* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
llist: Add back llist_add_batch() and llist_del_first() prototypes
sched: Don't use tasklist_lock for debug prints
sched: Warn on rt throttling
sched: Unify the ->cpus_allowed mask copy
sched: Wrap scheduler p->cpus_allowed access
sched: Request for idle balance during nohz idle load balance
sched: Use resched IPI to kick off the nohz idle balance
sched: Fix idle_cpu()
llist: Remove cpu_relax() usage in cmpxchg loops
sched: Convert to struct llist
llist: Add llist_next()
irq_work: Use llist in the struct irq_work logic
llist: Return whether list is empty before adding in llist_add()
llist: Move cpu_relax() to after the cmpxchg()
llist: Remove the platform-dependent NMI checks
llist: Make some llist functions inline
sched, tracing: Show PREEMPT_ACTIVE state in trace_sched_switch
sched: Remove redundant test in check_preempt_tick()
sched: Add documentation for bandwidth control
sched: Return unused runtime on group dequeue
...
--- /dev/null
+CFS Bandwidth Control
+=====================
+
+[ This document only discusses CPU bandwidth control for SCHED_NORMAL.
+ The SCHED_RT case is covered in Documentation/scheduler/sched-rt-group.txt ]
+
+CFS bandwidth control is a CONFIG_FAIR_GROUP_SCHED extension which allows the
+specification of the maximum CPU bandwidth available to a group or hierarchy.
+
+The bandwidth allowed for a group is specified using a quota and period. Within
+each given "period" (microseconds), a group is allowed to consume only up to
+"quota" microseconds of CPU time. When the CPU bandwidth consumption of a
+group exceeds this limit (for that period), the tasks belonging to its
+hierarchy will be throttled and are not allowed to run again until the next
+period.
+
+A group's unused runtime is globally tracked, being refreshed with quota units
+above at each period boundary. As threads consume this bandwidth it is
+transferred to cpu-local "silos" on a demand basis. The amount transferred
+within each of these updates is tunable and described as the "slice".
+
+Management
+----------
+Quota and period are managed within the cpu subsystem via cgroupfs.
+
+cpu.cfs_quota_us: the total available run-time within a period (in microseconds)
+cpu.cfs_period_us: the length of a period (in microseconds)
+cpu.stat: exports throttling statistics [explained further below]
+
+The default values are:
+ cpu.cfs_period_us=100ms
+ cpu.cfs_quota=-1
+
+A value of -1 for cpu.cfs_quota_us indicates that the group does not have any
+bandwidth restriction in place, such a group is described as an unconstrained
+bandwidth group. This represents the traditional work-conserving behavior for
+CFS.
+
+Writing any (valid) positive value(s) will enact the specified bandwidth limit.
+The minimum quota allowed for the quota or period is 1ms. There is also an
+upper bound on the period length of 1s. Additional restrictions exist when
+bandwidth limits are used in a hierarchical fashion, these are explained in
+more detail below.
+
+Writing any negative value to cpu.cfs_quota_us will remove the bandwidth limit
+and return the group to an unconstrained state once more.
+
+Any updates to a group's bandwidth specification will result in it becoming
+unthrottled if it is in a constrained state.
+
+System wide settings
+--------------------
+For efficiency run-time is transferred between the global pool and CPU local
+"silos" in a batch fashion. This greatly reduces global accounting pressure
+on large systems. The amount transferred each time such an update is required
+is described as the "slice".
+
+This is tunable via procfs:
+ /proc/sys/kernel/sched_cfs_bandwidth_slice_us (default=5ms)
+
+Larger slice values will reduce transfer overheads, while smaller values allow
+for more fine-grained consumption.
+
+Statistics
+----------
+A group's bandwidth statistics are exported via 3 fields in cpu.stat.
+
+cpu.stat:
+- nr_periods: Number of enforcement intervals that have elapsed.
+- nr_throttled: Number of times the group has been throttled/limited.
+- throttled_time: The total time duration (in nanoseconds) for which entities
+ of the group have been throttled.
+
+This interface is read-only.
+
+Hierarchical considerations
+---------------------------
+The interface enforces that an individual entity's bandwidth is always
+attainable, that is: max(c_i) <= C. However, over-subscription in the
+aggregate case is explicitly allowed to enable work-conserving semantics
+within a hierarchy.
+ e.g. \Sum (c_i) may exceed C
+[ Where C is the parent's bandwidth, and c_i its children ]
+
+
+There are two ways in which a group may become throttled:
+ a. it fully consumes its own quota within a period
+ b. a parent's quota is fully consumed within its period
+
+In case b) above, even though the child may have runtime remaining it will not
+be allowed to until the parent's runtime is refreshed.
+
+Examples
+--------
+1. Limit a group to 1 CPU worth of runtime.
+
+ If period is 250ms and quota is also 250ms, the group will get
+ 1 CPU worth of runtime every 250ms.
+
+ # echo 250000 > cpu.cfs_quota_us /* quota = 250ms */
+ # echo 250000 > cpu.cfs_period_us /* period = 250ms */
+
+2. Limit a group to 2 CPUs worth of runtime on a multi-CPU machine.
+
+ With 500ms period and 1000ms quota, the group can get 2 CPUs worth of
+ runtime every 500ms.
+
+ # echo 1000000 > cpu.cfs_quota_us /* quota = 1000ms */
+ # echo 500000 > cpu.cfs_period_us /* period = 500ms */
+
+ The larger period here allows for increased burst capacity.
+
+3. Limit a group to 20% of 1 CPU.
+
+ With 50ms period, 10ms quota will be equivalent to 20% of 1 CPU.
+
+ # echo 10000 > cpu.cfs_quota_us /* quota = 10ms */
+ # echo 50000 > cpu.cfs_period_us /* period = 50ms */
+
+ By using a small period here we are ensuring a consistent latency
+ response at the expense of burst capacity.
+
depends on ACPI_APEI && X86
select ACPI_HED
select IRQ_WORK
- select LLIST
select GENERIC_ALLOCATOR
help
Generic Hardware Error Source provides a way to report
#ifndef _LINUX_IRQ_WORK_H
#define _LINUX_IRQ_WORK_H
+#include <linux/llist.h>
+
struct irq_work {
- struct irq_work *next;
+ unsigned long flags;
+ struct llist_node llnode;
void (*func)(struct irq_work *);
};
static inline
-void init_irq_work(struct irq_work *entry, void (*func)(struct irq_work *))
+void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *))
{
- entry->next = NULL;
- entry->func = func;
+ work->flags = 0;
+ work->func = func;
}
-bool irq_work_queue(struct irq_work *entry);
+bool irq_work_queue(struct irq_work *work);
void irq_work_run(void);
-void irq_work_sync(struct irq_work *entry);
+void irq_work_sync(struct irq_work *work);
#endif /* _LINUX_IRQ_WORK_H */
*
* The basic atomic operation of this list is cmpxchg on long. On
* architectures that don't have NMI-safe cmpxchg implementation, the
- * list can NOT be used in NMI handler. So code uses the list in NMI
- * handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
+ * list can NOT be used in NMI handlers. So code that uses the list in
+ * an NMI handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
+ *
+ * Copyright 2010,2011 Intel Corp.
+ * Author: Huang Ying <ying.huang@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/processor.h>
+
struct llist_head {
struct llist_node *first;
};
* test whether the list is empty without deleting something from the
* list.
*/
-static inline int llist_empty(const struct llist_head *head)
+static inline bool llist_empty(const struct llist_head *head)
{
return ACCESS_ONCE(head->first) == NULL;
}
-void llist_add(struct llist_node *new, struct llist_head *head);
-void llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
- struct llist_head *head);
-struct llist_node *llist_del_first(struct llist_head *head);
-struct llist_node *llist_del_all(struct llist_head *head);
+static inline struct llist_node *llist_next(struct llist_node *node)
+{
+ return node->next;
+}
+
+/**
+ * llist_add - add a new entry
+ * @new: new entry to be added
+ * @head: the head for your lock-less list
+ *
+ * Return whether list is empty before adding.
+ */
+static inline bool llist_add(struct llist_node *new, struct llist_head *head)
+{
+ struct llist_node *entry, *old_entry;
+
+ entry = head->first;
+ for (;;) {
+ old_entry = entry;
+ new->next = entry;
+ entry = cmpxchg(&head->first, old_entry, new);
+ if (entry == old_entry)
+ break;
+ }
+
+ return old_entry == NULL;
+}
+
+/**
+ * llist_del_all - delete all entries from lock-less list
+ * @head: the head of lock-less list to delete all entries
+ *
+ * If list is empty, return NULL, otherwise, delete all entries and
+ * return the pointer to the first entry. The order of entries
+ * deleted is from the newest to the oldest added one.
+ */
+static inline struct llist_node *llist_del_all(struct llist_head *head)
+{
+ return xchg(&head->first, NULL);
+}
+
+extern bool llist_add_batch(struct llist_node *new_first,
+ struct llist_node *new_last,
+ struct llist_head *head);
+extern struct llist_node *llist_del_first(struct llist_head *head);
+
#endif /* LLIST_H */
#include <linux/task_io_accounting.h>
#include <linux/latencytop.h>
#include <linux/cred.h>
+#include <linux/llist.h>
#include <asm/processor.h>
unsigned int ptrace;
#ifdef CONFIG_SMP
- struct task_struct *wake_entry;
+ struct llist_node wake_entry;
int on_cpu;
#endif
int on_rq;
static inline void sched_autogroup_exit(struct signal_struct *sig) { }
#endif
+#ifdef CONFIG_CFS_BANDWIDTH
+extern unsigned int sysctl_sched_cfs_bandwidth_slice;
+#endif
+
#ifdef CONFIG_RT_MUTEXES
extern int rt_mutex_getprio(struct task_struct *p);
extern void rt_mutex_setprio(struct task_struct *p, int prio);
* For all intents and purposes a preempted task is a running task.
