
-
-static void destroy_sched_domains_rcu(struct rcu_head *rcu)
-{
- struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
-
- while (sd) {
- struct sched_domain *parent = sd->parent;
- destroy_sched_domain(sd);
- sd = parent;
- }
-}
-
-static void destroy_sched_domains(struct sched_domain *sd)
-{
- if (sd)
- call_rcu(&sd->rcu, destroy_sched_domains_rcu);
-}
-
-/*
- * 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_shared *, sd_llc_shared);
-DEFINE_PER_CPU(struct sched_domain *, sd_numa);
-DEFINE_PER_CPU(struct sched_domain *, sd_asym);
-
-static void update_top_cache_domain(int cpu)
-{
- struct sched_domain_shared *sds = NULL;
- struct sched_domain *sd;
- 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));
- sds = sd->shared;
- }
-
- rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
- per_cpu(sd_llc_size, cpu) = size;
- per_cpu(sd_llc_id, cpu) = id;
- rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
-
- 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);
- } else
- tmp = tmp->parent;
- }
-
- if (sd && sd_degenerate(sd)) {
- tmp = sd;
- sd = sd->parent;
- destroy_sched_domain(tmp);
- 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);
-
- 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);
- sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
-
- /*
- * 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 {
- int cpu, max_cpu = -1;
-
- sg->group_weight = cpumask_weight(sched_group_cpus(sg));
-
- if (!(sd->flags & SD_ASYM_PACKING))
- goto next;
-
- for_each_cpu(cpu, sched_group_cpus(sg)) {
- if (max_cpu < 0)
- max_cpu = cpu;
- else if (sched_asym_prefer(cpu, max_cpu))
- max_cpu = cpu;
- }
- sg->asym_prefer_cpu = max_cpu;
-
-next:
- sg = sg->next;
- } while (sg != sd->groups);
-
- if (cpu != group_balance_cpu(sg))
- return;
-
- update_group_capacity(sd, cpu);
-}
-
-/*
- * 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->sds, cpu))->ref))
- *per_cpu_ptr(sdd->sds, 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.
- *
- * These flags are purely descriptive of the topology and do not prescribe
- * behaviour. Behaviour is artificial and mapped in the below sd_init()
- * function:
- *
- * 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
- * SD_ASYM_CPUCAPACITY - describes mixed capacity topologies
- *
- * Odd one out, which beside describing the topology has a quirk also
- * prescribes the desired behaviour that goes along with it:
- *
- * SD_ASYM_PACKING - describes SMT quirks
- */
-#define TOPOLOGY_SD_FLAGS \
- (SD_SHARE_CPUCAPACITY | \
- SD_SHARE_PKG_RESOURCES | \
- SD_NUMA | \
- SD_ASYM_PACKING | \
- SD_ASYM_CPUCAPACITY | \
- SD_SHARE_POWERDOMAIN)
-
-static struct sched_domain *
-sd_init(struct sched_domain_topology_level *tl,
- const struct cpumask *cpu_map,
- struct sched_domain *child, int cpu)
-{
- struct sd_data *sdd = &tl->data;
- struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
- int sd_id, 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,
- .child = child,
-#ifdef CONFIG_SCHED_DEBUG
- .name = tl->name,
-#endif
- };
-
- cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
- sd_id = cpumask_first(sched_domain_span(sd));
-
- /*
- * Convert topological properties into behaviour.
- */
-
- if (sd->flags & SD_ASYM_CPUCAPACITY) {
- struct sched_domain *t = sd;
-
- for_each_lower_domain(t)
- t->flags |= SD_BALANCE_WAKE;
- }
-
- 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;
- }
-
- /*
- * For all levels sharing cache; connect a sched_domain_shared
- * instance.
- */
- if (sd->flags & SD_SHARE_PKG_RESOURCES) {
- sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
- atomic_inc(&sd->shared->ref);
- atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
- }
-
- sd->private = sdd;
-
- 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)
-{
- if (WARN_ON_ONCE(sched_smp_initialized))
- return;
-
- 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(unsigned int cpu)
-{
- int node = cpu_to_node(cpu);
- int i, j;
-
- 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(unsigned 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]);
- }
-}
-
-#else
-static inline void sched_init_numa(void) { }
-static void sched_domains_numa_masks_set(unsigned int cpu) { }
-static void sched_domains_numa_masks_clear(unsigned int cpu) { }
-#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->sds = alloc_percpu(struct sched_domain_shared *);
- if (!sdd->sds)
- 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_domain_shared *sds;
- 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;
-
- sds = kzalloc_node(sizeof(struct sched_domain_shared),
- GFP_KERNEL, cpu_to_node(j));
- if (!sds)
- return -ENOMEM;
-
- *per_cpu_ptr(sdd->sds, j) = sds;
-
- 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->sds)
- kfree(*per_cpu_ptr(sdd->sds, 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->sds);
- sdd->sds = 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_map, child, cpu);
-
- if (child) {
- sd->level = child->level + 1;
- sched_domain_level_max = max(sched_domain_level_max, sd->level);
- child->parent = sd;
-
- 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;
- struct rq *rq = NULL;
- 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) {
- rq = cpu_rq(i);
- sd = *per_cpu_ptr(d.sd, i);
-
- /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
- if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
- WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
-
- cpu_attach_domain(sd, d.rd, i);
- }
- rcu_read_unlock();
-
- if (rq && sched_debug_enabled) {
- pr_info("span: %*pbl (max cpu_capacity = %lu)\n",
- cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
- }
-
- 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 void cpuset_cpu_active(void)
+/*
+ * 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 void cpuset_cpu_active(void)
{
if (cpuhp_tasks_frozen) {
/*
* Put the rq online, if not already. This happens:
*
* 1) In the early boot process, because we build the real domains
- * after all cpus have been brought up.