*/
if (task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)
- state = TASK_RUNNING;
+ state = TASK_RUNNING | TASK_STATE_MAX;
#endif
return state;
__entry->next_prio = next->prio;
),
- TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s ==> next_comm=%s next_pid=%d next_prio=%d",
+ TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s%s ==> next_comm=%s next_pid=%d next_prio=%d",
__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
- __entry->prev_state ?
- __print_flags(__entry->prev_state, "|",
+ __entry->prev_state & (TASK_STATE_MAX-1) ?
+ __print_flags(__entry->prev_state & (TASK_STATE_MAX-1), "|",
{ 1, "S"} , { 2, "D" }, { 4, "T" }, { 8, "t" },
{ 16, "Z" }, { 32, "X" }, { 64, "x" },
{ 128, "W" }) : "R",
+ __entry->prev_state & TASK_STATE_MAX ? "+" : "",
__entry->next_comm, __entry->next_pid, __entry->next_prio)
);
depends on CGROUP_SCHED
default CGROUP_SCHED
+config CFS_BANDWIDTH
+ bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
+ depends on EXPERIMENTAL
+ depends on FAIR_GROUP_SCHED
+ default n
+ help
+ This option allows users to define CPU bandwidth rates (limits) for
+ tasks running within the fair group scheduler. Groups with no limit
+ set are considered to be unconstrained and will run with no
+ restriction.
+ See tip/Documentation/scheduler/sched-bwc.txt for more information.
+
config RT_GROUP_SCHED
bool "Group scheduling for SCHED_RR/FIFO"
depends on EXPERIMENTAL
* claimed NULL, 3 -> {pending} : claimed to be enqueued
* pending next, 3 -> {busy} : queued, pending callback
* busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed
- *
- * We use the lower two bits of the next pointer to keep PENDING and BUSY
- * flags.
*/
#define IRQ_WORK_PENDING 1UL
#define IRQ_WORK_BUSY 2UL
#define IRQ_WORK_FLAGS 3UL
-static inline bool irq_work_is_set(struct irq_work *entry, int flags)
-{
- return (unsigned long)entry->next & flags;
-}
-
-static inline struct irq_work *irq_work_next(struct irq_work *entry)
-{
- unsigned long next = (unsigned long)entry->next;
- next &= ~IRQ_WORK_FLAGS;
- return (struct irq_work *)next;
-}
-
-static inline struct irq_work *next_flags(struct irq_work *entry, int flags)
-{
- unsigned long next = (unsigned long)entry;
- next |= flags;
- return (struct irq_work *)next;
-}
-
-static DEFINE_PER_CPU(struct irq_work *, irq_work_list);
+static DEFINE_PER_CPU(struct llist_head, irq_work_list);
/*
* Claim the entry so that no one else will poke at it.
*/
-static bool irq_work_claim(struct irq_work *entry)
+static bool irq_work_claim(struct irq_work *work)
{
- struct irq_work *next, *nflags;
+ unsigned long flags, nflags;
- do {
- next = entry->next;
- if ((unsigned long)next & IRQ_WORK_PENDING)
+ for (;;) {
+ flags = work->flags;
+ if (flags & IRQ_WORK_PENDING)
return false;
- nflags = next_flags(next, IRQ_WORK_FLAGS);
- } while (cmpxchg(&entry->next, next, nflags) != next);
+ nflags = flags | IRQ_WORK_FLAGS;
+ if (cmpxchg(&work->flags, flags, nflags) == flags)
+ break;
+ cpu_relax();
+ }
return true;
}
-
void __weak arch_irq_work_raise(void)
{
/*
/*
* Queue the entry and raise the IPI if needed.
*/
-static void __irq_work_queue(struct irq_work *entry)
+static void __irq_work_queue(struct irq_work *work)
{
- struct irq_work *next;
+ bool empty;
preempt_disable();
- do {
- next = __this_cpu_read(irq_work_list);
- /* Can assign non-atomic because we keep the flags set. */
- entry->next = next_flags(next, IRQ_WORK_FLAGS);
- } while (this_cpu_cmpxchg(irq_work_list, next, entry) != next);
-
+ empty = llist_add(&work->llnode, &__get_cpu_var(irq_work_list));
/* The list was empty, raise self-interrupt to start processing. */
- if (!irq_work_next(entry))
+ if (empty)
arch_irq_work_raise();
preempt_enable();
*
* Can be re-enqueued while the callback is still in progress.
*/
-bool irq_work_queue(struct irq_work *entry)
+bool irq_work_queue(struct irq_work *work)
{
- if (!irq_work_claim(entry)) {
+ if (!irq_work_claim(work)) {
/*
* Already enqueued, can't do!
*/
return false;
}
- __irq_work_queue(entry);
+ __irq_work_queue(work);
return true;
}
EXPORT_SYMBOL_GPL(irq_work_queue);
*/
void irq_work_run(void)
{
- struct irq_work *list;
+ struct irq_work *work;
+ struct llist_head *this_list;
+ struct llist_node *llnode;
- if (this_cpu_read(irq_work_list) == NULL)
+ this_list = &__get_cpu_var(irq_work_list);
+ if (llist_empty(this_list))
return;
BUG_ON(!in_irq());
BUG_ON(!irqs_disabled());
- list = this_cpu_xchg(irq_work_list, NULL);
-
- while (list != NULL) {
- struct irq_work *entry = list;
+ llnode = llist_del_all(this_list);
+ while (llnode != NULL) {
+ work = llist_entry(llnode, struct irq_work, llnode);
- list = irq_work_next(list);
+ llnode = llist_next(llnode);
/*
- * Clear the PENDING bit, after this point the @entry
+ * Clear the PENDING bit, after this point the @work
* can be re-used.
*/
- entry->next = next_flags(NULL, IRQ_WORK_BUSY);
- entry->func(entry);
+ work->flags = IRQ_WORK_BUSY;
+ work->func(work);
/*
* Clear the BUSY bit and return to the free state if
* no-one else claimed it meanwhile.
*/
- (void)cmpxchg(&entry->next,
- next_flags(NULL, IRQ_WORK_BUSY),
- NULL);
+ (void)cmpxchg(&work->flags, IRQ_WORK_BUSY, 0);
}
}
EXPORT_SYMBOL_GPL(irq_work_run);
* Synchronize against the irq_work @entry, ensures the entry is not
* currently in use.
*/
-void irq_work_sync(struct irq_work *entry)
+void irq_work_sync(struct irq_work *work)
{
WARN_ON_ONCE(irqs_disabled());
- while (irq_work_is_set(entry, IRQ_WORK_BUSY))
+ while (work->flags & IRQ_WORK_BUSY)
cpu_relax();
}
EXPORT_SYMBOL_GPL(irq_work_sync);
return sysctl_sched_rt_runtime >= 0;
}
-static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
+static void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
{
- ktime_t now;
+ unsigned long delta;
+ ktime_t soft, hard, now;
+
+ for (;;) {
+ if (hrtimer_active(period_timer))
+ break;
+
+ now = hrtimer_cb_get_time(period_timer);
+ hrtimer_forward(period_timer, now, period);
+ soft = hrtimer_get_softexpires(period_timer);
+ hard = hrtimer_get_expires(period_timer);
+ delta = ktime_to_ns(ktime_sub(hard, soft));
+ __hrtimer_start_range_ns(period_timer, soft, delta,
+ HRTIMER_MODE_ABS_PINNED, 0);
+ }
+}
+
+static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
+{
if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return;
return;
raw_spin_lock(&rt_b->rt_runtime_lock);
- for (;;) {
- unsigned long delta;
- ktime_t soft, hard;
-
- if (hrtimer_active(&rt_b->rt_period_timer))
- break;
-
- now = hrtimer_cb_get_time(&rt_b->rt_period_timer);
- hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period);
-
- soft = hrtimer_get_softexpires(&rt_b->rt_period_timer);
- hard = hrtimer_get_expires(&rt_b->rt_period_timer);
- delta = ktime_to_ns(ktime_sub(hard, soft));
- __hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta,
- HRTIMER_MODE_ABS_PINNED, 0);
- }
+ start_bandwidth_timer(&rt_b->rt_period_timer, rt_b->rt_period);
raw_spin_unlock(&rt_b->rt_runtime_lock);
}
static LIST_HEAD(task_groups);
+struct cfs_bandwidth {
+#ifdef CONFIG_CFS_BANDWIDTH
+ raw_spinlock_t lock;
+ ktime_t period;
+ u64 quota, runtime;
+ s64 hierarchal_quota;
+ u64 runtime_expires;
+
+ int idle, timer_active;
+ struct hrtimer period_timer, slack_timer;
+ struct list_head throttled_cfs_rq;
+
+ /* statistics */
+ int nr_periods, nr_throttled;
+ u64 throttled_time;
+#endif
+};
+
/* task group related information */
struct task_group {
struct cgroup_subsys_state css;
#ifdef CONFIG_SCHED_AUTOGROUP
struct autogroup *autogroup;
#endif
+
+ struct cfs_bandwidth cfs_bandwidth;
};
/* task_group_lock serializes the addition/removal of task groups */
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
- unsigned long nr_running;
+ unsigned long nr_running, h_nr_running;
u64 exec_clock;
u64 min_vruntime;
unsigned long load_contribution;
#endif
+#ifdef CONFIG_CFS_BANDWIDTH
+ int runtime_enabled;
+ u64 runtime_expires;
+ s64 runtime_remaining;
+
+ u64 throttled_timestamp;
+ int throttled, throttle_count;
+ struct list_head throttled_list;
+#endif
#endif
};
+#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_CFS_BANDWIDTH
+static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
+{
+ return &tg->cfs_bandwidth;
+}
+
+static inline u64 default_cfs_period(void);
+static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
+static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
+
+static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
+{
+ struct cfs_bandwidth *cfs_b =
+ container_of(timer, struct cfs_bandwidth, slack_timer);
+ do_sched_cfs_slack_timer(cfs_b);
+
+ return HRTIMER_NORESTART;
+}
+
+static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
+{
+ struct cfs_bandwidth *cfs_b =
+ container_of(timer, struct cfs_bandwidth, period_timer);
+ ktime_t now;
+ int overrun;
+ int idle = 0;
+
+ for (;;) {
+ now = hrtimer_cb_get_time(timer);
+ overrun = hrtimer_forward(timer, now, cfs_b->period);
+
+ if (!overrun)
+ break;
+
+ idle = do_sched_cfs_period_timer(cfs_b, overrun);
+ }
+
+ return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
+}
+
+static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
+{
+ raw_spin_lock_init(&cfs_b->lock);
+ cfs_b->runtime = 0;
+ cfs_b->quota = RUNTIME_INF;
+ cfs_b->period = ns_to_ktime(default_cfs_period());
+
+ INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
+ hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ cfs_b->period_timer.function = sched_cfs_period_timer;
+ hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ cfs_b->slack_timer.function = sched_cfs_slack_timer;
+}
+
+static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ cfs_rq->runtime_enabled = 0;
+ INIT_LIST_HEAD(&cfs_rq->throttled_list);
+}
+
+/* requires cfs_b->lock, may release to reprogram timer */
+static void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
+{
+ /*
+ * The timer may be active because we're trying to set a new bandwidth
+ * period or because we're racing with the tear-down path
+ * (timer_active==0 becomes visible before the hrtimer call-back
+ * terminates). In either case we ensure that it's re-programmed
+ */
+ while (unlikely(hrtimer_active(&cfs_b->period_timer))) {
+ raw_spin_unlock(&cfs_b->lock);
+ /* ensure cfs_b->lock is available while we wait */
+ hrtimer_cancel(&cfs_b->period_timer);
+
+ raw_spin_lock(&cfs_b->lock);
+ /* if someone else restarted the timer then we're done */
+ if (cfs_b->timer_active)
+ return;
+ }
+
+ cfs_b->timer_active = 1;
+ start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
+}
+
+static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
+{
+ hrtimer_cancel(&cfs_b->period_timer);
+ hrtimer_cancel(&cfs_b->slack_timer);
+}
+#else
+static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
+static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
+static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
+
+static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
+{
+ return NULL;
+}
+#endif /* CONFIG_CFS_BANDWIDTH */
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
/* Real-Time classes' related field in a runqueue: */
struct rt_rq {
struct rt_prio_array active;
unsigned long cpu_power;
- unsigned char idle_at_tick;
+ unsigned char idle_balance;
/* For active balancing */
int post_schedule;
int active_balance;
int cpu;
int online;
- unsigned long avg_load_per_task;
-
u64 rt_avg;
u64 age_stamp;
u64 idle_stamp;
#endif
#ifdef CONFIG_SMP
- struct task_struct *wake_list;
+ struct llist_head wake_list;
#endif
};
smp_send_reschedule(cpu);
}
+static inline bool got_nohz_idle_kick(void)
+{
+ return idle_cpu(smp_processor_id()) && this_rq()->nohz_balance_kick;
+}
+
+#else /* CONFIG_NO_HZ */
+
+static inline bool got_nohz_idle_kick(void)
+{
+ return false;
+}
+
#endif /* CONFIG_NO_HZ */
static u64 sched_avg_period(void)
update_load_sub(&rq->load, load);
}
-#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
+#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
+ (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
typedef int (*tg_visitor)(struct task_group *, void *);
/*
- * Iterate the full tree, calling @down when first entering a node and @up when
- * leaving it for the final time.
+ * 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.
*/
-static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
+static int walk_tg_tree_from(struct task_group *from,
+ tg_visitor down, tg_visitor up, void *data)
{
struct task_group *parent, *child;
int ret;
- rcu_read_lock();
- parent = &root_task_group;
+ parent = from;
+
down:
ret = (*down)(parent, data);
if (ret)
- goto out_unlock;
+ goto out;
list_for_each_entry_rcu(child, &parent->children, siblings) {
parent = child;
goto down;
continue;
}
ret = (*up)(parent, data);
- if (ret)
- goto out_unlock;
+ if (ret || parent == from)
+ goto out;
child = parent;
parent = parent->parent;
if (parent)
goto up;
-out_unlock:
- rcu_read_unlock();
-
+out:
return ret;
}
+/*
+ * Iterate the full tree, calling @down when first entering a node and @up when
+ * leaving it for the final time.
+ *
+ * Caller must hold rcu_lock or sufficient equivalent.
+ */
+
+static inline int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
+{
+ return walk_tg_tree_from(&root_task_group, down, up, data);
+}
+
static int tg_nop(struct task_group *tg, void *data)
{
return 0;
unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
if (nr_running)
- rq->avg_load_per_task = rq->load.weight / nr_running;
- else
- rq->avg_load_per_task = 0;
+ return rq->load.weight / nr_running;
- return rq->avg_load_per_task;
+ return 0;
}
#ifdef CONFIG_PREEMPT
rq->nr_uninterruptible--;
enqueue_task(rq, p, flags);
- inc_nr_running(rq);
}
/*
rq->nr_uninterruptible++;
dequeue_task(rq, p, flags);
- dec_nr_running(rq);
}
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
/* Look for allowed, online CPU in same node. */
for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
- if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
+ if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
return dest_cpu;
/* Any allowed, online CPU? */
- dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
+ dest_cpu = cpumask_any_and(tsk_cpus_allowed(p), cpu_active_mask);
if (dest_cpu < nr_cpu_ids)
return dest_cpu;
* [ this allows ->select_task() to simply return task_cpu(p) and
* not worry about this generic constraint ]
*/
- if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
+ if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
!cpu_online(cpu)))
cpu = select_fallback_rq(task_cpu(p), p);
}
#ifdef CONFIG_SMP
-static void sched_ttwu_do_pending(struct task_struct *list)
+static void sched_ttwu_pending(void)
{
struct rq *rq = this_rq();
+ struct llist_node *llist = llist_del_all(&rq->wake_list);
+ struct task_struct *p;
raw_spin_lock(&rq->lock);
- while (list) {
- struct task_struct *p = list;
- list = list->wake_entry;
+ while (llist) {
+ p = llist_entry(llist, struct task_struct, wake_entry);
+ llist = llist_next(llist);
ttwu_do_activate(rq, p, 0);
}
raw_spin_unlock(&rq->lock);
}
-#ifdef CONFIG_HOTPLUG_CPU
-
-static void sched_ttwu_pending(void)
-{
- struct rq *rq = this_rq();
- struct task_struct *list = xchg(&rq->wake_list, NULL);
-
- if (!list)
- return;
-
- sched_ttwu_do_pending(list);
-}
-
-#endif /* CONFIG_HOTPLUG_CPU */
-
void scheduler_ipi(void)
{
- struct rq *rq = this_rq();
- struct task_struct *list = xchg(&rq->wake_list, NULL);
-
- if (!list)
+ if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
return;
/*
* somewhat pessimize the simple resched case.
*/
irq_enter();
- sched_ttwu_do_pending(list);
+ sched_ttwu_pending();
+
+ /*
+ * Check if someone kicked us for doing the nohz idle load balance.
+ */
+ if (unlikely(got_nohz_idle_kick() && !need_resched())) {
+ 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);
- struct task_struct *next = rq->wake_list;
-
- for (;;) {
- struct task_struct *old = next;
-
- p->wake_entry = next;
- next = cmpxchg(&rq->wake_list, old, p);
- if (next == old)
- break;
- }
-
- if (!next)
+ if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))
smp_send_reschedule(cpu);
}
*/
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 (p->policy == SCHED_FIFO || p->policy == SCHED_RR) {
+ if (task_has_rt_policy(p)) {
p->policy = SCHED_NORMAL;
- p->normal_prio = p->static_prio;
- }
-
- if (PRIO_TO_NICE(p->static_prio) < 0) {
p->static_prio = NICE_TO_PRIO(0);
- p->normal_prio = p->static_prio;
- set_load_weight(p);
- }
+ 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
p->sched_reset_on_fork = 0;
}
- /*
- * Make sure we do not leak PI boosting priority to the child.
- */
- p->prio = current->normal_prio;
-
if (!rt_prio(p->prio))
p->sched_class = &fair_sched_class;
perf_event_task_tick();
#ifdef CONFIG_SMP
- rq->idle_at_tick = idle_cpu(cpu);
+ rq->idle_balance = idle_cpu(cpu);
trigger_load_balance(rq, cpu);
#endif
}
* Optimization: we know that if all tasks are in
* the fair class we can call that function directly:
*/
- if (likely(rq->nr_running == rq->cfs.nr_running)) {
+ if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
p = fair_sched_class.pick_next_task(rq);
if (likely(p))
return p;
*/
int idle_cpu(int cpu)
{
- return cpu_curr(cpu) == cpu_rq(cpu)->idle;
+ 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;
}
/**
printk(KERN_INFO
" task PC stack pid father\n");
#endif
- read_lock(&tasklist_lock);
+ rcu_read_lock();
do_each_thread(g, p) {
/*
* reset the NMI-timeout, listing all files on a slow
#ifdef CONFIG_SCHED_DEBUG
sysrq_sched_debug_show();
#endif
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
/*
* Only show locks if all tasks are dumped:
*/
{
if (p->sched_class && p->sched_class->set_cpus_allowed)
p->sched_class->set_cpus_allowed(p, new_mask);
- else {
- cpumask_copy(&p->cpus_allowed, new_mask);
- p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
- }
+
+ cpumask_copy(&p->cpus_allowed, new_mask);
+ p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
}
/*
if (task_cpu(p) != src_cpu)
goto done;
/* Affinity changed (again). */
- if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
+ if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
goto fail;
/*
rq->calc_load_active = 0;
}
+#ifdef CONFIG_CFS_BANDWIDTH
+static void unthrottle_offline_cfs_rqs(struct rq *rq)
+{
+ struct cfs_rq *cfs_rq;
+
+ for_each_leaf_cfs_rq(rq, cfs_rq) {
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+
+ if (!cfs_rq->runtime_enabled)
+ continue;
+
+ /*
+ * clock_task is not advancing so we just need to make sure
+ * there's some valid quota amount
+ */
+ cfs_rq->runtime_remaining = cfs_b->quota;
+ if (cfs_rq_throttled(cfs_rq))
+ unthrottle_cfs_rq(cfs_rq);
+ }
+}
+#else
+static void unthrottle_offline_cfs_rqs(struct rq *rq) {}
+#endif
+
/*
* Migrate all tasks from the rq, sleeping tasks will be migrated by
* try_to_wake_up()->select_task_rq().