+ * after all CPUs have been brought up.
*
* 2) At runtime, if cpuset_cpu_active() fails to rebuild the
* domains.
/*
* 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
+ * CPU masks are stable and all blatant races in the below code cannot
* happen.
*/
mutex_lock(&sched_domains_mutex);
init_sched_dl_class();
sched_init_smt();
+ sched_clock_init_late();
sched_smp_initialized = true;
}
void __init sched_init_smp(void)
{
sched_init_granularity();
+ sched_clock_init_late();
}
#endif /* CONFIG_SMP */
int i, j;
unsigned long alloc_size = 0, ptr;
+ sched_clock_init();
+
for (i = 0; i < WAIT_TABLE_SIZE; i++)
init_waitqueue_head(bit_wait_table + 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());
+ 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();
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
/*
- * How much cpu bandwidth does root_task_group get?
+ * 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
+ * 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:
+ * then A0's share of the CPU resource is:
*
* A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
*
void ___might_sleep(const char *file, int line, int preempt_offset)
{
- static unsigned long prev_jiffy; /* ratelimiting */
+ /* Ratelimiting timestamp: */
+ static unsigned long prev_jiffy;
+
unsigned long preempt_disable_ip;
- rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
+ /* WARN_ON_ONCE() by default, no rate limit required: */
+ rcu_sleep_check();
+
if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
!is_idle_task(current)) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;
prev_jiffy = jiffies;
- /* Save this before calling printk(), since that will clobber it */
+ /* Save this before calling printk(), since that will clobber it: */
preempt_disable_ip = get_preempt_disable_ip(current);
printk(KERN_ERR
*/
/**
- * curr_task - return the current task for a given cpu.
+ * curr_task - return the current task for a given CPU.
* @cpu: the processor in question.
*
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
#ifdef CONFIG_IA64
/**
- * set_curr_task - set the current task for a given cpu.
+ * 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
+ * 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
spin_lock_irqsave(&task_group_lock, flags);
list_add_rcu(&tg->list, &task_groups);
- WARN_ON(!parent); /* root should already exist */
+ /* Root should already exist: */
+ WARN_ON(!parent);
tg->parent = parent;
INIT_LIST_HEAD(&tg->children);
/* rcu callback to free various structures associated with a task group */
static void sched_free_group_rcu(struct rcu_head *rhp)
{
- /* now it should be safe to free those cfs_rqs */
+ /* Now it should be safe to free those cfs_rqs: */
sched_free_group(container_of(rhp, struct task_group, rcu));
}
void sched_destroy_group(struct task_group *tg)
{
- /* wait for possible concurrent references to cfs_rqs complete */
+ /* Wait for possible concurrent references to cfs_rqs complete: */
call_rcu(&tg->rcu, sched_free_group_rcu);
}
{
unsigned long flags;
- /* end participation in shares distribution */
+ /* End participation in shares distribution: */
unregister_fair_sched_group(tg);
spin_lock_irqsave(&task_group_lock, flags);
struct rq *rq;
rq = task_rq_lock(tsk, &rf);
+ update_rq_clock(rq);
running = task_current(rq, tsk);
queued = task_on_rq_queued(tsk);
if (queued)
dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
- if (unlikely(running))
+ if (running)
put_prev_task(rq, tsk);
sched_change_group(tsk, TASK_MOVE_GROUP);
if (queued)
enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
- if (unlikely(running))
+ if (running)
set_curr_task(rq, tsk);
task_rq_unlock(rq, tsk, &rf);
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 */
+ /*
+ * Make sure that internally we keep jiffies.
+ * Also, writing zero resets the timeslice to default:
+ */
if (!ret && write) {
- sched_rr_timeslice = sched_rr_timeslice <= 0 ?
- RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
+ sched_rr_timeslice =
+ sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
+ msecs_to_jiffies(sysctl_sched_rr_timeslice);
}
mutex_unlock(&mutex);
return ret;
rq = task_rq_lock(task, &rf);
+ update_rq_clock(rq);
sched_change_group(task, TASK_SET_GROUP);
task_rq_unlock(rq, task, &rf);
cfs_b->quota = quota;
__refill_cfs_bandwidth_runtime(cfs_b);
- /* restart the period timer (if active) to handle new period expiry */
+
+ /* 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) {
parent_quota = parent_b->hierarchical_quota;
/*
- * ensure max(child_quota) <= parent_quota, inherit when no
- * limit is set
+ * Ensure max(child_quota) <= parent_quota, inherit when no
+ * limit is set:
*/
if (quota == RUNTIME_INF)
quota = parent_quota;
.write_u64 = cpu_rt_period_write_uint,
},
#endif
- { } /* terminate */
+ { } /* Terminate */
};
struct cgroup_subsys cpu_cgrp_subsys = {
git.samba.org / sfrench / cifs-2.6.git / blobdiff