*/
rq->stop = NULL;
+ /* Ensure any throttled groups are reachable by pick_next_task */
+ unthrottle_offline_cfs_rqs(rq);
+
for ( ; ; ) {
/*
* There's this thread running, bail when that's the only
/* allow initial update_cfs_load() to truncate */
cfs_rq->load_stamp = 1;
#endif
+ init_cfs_rq_runtime(cfs_rq);
tg->cfs_rq[cpu] = cfs_rq;
tg->se[cpu] = se;
* 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_attach_root(rq, &def_root_domain);
#ifdef CONFIG_NO_HZ
rq->nohz_balance_kick = 0;
- init_sched_softirq_csd(&per_cpu(remote_sched_softirq_cb, i));
#endif
#endif
init_rq_hrtick(rq);
{
int i;
+ destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
+
for_each_possible_cpu(i) {
if (tg->cfs_rq)
kfree(tg->cfs_rq[i]);
tg->shares = NICE_0_LOAD;
+ init_cfs_bandwidth(tg_cfs_bandwidth(tg));
+
for_each_possible_cpu(i) {
cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
GFP_KERNEL, cpu_to_node(i));
}
#endif
-#ifdef CONFIG_RT_GROUP_SCHED
-/*
- * Ensure that the real time constraints are schedulable.
- */
-static DEFINE_MUTEX(rt_constraints_mutex);
-
+#if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
static unsigned long to_ratio(u64 period, u64 runtime)
{
if (runtime == RUNTIME_INF)
return div64_u64(runtime << 20, period);
}
+#endif
+
+#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)
u64 rt_runtime;
};
-static int tg_schedulable(struct task_group *tg, void *data)
+static int tg_rt_schedulable(struct task_group *tg, void *data)
{
struct rt_schedulable_data *d = data;
struct task_group *child;
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,
};
- return walk_tg_tree(tg_schedulable, tg_nop, &data);
+ rcu_read_lock();
+ ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
+ rcu_read_unlock();
+
+ return ret;
}
-static int tg_set_bandwidth(struct task_group *tg,
+static int tg_set_rt_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime)
{
int i, err = 0;
if (rt_runtime_us < 0)
rt_runtime = RUNTIME_INF;
- return tg_set_bandwidth(tg, rt_period, rt_runtime);
+ return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
}
long sched_group_rt_runtime(struct task_group *tg)
if (rt_period == 0)
return -EINVAL;
- return tg_set_bandwidth(tg, rt_period, rt_runtime);
+ return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
}
long sched_group_rt_period(struct task_group *tg)
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;
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
+
+ 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;
+
+ mutex_lock(&cfs_constraints_mutex);
+ ret = __cfs_schedulable(tg, period, quota);
+ if (ret)
+ goto out_unlock;
+
+ runtime_enabled = quota != RUNTIME_INF;
+ 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 && cfs_b->timer_active) {
+ /* force a reprogram */
+ cfs_b->timer_active = 0;
+ __start_cfs_bandwidth(cfs_b);
+ }
+ raw_spin_unlock_irq(&cfs_b->lock);
+
+ for_each_possible_cpu(i) {
+ struct cfs_rq *cfs_rq = tg->cfs_rq[i];
+ struct rq *rq = rq_of(cfs_rq);
+
+ raw_spin_lock_irq(&rq->lock);
+ cfs_rq->runtime_enabled = runtime_enabled;
+ cfs_rq->runtime_remaining = 0;
+
+ if (cfs_rq_throttled(cfs_rq))
+ unthrottle_cfs_rq(cfs_rq);
+ raw_spin_unlock_irq(&rq->lock);
+ }
+out_unlock:
+ mutex_unlock(&cfs_constraints_mutex);
+
+ 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(tg)->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(tg)->quota == RUNTIME_INF)
+ return -1;
+
+ quota_us = tg_cfs_bandwidth(tg)->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(tg)->quota;
+
+ if (period <= 0)
+ return -EINVAL;
+
+ 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(tg)->period);
+ do_div(cfs_period_us, NSEC_PER_USEC);
+
+ return cfs_period_us;
+}
+
+static s64 cpu_cfs_quota_read_s64(struct cgroup *cgrp, struct cftype *cft)
+{
+ return tg_get_cfs_quota(cgroup_tg(cgrp));
+}
+
+static int cpu_cfs_quota_write_s64(struct cgroup *cgrp, struct cftype *cftype,
+ s64 cfs_quota_us)
+{
+ return tg_set_cfs_quota(cgroup_tg(cgrp), cfs_quota_us);
+}
+
+static u64 cpu_cfs_period_read_u64(struct cgroup *cgrp, struct cftype *cft)
+{
+ return tg_get_cfs_period(cgroup_tg(cgrp));
+}
+
+static int cpu_cfs_period_write_u64(struct cgroup *cgrp, struct cftype *cftype,
+ u64 cfs_period_us)
+{
+ return tg_set_cfs_period(cgroup_tg(cgrp), 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(tg);
+ s64 quota = 0, parent_quota = -1;
+
+ if (!tg->parent) {
+ quota = RUNTIME_INF;
+ } else {
+ struct cfs_bandwidth *parent_b = tg_cfs_bandwidth(tg->parent);
+
+ quota = normalize_cfs_quota(tg, d);
+ parent_quota = parent_b->hierarchal_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->hierarchal_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 cgroup *cgrp, struct cftype *cft,
+ struct cgroup_map_cb *cb)
+{
+ struct task_group *tg = cgroup_tg(cgrp);
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
+
+ cb->fill(cb, "nr_periods", cfs_b->nr_periods);
+ cb->fill(cb, "nr_throttled", cfs_b->nr_throttled);
+ cb->fill(cb, "throttled_time", cfs_b->throttled_time);
+
+ return 0;
+}
+#endif /* CONFIG_CFS_BANDWIDTH */
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
.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",
+ .read_map = cpu_stats_show,
+ },
+#endif
#ifdef CONFIG_RT_GROUP_SCHED
{
.name = "rt_runtime_us",
.subsys_id = cpuacct_subsys_id,
};
#endif /* CONFIG_CGROUP_CPUACCT */
-
return cpupri;
}
-#define for_each_cpupri_active(array, idx) \
- for_each_set_bit(idx, array, CPUPRI_NR_PRIORITIES)
-
/**
* cpupri_find - find the best (lowest-pri) CPU in the system
* @cp: The cpupri context
int idx = 0;
int task_pri = convert_prio(p->prio);
- for_each_cpupri_active(cp->pri_active, idx) {
- struct cpupri_vec *vec = &cp->pri_to_cpu[idx];
+ if (task_pri >= MAX_RT_PRIO)
+ return 0;
- if (idx >= task_pri)
- break;
+ for (idx = 0; idx < task_pri; idx++) {
+ struct cpupri_vec *vec = &cp->pri_to_cpu[idx];
+ int skip = 0;
+
+ if (!atomic_read(&(vec)->count))
+ skip = 1;
+ /*
+ * When looking at the vector, we need to read the counter,
+ * do a memory barrier, then read the mask.
+ *
+ * Note: This is still all racey, but we can deal with it.
+ * Ideally, we only want to look at masks that are set.
+ *
+ * If a mask is not set, then the only thing wrong is that we
+ * did a little more work than necessary.
+ *
+ * If we read a zero count but the mask is set, because of the
+ * memory barriers, that can only happen when the highest prio
+ * task for a run queue has left the run queue, in which case,
+ * it will be followed by a pull. If the task we are processing
+ * fails to find a proper place to go, that pull request will
+ * pull this task if the run queue is running at a lower
+ * priority.
+ */
+ smp_rmb();
+
+ /* Need to do the rmb for every iteration */
+ if (skip)
+ continue;
if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
continue;
{
int *currpri = &cp->cpu_to_pri[cpu];
int oldpri = *currpri;
- unsigned long flags;
+ int do_mb = 0;
newpri = convert_prio(newpri);
* If the cpu was currently mapped to a different value, we
* need to map it to the new value then remove the old value.
* Note, we must add the new value first, otherwise we risk the
- * cpu being cleared from pri_active, and this cpu could be
- * missed for a push or pull.
+ * cpu being missed by the priority loop in cpupri_find.
*/
if (likely(newpri != CPUPRI_INVALID)) {
struct cpupri_vec *vec = &cp->pri_to_cpu[newpri];
- raw_spin_lock_irqsave(&vec->lock, flags);
-
cpumask_set_cpu(cpu, vec->mask);
- vec->count++;
- if (vec->count == 1)
- set_bit(newpri, cp->pri_active);
-
- raw_spin_unlock_irqrestore(&vec->lock, flags);
+ /*
+ * When adding a new vector, we update the mask first,
+ * do a write memory barrier, and then update the count, to
+ * make sure the vector is visible when count is set.
+ */
+ smp_mb__before_atomic_inc();
+ atomic_inc(&(vec)->count);
+ do_mb = 1;
}
if (likely(oldpri != CPUPRI_INVALID)) {
struct cpupri_vec *vec = &cp->pri_to_cpu[oldpri];
- raw_spin_lock_irqsave(&vec->lock, flags);
-
- vec->count--;
- if (!vec->count)
- clear_bit(oldpri, cp->pri_active);
+ /*
+ * Because the order of modification of the vec->count
+ * is important, we must make sure that the update
+ * of the new prio is seen before we decrement the
+ * old prio. This makes sure that the loop sees
+ * one or the other when we raise the priority of
+ * the run queue. We don't care about when we lower the
+ * priority, as that will trigger an rt pull anyway.
+ *
+ * We only need to do a memory barrier if we updated
+ * the new priority vec.
+ */
+ if (do_mb)
+ smp_mb__after_atomic_inc();
+
+ /*
+ * When removing from the vector, we decrement the counter first
+ * do a memory barrier and then clear the mask.
+ */
+ atomic_dec(&(vec)->count);
+ smp_mb__after_atomic_inc();
cpumask_clear_cpu(cpu, vec->mask);
-
- raw_spin_unlock_irqrestore(&vec->lock, flags);
}
*currpri = newpri;
for (i = 0; i < CPUPRI_NR_PRIORITIES; i++) {
struct cpupri_vec *vec = &cp->pri_to_cpu[i];
- raw_spin_lock_init(&vec->lock);
- vec->count = 0;
+ atomic_set(&vec->count, 0);
if (!zalloc_cpumask_var(&vec->mask, GFP_KERNEL))
goto cleanup;
}
#include <linux/sched.h>
#define CPUPRI_NR_PRIORITIES (MAX_RT_PRIO + 2)
-#define CPUPRI_NR_PRI_WORDS BITS_TO_LONGS(CPUPRI_NR_PRIORITIES)
#define CPUPRI_INVALID -1
#define CPUPRI_IDLE 0
/* values 2-101 are RT priorities 0-99 */
struct cpupri_vec {
- raw_spinlock_t lock;
- int count;
- cpumask_var_t mask;
+ atomic_t count;
+ cpumask_var_t mask;
};
struct cpupri {
struct cpupri_vec pri_to_cpu[CPUPRI_NR_PRIORITIES];
- long pri_active[CPUPRI_NR_PRI_WORDS];
int cpu_to_pri[NR_CPUS];
};
*/
unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
+#ifdef CONFIG_CFS_BANDWIDTH
+/*
+ * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
+ * each time a cfs_rq requests quota.
+ *
+ * Note: in the case that the slice exceeds the runtime remaining (either due
+ * to consumption or the quota being specified to be smaller than the slice)
+ * we will always only issue the remaining available time.
+ *
+ * default: 5 msec, units: microseconds
+ */
+unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
+#endif
+
static const struct sched_class fair_sched_class;
/**************************************************************
#endif /* CONFIG_FAIR_GROUP_SCHED */
+static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec);
/**************************************************************
* Scheduling class tree data structure manipulation methods:
cpuacct_charge(curtask, delta_exec);
account_group_exec_runtime(curtask, delta_exec);
}
+
+ account_cfs_rq_runtime(cfs_rq, delta_exec);
}
static inline void
}
#ifdef CONFIG_FAIR_GROUP_SCHED
+/* we need this in update_cfs_load and load-balance functions below */
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
# ifdef CONFIG_SMP
static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
int global_update)
u64 now, delta;
unsigned long load = cfs_rq->load.weight;
- if (cfs_rq->tg == &root_task_group)
+ if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq))
return;
now = rq_of(cfs_rq)->clock_task;
tg = cfs_rq->tg;
se = tg->se[cpu_of(rq_of(cfs_rq))];
- if (!se)
+ if (!se || throttled_hierarchy(cfs_rq))
return;
#ifndef CONFIG_SMP
if (likely(se->load.weight == tg->shares))
se->vruntime = vruntime;
}
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
+
static void
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
__enqueue_entity(cfs_rq, se);
se->on_rq = 1;
- if (cfs_rq->nr_running == 1)
+ if (cfs_rq->nr_running == 1) {
list_add_leaf_cfs_rq(cfs_rq);
+ check_enqueue_throttle(cfs_rq);
+ }
}
static void __clear_buddies_last(struct sched_entity *se)
__clear_buddies_skip(se);
}
+static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
+
static void
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
if (!(flags & DEQUEUE_SLEEP))
se->vruntime -= cfs_rq->min_vruntime;
+ /* return excess runtime on last dequeue */
+ return_cfs_rq_runtime(cfs_rq);
+
update_min_vruntime(cfs_rq);
update_cfs_shares(cfs_rq);
}
check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
{
unsigned long ideal_runtime, delta_exec;
+ struct sched_entity *se;
+ s64 delta;
ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
* narrow margin doesn't have to wait for a full slice.
* This also mitigates buddy induced latencies under load.
*/
- if (!sched_feat(WAKEUP_PREEMPT))
- return;
-
if (delta_exec < sysctl_sched_min_granularity)
return;
- if (cfs_rq->nr_running > 1) {
- struct sched_entity *se = __pick_first_entity(cfs_rq);
- s64 delta = curr->vruntime - se->vruntime;
+ se = __pick_first_entity(cfs_rq);
+ delta = curr->vruntime - se->vruntime;
- if (delta < 0)
- return;
+ if (delta < 0)
+ return;
- if (delta > ideal_runtime)
- resched_task(rq_of(cfs_rq)->curr);
- }
+ if (delta > ideal_runtime)
+ resched_task(rq_of(cfs_rq)->curr);
}
static void
return se;
}
+static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
+
static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
{
/*
if (prev->on_rq)
update_curr(cfs_rq);
+ /* throttle cfs_rqs exceeding runtime */
+ check_cfs_rq_runtime(cfs_rq);
+
check_spread(cfs_rq, prev);
if (prev->on_rq) {
update_stats_wait_start(cfs_rq, prev);
return;
#endif
- if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
+ if (cfs_rq->nr_running > 1)
check_preempt_tick(cfs_rq, curr);
}
+
+/**************************************************
+ * CFS bandwidth control machinery
+ */
+
+#ifdef CONFIG_CFS_BANDWIDTH
+/*
+ * default period for cfs group bandwidth.
+ * default: 0.1s, units: nanoseconds
+ */
+static inline u64 default_cfs_period(void)
+{
+ return 100000000ULL;
+}
+
+static inline u64 sched_cfs_bandwidth_slice(void)
+{
+ return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
+}
+
+/*
+ * Replenish runtime according to assigned quota and update expiration time.
+ * We use sched_clock_cpu directly instead of rq->clock to avoid adding
+ * additional synchronization around rq->lock.
+ *
+ * requires cfs_b->lock
+ */
+static void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
+{
+ u64 now;
+
+ if (cfs_b->quota == RUNTIME_INF)
+ return;
+
+ now = sched_clock_cpu(smp_processor_id());
+ cfs_b->runtime = cfs_b->quota;
+ cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
+}
+
+/* returns 0 on failure to allocate runtime */
+static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ struct task_group *tg = cfs_rq->tg;
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
+ u64 amount = 0, min_amount, expires;
+
+ /* note: this is a positive sum as runtime_remaining <= 0 */
+ min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
+
+ raw_spin_lock(&cfs_b->lock);
+ if (cfs_b->quota == RUNTIME_INF)
+ amount = min_amount;
+ else {
+ /*
+ * If the bandwidth pool has become inactive, then at least one
+ * period must have elapsed since the last consumption.
+ * Refresh the global state and ensure bandwidth timer becomes
+ * active.
+ */
+ if (!cfs_b->timer_active) {
+ __refill_cfs_bandwidth_runtime(cfs_b);
+ __start_cfs_bandwidth(cfs_b);
+ }
+
+ if (cfs_b->runtime > 0) {
+ amount = min(cfs_b->runtime, min_amount);
+ cfs_b->runtime -= amount;
+ cfs_b->idle = 0;
+ }
+ }
+ expires = cfs_b->runtime_expires;
+ raw_spin_unlock(&cfs_b->lock);
+
+ cfs_rq->runtime_remaining += amount;
+ /*
+ * we may have advanced our local expiration to account for allowed
+ * spread between our sched_clock and the one on which runtime was
+ * issued.
+ */
+ if ((s64)(expires - cfs_rq->runtime_expires) > 0)
+ cfs_rq->runtime_expires = expires;
+
+ return cfs_rq->runtime_remaining > 0;
+}
+
+/*
+ * Note: This depends on the synchronization provided by sched_clock and the
+ * fact that rq->clock snapshots this value.
+ */
+static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+ struct rq *rq = rq_of(cfs_rq);
+
+ /* if the deadline is ahead of our clock, nothing to do */
+ if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
+ return;
+
+ if (cfs_rq->runtime_remaining < 0)
+ return;
+
+ /*
+ * If the local deadline has passed we have to consider the
+ * possibility that our sched_clock is 'fast' and the global deadline
+ * has not truly expired.
+ *
+ * Fortunately we can check determine whether this the case by checking
+ * whether the global deadline has advanced.
+ */
+
+ if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
+ /* extend local deadline, drift is bounded above by 2 ticks */
+ cfs_rq->runtime_expires += TICK_NSEC;
+ } else {
+ /* global deadline is ahead, expiration has passed */
+ cfs_rq->runtime_remaining = 0;
+ }
+}
+
+static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec)
+{
+ /* dock delta_exec before expiring quota (as it could span periods) */
+ cfs_rq->runtime_remaining -= delta_exec;
+ expire_cfs_rq_runtime(cfs_rq);
+
+ if (likely(cfs_rq->runtime_remaining > 0))
+ return;
+
+ /*
+ * if we're unable to extend our runtime we resched so that the active
+ * hierarchy can be throttled
+ */
+ if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
+ resched_task(rq_of(cfs_rq)->curr);
+}
+
+static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec)
+{
+ if (!cfs_rq->runtime_enabled)
+ return;
+
+ __account_cfs_rq_runtime(cfs_rq, delta_exec);
+}
+
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
+{
+ return cfs_rq->throttled;
+}
+
+/* check whether cfs_rq, or any parent, is throttled */
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
+{
+ return cfs_rq->throttle_count;
+}
+
+/*
+ * Ensure that neither of the group entities corresponding to src_cpu or
+ * dest_cpu are members of a throttled hierarchy when performing group
+ * load-balance operations.
+ */
+static inline int throttled_lb_pair(struct task_group *tg,
+ int src_cpu, int dest_cpu)
+{
+ struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
+
+ src_cfs_rq = tg->cfs_rq[src_cpu];
+ dest_cfs_rq = tg->cfs_rq[dest_cpu];
+
+ return throttled_hierarchy(src_cfs_rq) ||
+ throttled_hierarchy(dest_cfs_rq);
+}
+
+/* updated child weight may affect parent so we have to do this bottom up */
+static int tg_unthrottle_up(struct task_group *tg, void *data)
+{
+ struct rq *rq = data;
+ struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+
+ cfs_rq->throttle_count--;
+#ifdef CONFIG_SMP
+ if (!cfs_rq->throttle_count) {
+ u64 delta = rq->clock_task - cfs_rq->load_stamp;
+
+ /* leaving throttled state, advance shares averaging windows */
+ cfs_rq->load_stamp += delta;
+ cfs_rq->load_last += delta;
+
+ /* update entity weight now that we are on_rq again */
+ update_cfs_shares(cfs_rq);
+ }
+#endif
+
+ return 0;
+}
+
+static int tg_throttle_down(struct task_group *tg, void *data)
+{
+ struct rq *rq = data;
+ struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+
+ /* group is entering throttled state, record last load */
+ if (!cfs_rq->throttle_count)
+ update_cfs_load(cfs_rq, 0);
+ cfs_rq->throttle_count++;
+
+ return 0;
+}
+
+static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
+{
+ struct rq *rq = rq_of(cfs_rq);
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+ struct sched_entity *se;
+ long task_delta, dequeue = 1;
+
+ se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
+
+ /* account load preceding throttle */
+ rcu_read_lock();
+ walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
+ rcu_read_unlock();
+
+ task_delta = cfs_rq->h_nr_running;
+ for_each_sched_entity(se) {
+ struct cfs_rq *qcfs_rq = cfs_rq_of(se);
+ /* throttled entity or throttle-on-deactivate */
+ if (!se->on_rq)
+ break;
+
+ if (dequeue)
+ dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
+ qcfs_rq->h_nr_running -= task_delta;
+
+ if (qcfs_rq->load.weight)
+ dequeue = 0;
+ }
+
+ if (!se)
+ rq->nr_running -= task_delta;
+
+ cfs_rq->throttled = 1;
+ cfs_rq->throttled_timestamp = rq->clock;
+ raw_spin_lock(&cfs_b->lock);
+ list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
+ raw_spin_unlock(&cfs_b->lock);
+}
+
+static void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
+{
+ struct rq *rq = rq_of(cfs_rq);
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+ struct sched_entity *se;
+ int enqueue = 1;
+ long task_delta;
+
+ se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
+
+ cfs_rq->throttled = 0;
+ raw_spin_lock(&cfs_b->lock);
+ cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp;
+ list_del_rcu(&cfs_rq->throttled_list);
+ raw_spin_unlock(&cfs_b->lock);
+ cfs_rq->throttled_timestamp = 0;
+
+ update_rq_clock(rq);
+ /* update hierarchical throttle state */
+ walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
+
+ if (!cfs_rq->load.weight)
+ return;
+
+ task_delta = cfs_rq->h_nr_running;
+ for_each_sched_entity(se) {
+ if (se->on_rq)
+ enqueue = 0;
+
+ cfs_rq = cfs_rq_of(se);
+ if (enqueue)
+ enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
+ cfs_rq->h_nr_running += task_delta;
+
+ if (cfs_rq_throttled(cfs_rq))
+ break;
+ }
+
+ if (!se)
+ rq->nr_running += task_delta;
+
+ /* determine whether we need to wake up potentially idle cpu */
+ if (rq->curr == rq->idle && rq->cfs.nr_running)
+ resched_task(rq->curr);
+}
+
+static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
+ u64 remaining, u64 expires)
+{
+ struct cfs_rq *cfs_rq;
+ u64 runtime = remaining;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
+ throttled_list) {
+ struct rq *rq = rq_of(cfs_rq);
+
+ raw_spin_lock(&rq->lock);
+ if (!cfs_rq_throttled(cfs_rq))
+ goto next;
+
+ runtime = -cfs_rq->runtime_remaining + 1;
+ if (runtime > remaining)
+ runtime = remaining;
+ remaining -= runtime;
+
+ cfs_rq->runtime_remaining += runtime;
+ cfs_rq->runtime_expires = expires;
+
+ /* we check whether we're throttled above */
+ if (cfs_rq->runtime_remaining > 0)
+ unthrottle_cfs_rq(cfs_rq);
+
+next:
+ raw_spin_unlock(&rq->lock);
+
+ if (!remaining)
+ break;
+ }
+ rcu_read_unlock();
+
+ return remaining;
+}
+
+/*
+ * Responsible for refilling a task_group's bandwidth and unthrottling its
+ * cfs_rqs as appropriate. If there has been no activity within the last
+ * period the timer is deactivated until scheduling resumes; cfs_b->idle is
+ * used to track this state.
+ */
+static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
+{
+ u64 runtime, runtime_expires;
+ int idle = 1, throttled;
+
+ raw_spin_lock(&cfs_b->lock);
+ /* no need to continue the timer with no bandwidth constraint */
+ if (cfs_b->quota == RUNTIME_INF)
+ goto out_unlock;
+
+ throttled = !list_empty(&cfs_b->throttled_cfs_rq);
+ /* idle depends on !throttled (for the case of a large deficit) */
+ idle = cfs_b->idle && !throttled;
+ cfs_b->nr_periods += overrun;
+
+ /* if we're going inactive then everything else can be deferred */
+ if (idle)
+ goto out_unlock;
+
+ __refill_cfs_bandwidth_runtime(cfs_b);
+
+ if (!throttled) {
+ /* mark as potentially idle for the upcoming period */
+ cfs_b->idle = 1;
+ goto out_unlock;
+ }
+
+ /* account preceding periods in which throttling occurred */
+ cfs_b->nr_throttled += overrun;
+
+ /*
+ * There are throttled entities so we must first use the new bandwidth
+ * to unthrottle them before making it generally available. This
+ * ensures that all existing debts will be paid before a new cfs_rq is
+ * allowed to run.
+ */
+ runtime = cfs_b->runtime;
+ runtime_expires = cfs_b->runtime_expires;
+ cfs_b->runtime = 0;
+
+ /*
+ * This check is repeated as we are holding onto the new bandwidth
+ * while we unthrottle. This can potentially race with an unthrottled
+ * group trying to acquire new bandwidth from the global pool.
+ */
+ while (throttled && runtime > 0) {
+ raw_spin_unlock(&cfs_b->lock);
+ /* we can't nest cfs_b->lock while distributing bandwidth */
+ runtime = distribute_cfs_runtime(cfs_b, runtime,
+ runtime_expires);
+ raw_spin_lock(&cfs_b->lock);
+
+ throttled = !list_empty(&cfs_b->throttled_cfs_rq);
+ }
+
+ /* return (any) remaining runtime */
+ cfs_b->runtime = runtime;
+ /*
+ * While we are ensured activity in the period following an
+ * unthrottle, this also covers the case in which the new bandwidth is
+ * insufficient to cover the existing bandwidth deficit. (Forcing the
+ * timer to remain active while there are any throttled entities.)
+ */
+ cfs_b->idle = 0;
+out_unlock:
+ if (idle)
+ cfs_b->timer_active = 0;
+ raw_spin_unlock(&cfs_b->lock);
+
+ return idle;
+}
+
+/* a cfs_rq won't donate quota below this amount */
+static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
+/* minimum remaining period time to redistribute slack quota */
+static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
+/* how long we wait to gather additional slack before distributing */
+static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
+
+/* are we near the end of the current quota period? */
+static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
+{
+ struct hrtimer *refresh_timer = &cfs_b->period_timer;
+ u64 remaining;
+
+ /* if the call-back is running a quota refresh is already occurring */
+ if (hrtimer_callback_running(refresh_timer))
+ return 1;
+
+ /* is a quota refresh about to occur? */
+ remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
+ if (remaining < min_expire)
+ return 1;
+
+ return 0;
+}
+
+static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
+{
+ u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
+
+ /* if there's a quota refresh soon don't bother with slack */
+ if (runtime_refresh_within(cfs_b, min_left))
+ return;
+
+ start_bandwidth_timer(&cfs_b->slack_timer,
+ ns_to_ktime(cfs_bandwidth_slack_period));
+}
+
+/* we know any runtime found here is valid as update_curr() precedes return */
+static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+ s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
+
+ if (slack_runtime <= 0)
+ return;
+
+ raw_spin_lock(&cfs_b->lock);
+ if (cfs_b->quota != RUNTIME_INF &&
+ cfs_rq->runtime_expires == cfs_b->runtime_expires) {
+ cfs_b->runtime += slack_runtime;
+
+ /* we are under rq->lock, defer unthrottling using a timer */
+ if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
+ !list_empty(&cfs_b->throttled_cfs_rq))
+ start_cfs_slack_bandwidth(cfs_b);
+ }
+ raw_spin_unlock(&cfs_b->lock);
+
+ /* even if it's not valid for return we don't want to try again */
+ cfs_rq->runtime_remaining -= slack_runtime;
+}
+
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ if (!cfs_rq->runtime_enabled || !cfs_rq->nr_running)
+ return;
+
+ __return_cfs_rq_runtime(cfs_rq);
+}
+
+/*
+ * This is done with a timer (instead of inline with bandwidth return) since
+ * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
+ */
+static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
+{
+ u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
+ u64 expires;
+
+ /* confirm we're still not at a refresh boundary */
+ if (runtime_refresh_within(cfs_b, min_bandwidth_expiration))
+ return;
+
+ raw_spin_lock(&cfs_b->lock);
+ if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
+ runtime = cfs_b->runtime;
+ cfs_b->runtime = 0;
+ }
+ expires = cfs_b->runtime_expires;
+ raw_spin_unlock(&cfs_b->lock);
+
+ if (!runtime)
+ return;
+
+ runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
+
+ raw_spin_lock(&cfs_b->lock);
+ if (expires == cfs_b->runtime_expires)
+ cfs_b->runtime = runtime;
+ raw_spin_unlock(&cfs_b->lock);
+}
+
+/*
+ * When a group wakes up we want to make sure that its quota is not already
+ * expired/exceeded, otherwise it may be allowed to steal additional ticks of
+ * runtime as update_curr() throttling can not not trigger until it's on-rq.
+ */
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
+{
+ /* an active group must be handled by the update_curr()->put() path */
+ if (!cfs_rq->runtime_enabled || cfs_rq->curr)
+ return;
+
+ /* ensure the group is not already throttled */
+ if (cfs_rq_throttled(cfs_rq))
+ return;
+
+ /* update runtime allocation */
+ account_cfs_rq_runtime(cfs_rq, 0);
+ if (cfs_rq->runtime_remaining <= 0)
+ throttle_cfs_rq(cfs_rq);
+}
+
+/* conditionally throttle active cfs_rq's from put_prev_entity() */
+static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
+ return;
+
+ /*
+ * it's possible for a throttled entity to be forced into a running
+ * state (e.g. set_curr_task), in this case we're finished.
+ */
+ if (cfs_rq_throttled(cfs_rq))
+ return;
+
+ throttle_cfs_rq(cfs_rq);
+}
+#else
+static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec) {}
+static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
+static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
+
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
+{
+ return 0;
+}
+
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
+{
+ return 0;
+}
+
+static inline int throttled_lb_pair(struct task_group *tg,
+ int src_cpu, int dest_cpu)
+{
+ return 0;
+}
+#endif
+
/**************************************************
* CFS operations on tasks:
*/
break;
cfs_rq = cfs_rq_of(se);
enqueue_entity(cfs_rq, se, flags);
+
+ /*
+ * end evaluation on encountering a throttled cfs_rq
+ *
+ * note: in the case of encountering a throttled cfs_rq we will
+ * post the final h_nr_running increment below.
+ */
+ if (cfs_rq_throttled(cfs_rq))
+ break;
+ cfs_rq->h_nr_running++;
+
flags = ENQUEUE_WAKEUP;
}
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
+ cfs_rq->h_nr_running++;
+
+ if (cfs_rq_throttled(cfs_rq))
+ break;
update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq);
}
+ if (!se)
+ inc_nr_running(rq);
hrtick_update(rq);
}
cfs_rq = cfs_rq_of(se);
dequeue_entity(cfs_rq, se, flags);
+ /*
+ * end evaluation on encountering a throttled cfs_rq
+ *
+ * note: in the case of encountering a throttled cfs_rq we will
+ * post the final h_nr_running decrement below.
+ */
+ if (cfs_rq_throttled(cfs_rq))
+ break;
+ cfs_rq->h_nr_running--;
+
/* Don't dequeue parent if it has other entities besides us */
if (cfs_rq->load.weight) {
/*
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
+ cfs_rq->h_nr_running--;
+
+ if (cfs_rq_throttled(cfs_rq))
+ break;
update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq);
}
+ if (!se)
+ dec_nr_running(rq);
hrtick_update(rq);
}
return wl;
}
-
#else
static inline unsigned long effective_load(struct task_group *tg, int cpu,
/* Skip over this group if it has no CPUs allowed */
if (!cpumask_intersects(sched_group_cpus(group),
- &p->cpus_allowed))
+ tsk_cpus_allowed(p)))
continue;
local_group = cpumask_test_cpu(this_cpu,
int i;
/* Traverse only the allowed CPUs */
- for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) {
+ for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
load = weighted_cpuload(i);
if (load < min_load || (load == min_load && i == this_cpu)) {
if (!(sd->flags & SD_SHARE_PKG_RESOURCES))
break;
- for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
+ for_each_cpu_and(i, sched_domain_span(sd), tsk_cpus_allowed(p)) {
if (idle_cpu(i)) {
target = i;
break;
int sync = wake_flags & WF_SYNC;
if (sd_flag & SD_BALANCE_WAKE) {
- if (cpumask_test_cpu(cpu, &p->cpus_allowed))
+ if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
want_affine = 1;
new_cpu = prev_cpu;
}
if (unlikely(se == pse))
return;
+ /*
+ * This is possible from callers such as pull_task(), in which we
+ * unconditionally check_prempt_curr() after an enqueue (which may have
+ * lead to a throttle). This both saves work and prevents false
+ * next-buddy nomination below.
+ */
+ if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
+ return;
+
if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
set_next_buddy(pse);
next_buddy_marked = 1;
/*
* We can come here with TIF_NEED_RESCHED already set from new task
* wake up path.
+ *
+ * Note: this also catches the edge-case of curr being in a throttled
+ * group (e.g. via set_curr_task), since update_curr() (in the
+ * enqueue of curr) will have resulted in resched being set. This
+ * prevents us from potentially nominating it as a false LAST_BUDDY
+ * below.
*/
if (test_tsk_need_resched(curr))
return;
if (unlikely(p->policy != SCHED_NORMAL))
return;
-
- if (!sched_feat(WAKEUP_PREEMPT))
- return;
-
find_matching_se(&se, &pse);
update_curr(cfs_rq_of(se));
BUG_ON(!pse);
{
struct sched_entity *se = &p->se;
- if (!se->on_rq)
+ /* throttled hierarchies are not runnable */
+ if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
return false;
/* Tell the scheduler that we'd really like pse to run next. */
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
- if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
+ if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p))) {
schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
return 0;
}
for_each_leaf_cfs_rq(busiest, cfs_rq) {
list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
+ if (throttled_lb_pair(task_group(p),
+ busiest->cpu, this_cpu))
+ break;
if (!can_migrate_task(p, busiest, this_cpu,
sd, idle, &pinned))
* Iterates the task_group tree in a bottom up fashion, see
* list_add_leaf_cfs_rq() for details.
*/
- for_each_leaf_cfs_rq(rq, cfs_rq)
+ for_each_leaf_cfs_rq(rq, cfs_rq) {
+ /* throttled entities do not contribute to load */
+ if (throttled_hierarchy(cfs_rq))
+ continue;
+
update_shares_cpu(cfs_rq->tg, cpu);
+ }
rcu_read_unlock();
}
u64 rem_load, moved_load;
/*
- * empty group
+ * empty group or part of a throttled hierarchy
*/
- if (!busiest_cfs_rq->task_weight)
+ if (!busiest_cfs_rq->task_weight ||
+ throttled_lb_pair(busiest_cfs_rq->tg, cpu_of(busiest), this_cpu))
continue;
rem_load = (u64)rem_load_move * busiest_weight;
* moved to this_cpu
*/
if (!cpumask_test_cpu(this_cpu,
- &busiest->curr->cpus_allowed)) {
+ tsk_cpus_allowed(busiest->curr))) {
raw_spin_unlock_irqrestore(&busiest->lock,
flags);
all_pinned = 1;
}
#ifdef CONFIG_NO_HZ
-
-static DEFINE_PER_CPU(struct call_single_data, remote_sched_softirq_cb);
-
-static void trigger_sched_softirq(void *data)
-{
- raise_softirq_irqoff(SCHED_SOFTIRQ);
-}
-
-static inline void init_sched_softirq_csd(struct call_single_data *csd)
-{
- csd->func = trigger_sched_softirq;
- csd->info = NULL;
- csd->flags = 0;
- csd->priv = 0;
-}
-
/*
* idle load balancing details
* - One of the idle CPUs nominates itself as idle load_balancer, while
struct sched_domain *sd;
for_each_domain(cpu, sd)
- if (sd && (sd->flags & flag))
+ if (sd->flags & flag)
break;
return sd;
}
if (!cpu_rq(ilb_cpu)->nohz_balance_kick) {
- struct call_single_data *cp;
-
cpu_rq(ilb_cpu)->nohz_balance_kick = 1;
- cp = &per_cpu(remote_sched_softirq_cb, cpu);
- __smp_call_function_single(ilb_cpu, cp, 0);
+
+ smp_mb();
+ /*
+ * Use smp_send_reschedule() instead of resched_cpu().
+ * This way we generate a sched IPI on the target cpu which
+ * is idle. And the softirq performing nohz idle load balance
+ * will be run before returning from the IPI.
+ */
+ smp_send_reschedule(ilb_cpu);
}
return;
}
if (time_before(now, nohz.next_balance))
return 0;
- if (rq->idle_at_tick)
+ if (idle_cpu(cpu))
return 0;
first_pick_cpu = atomic_read(&nohz.first_pick_cpu);
{
int this_cpu = smp_processor_id();
struct rq *this_rq = cpu_rq(this_cpu);
- enum cpu_idle_type idle = this_rq->idle_at_tick ?
+ enum cpu_idle_type idle = this_rq->idle_balance ?
CPU_IDLE : CPU_NOT_IDLE;
rebalance_domains(this_cpu, idle);
{
struct sched_entity *se = &rq->curr->se;
- for_each_sched_entity(se)
- set_next_entity(cfs_rq_of(se), se);
+ for_each_sched_entity(se) {
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+ set_next_entity(cfs_rq, se);
+ /* ensure bandwidth has been allocated on our new cfs_rq */
+ account_cfs_rq_runtime(cfs_rq, 0);
+ }
}
#ifdef CONFIG_FAIR_GROUP_SCHED
*/
SCHED_FEAT(START_DEBIT, 1)
-/*
- * Should wakeups try to preempt running tasks.
- */
-SCHED_FEAT(WAKEUP_PREEMPT, 1)
-
/*
* Based on load and program behaviour, see if it makes sense to place
* a newly woken task on the same cpu as the task that woke it --
update_rt_migration(rt_rq);
}
+static inline int has_pushable_tasks(struct rq *rq)
+{
+ return !plist_head_empty(&rq->rt.pushable_tasks);
+}
+
static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
{
plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
plist_node_init(&p->pushable_tasks, p->prio);
plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
+
+ /* Update the highest prio pushable task */
+ if (p->prio < rq->rt.highest_prio.next)
+ rq->rt.highest_prio.next = p->prio;
}
static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
{
plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
-}
-static inline int has_pushable_tasks(struct rq *rq)
-{
- return !plist_head_empty(&rq->rt.pushable_tasks);
+ /* Update the new highest prio pushable task */
+ if (has_pushable_tasks(rq)) {
+ p = plist_first_entry(&rq->rt.pushable_tasks,
+ struct task_struct, pushable_tasks);
+ rq->rt.highest_prio.next = p->prio;
+ } else
+ rq->rt.highest_prio.next = MAX_RT_PRIO;
}
#else
if (rt_rq->rt_time > runtime) {
rt_rq->rt_throttled = 1;
+ printk_once(KERN_WARNING "sched: RT throttling activated\n");
if (rt_rq_throttled(rt_rq)) {
sched_rt_rq_dequeue(rt_rq);
return 1;
#if defined CONFIG_SMP
-static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
-
-static inline int next_prio(struct rq *rq)
-{
- struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
-
- if (next && rt_prio(next->prio))
- return next->prio;
- else
- return MAX_RT_PRIO;
-}
-
static void
inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
{
struct rq *rq = rq_of_rt_rq(rt_rq);
- if (prio < prev_prio) {
-
- /*
- * If the new task is higher in priority than anything on the
- * run-queue, we know that the previous high becomes our
- * next-highest.
- */
- rt_rq->highest_prio.next = prev_prio;
-
- if (rq->online)
- cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
-
- } else if (prio == rt_rq->highest_prio.curr)
- /*
- * If the next task is equal in priority to the highest on
- * the run-queue, then we implicitly know that the next highest
- * task cannot be any lower than current
- */
- rt_rq->highest_prio.next = prio;
- else if (prio < rt_rq->highest_prio.next)
- /*
- * Otherwise, we need to recompute next-highest
- */
- rt_rq->highest_prio.next = next_prio(rq);
+ if (rq->online && prio < prev_prio)
+ cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
}
static void
{
struct rq *rq = rq_of_rt_rq(rt_rq);
- if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
- rt_rq->highest_prio.next = next_prio(rq);
-
if (rq->online && rt_rq->highest_prio.curr != prev_prio)
cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
}
if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p);
+
+ inc_nr_running(rq);
}
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
dequeue_rt_entity(rt_se);
dequeue_pushable_task(rq, p);
+
+ dec_nr_running(rq);
}
/*
struct rq *rq;
int cpu;
- if (sd_flag != SD_BALANCE_WAKE)
- return smp_processor_id();
-
cpu = task_cpu(p);
+
+ /* For anything but wake ups, just return the task_cpu */
+ if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
+ goto out;
+
rq = cpu_rq(cpu);
rcu_read_lock();
}
rcu_read_unlock();
+out:
return cpu;
}
static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
{
update_curr_rt(rq);
- p->se.exec_start = 0;
/*
* The previous task needs to be made eligible for pushing
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
if (!task_running(rq, p) &&
- (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
+ (cpu < 0 || cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) &&
(p->rt.nr_cpus_allowed > 1))
return 1;
return 0;
*/
if (unlikely(task_rq(task) != rq ||
!cpumask_test_cpu(lowest_rq->cpu,
- &task->cpus_allowed) ||
+ tsk_cpus_allowed(task)) ||
task_running(rq, task) ||
!task->on_rq)) {
{
struct task_struct *next_task;
struct rq *lowest_rq;
+ int ret = 0;
if (!rq->rt.overloaded)
return 0;
if (!lowest_rq) {
struct task_struct *task;
/*
- * find lock_lowest_rq releases rq->lock
+ * find_lock_lowest_rq releases rq->lock
* so it is possible that next_task has migrated.
*
* We need to make sure that the task is still on the same
task = pick_next_pushable_task(rq);
if (task_cpu(next_task) == rq->cpu && task == next_task) {
/*
- * If we get here, the task hasn't moved at all, but
- * it has failed to push. We will not try again,
- * since the other cpus will pull from us when they
- * are ready.
+ * The task hasn't migrated, and is still the next
+ * eligible task, but we failed to find a run-queue
+ * to push it to. Do not retry in this case, since
+ * other cpus will pull from us when ready.
*/
- dequeue_pushable_task(rq, next_task);
goto out;
}
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu);
activate_task(lowest_rq, next_task, 0);
+ ret = 1;
resched_task(lowest_rq->curr);
out:
put_task_struct(next_task);
- return 1;
+ return ret;
}
static void push_rt_tasks(struct rq *rq)
update_rt_migration(&rq->rt);
}
-
- cpumask_copy(&p->cpus_allowed, new_mask);
- p->rt.nr_cpus_allowed = weight;
}
/* Assumes rq->lock is held */
rcu_read_unlock();
}
#endif /* CONFIG_SCHED_DEBUG */
-
static void
enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
{
+ inc_nr_running(rq);
}
static void
dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
{
+ dec_nr_running(rq);
}
static void yield_task_stop(struct rq *rq)
.extra2 = &one,
},
#endif
+#ifdef CONFIG_CFS_BANDWIDTH
+ {
+ .procname = "sched_cfs_bandwidth_slice_us",
+ .data = &sysctl_sched_cfs_bandwidth_slice,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
+ },
+#endif
#ifdef CONFIG_PROVE_LOCKING
{
.procname = "prove_locking",
so its calculations are in fixed point. Modules can select this
when they require this function. Module will be called cordic.
-config LLIST
- bool
-
endmenu
obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o \
- bsearch.o find_last_bit.o find_next_bit.o
+ bsearch.o find_last_bit.o find_next_bit.o llist.o
obj-y += kstrtox.o
obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
obj-$(CONFIG_CORDIC) += cordic.o
-obj-$(CONFIG_LLIST) += llist.o
-
hostprogs-y := gen_crc32table
clean-files := crc32table.h
*
* The basic atomic operation of this list is cmpxchg on long. On
* architectures that don't have NMI-safe cmpxchg implementation, the
- * list can NOT be used in NMI handler. So code uses the list in NMI
- * handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
+ * list can NOT be used in NMI handlers. So code that uses the list in
+ * an NMI handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
*
* Copyright 2010,2011 Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
#include <asm/system.h>
-/**
- * llist_add - add a new entry
- * @new: new entry to be added
- * @head: the head for your lock-less list
- */
-void llist_add(struct llist_node *new, struct llist_head *head)
-{
- struct llist_node *entry, *old_entry;
-
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
- BUG_ON(in_nmi());
-#endif
-
- entry = head->first;
- do {
- old_entry = entry;
- new->next = entry;
- cpu_relax();
- } while ((entry = cmpxchg(&head->first, old_entry, new)) != old_entry);
-}
-EXPORT_SYMBOL_GPL(llist_add);
-
/**
* llist_add_batch - add several linked entries in batch
* @new_first: first entry in batch to be added
* @new_last: last entry in batch to be added
* @head: the head for your lock-less list
+ *
+ * Return whether list is empty before adding.
*/
-void llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
+bool llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
struct llist_head *head)
{
struct llist_node *entry, *old_entry;
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
- BUG_ON(in_nmi());
-#endif
-
entry = head->first;
- do {
+ for (;;) {
old_entry = entry;
new_last->next = entry;
- cpu_relax();
- } while ((entry = cmpxchg(&head->first, old_entry, new_first)) != old_entry);
+ entry = cmpxchg(&head->first, old_entry, new_first);
+ if (entry == old_entry)
+ break;
+ }
+
+ return old_entry == NULL;
}
EXPORT_SYMBOL_GPL(llist_add_batch);
{
struct llist_node *entry, *old_entry, *next;
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
- BUG_ON(in_nmi());
-#endif
-
entry = head->first;
- do {
+ for (;;) {
if (entry == NULL)
return NULL;
old_entry = entry;
next = entry->next;
- cpu_relax();
- } while ((entry = cmpxchg(&head->first, old_entry, next)) != old_entry);
+ entry = cmpxchg(&head->first, old_entry, next);
+ if (entry == old_entry)
+ break;
+ }
return entry;
}
EXPORT_SYMBOL_GPL(llist_del_first);
-
-/**
- * llist_del_all - delete all entries from lock-less list
- * @head: the head of lock-less list to delete all entries
- *
- * If list is empty, return NULL, otherwise, delete all entries and
- * return the pointer to the first entry. The order of entries
- * deleted is from the newest to the oldest added one.
- */
-struct llist_node *llist_del_all(struct llist_head *head)
-{
-#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
- BUG_ON(in_nmi());
-#endif
-
- return xchg(&head->first, NULL);
-}
-EXPORT_SYMBOL_GPL(llist_del_all);
* Kernel threads bound to a single CPU can safely use
* smp_processor_id():
*/
- if (cpumask_equal(¤t->cpus_allowed, cpumask_of(this_cpu)))
+ if (cpumask_equal(tsk_cpus_allowed(current), cpumask_of(this_cpu)))
goto out;
/*
git.openpandora.org / pandora-kernel.git / commitdiff