/* Standard hot unplug procedure */
idle_task_exit();
- current->active_mm = NULL; /* for sanity */
cpu = smp_processor_id();
DBG("CPU%d offline\n", cpu);
generic_set_cpu_dead(cpu);
* busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed
*/
+/* flags share CSD_FLAG_ space */
+
#define IRQ_WORK_PENDING BIT(0)
#define IRQ_WORK_BUSY BIT(1)
#define IRQ_WORK_CLAIMED (IRQ_WORK_PENDING | IRQ_WORK_BUSY)
+/*
+ * structure shares layout with single_call_data_t.
+ */
struct irq_work {
- atomic_t flags;
struct llist_node llnode;
+ atomic_t flags;
void (*func)(struct irq_work *);
};
void irq_work_run(void);
bool irq_work_needs_cpu(void);
+void irq_work_single(void *arg);
#else
static inline bool irq_work_needs_cpu(void) { return false; }
static inline void irq_work_run(void) { }
+static inline void irq_work_single(void *arg) { }
#endif
#endif /* _LINUX_IRQ_WORK_H */
#ifdef CONFIG_SMP
struct llist_node wake_entry;
+ unsigned int wake_entry_type;
int on_cpu;
#ifdef CONFIG_THREAD_INFO_IN_TASK
/* Current CPU: */
})
#ifdef CONFIG_SMP
-void scheduler_ipi(void);
+static __always_inline void scheduler_ipi(void)
+{
+ /*
+ * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
+ * TIF_NEED_RESCHED remotely (for the first time) will also send
+ * this IPI.
+ */
+ preempt_fold_need_resched();
+}
extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
#else
static inline void scheduler_ipi(void) { }
__mmdrop(mm);
}
+void mmdrop(struct mm_struct *mm);
+
/*
* This has to be called after a get_task_mm()/mmget_not_zero()
* followed by taking the mmap_sem for writing before modifying the
*/
#ifdef CONFIG_SMP
-#define SD_LOAD_BALANCE 0x0001 /* Do load balancing on this domain. */
-#define SD_BALANCE_NEWIDLE 0x0002 /* Balance when about to become idle */
-#define SD_BALANCE_EXEC 0x0004 /* Balance on exec */
-#define SD_BALANCE_FORK 0x0008 /* Balance on fork, clone */
-#define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */
-#define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */
-#define SD_ASYM_CPUCAPACITY 0x0040 /* Domain members have different CPU capacities */
-#define SD_SHARE_CPUCAPACITY 0x0080 /* Domain members share CPU capacity */
-#define SD_SHARE_POWERDOMAIN 0x0100 /* Domain members share power domain */
-#define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share CPU pkg resources */
-#define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */
-#define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */
-#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
-#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */
-#define SD_NUMA 0x4000 /* cross-node balancing */
+#define SD_BALANCE_NEWIDLE 0x0001 /* Balance when about to become idle */
+#define SD_BALANCE_EXEC 0x0002 /* Balance on exec */
+#define SD_BALANCE_FORK 0x0004 /* Balance on fork, clone */
+#define SD_BALANCE_WAKE 0x0008 /* Balance on wakeup */
+#define SD_WAKE_AFFINE 0x0010 /* Wake task to waking CPU */
+#define SD_ASYM_CPUCAPACITY 0x0020 /* Domain members have different CPU capacities */
+#define SD_SHARE_CPUCAPACITY 0x0040 /* Domain members share CPU capacity */
+#define SD_SHARE_POWERDOMAIN 0x0080 /* Domain members share power domain */
+#define SD_SHARE_PKG_RESOURCES 0x0100 /* Domain members share CPU pkg resources */
+#define SD_SERIALIZE 0x0200 /* Only a single load balancing instance */
+#define SD_ASYM_PACKING 0x0400 /* Place busy groups earlier in the domain */
+#define SD_PREFER_SIBLING 0x0800 /* Prefer to place tasks in a sibling domain */
+#define SD_OVERLAP 0x1000 /* sched_domains of this level overlap */
+#define SD_NUMA 0x2000 /* cross-node balancing */
#ifdef CONFIG_SCHED_SMT
static inline int cpu_smt_flags(void)
typedef void (*smp_call_func_t)(void *info);
typedef bool (*smp_cond_func_t)(int cpu, void *info);
+
+enum {
+ CSD_FLAG_LOCK = 0x01,
+
+ /* IRQ_WORK_flags */
+
+ CSD_TYPE_ASYNC = 0x00,
+ CSD_TYPE_SYNC = 0x10,
+ CSD_TYPE_IRQ_WORK = 0x20,
+ CSD_TYPE_TTWU = 0x30,
+ CSD_FLAG_TYPE_MASK = 0xF0,
+};
+
+/*
+ * structure shares (partial) layout with struct irq_work
+ */
struct __call_single_data {
struct llist_node llist;
+ unsigned int flags;
smp_call_func_t func;
void *info;
- unsigned int flags;
};
/* Use __aligned() to avoid to use 2 cache lines for 1 csd */
typedef struct __call_single_data call_single_data_t
__aligned(sizeof(struct __call_single_data));
+/*
+ * Enqueue a llist_node on the call_single_queue; be very careful, read
+ * flush_smp_call_function_queue() in detail.
+ */
+extern void __smp_call_single_queue(int cpu, struct llist_node *node);
+
/* total number of cpus in this system (may exceed NR_CPUS) */
extern unsigned int total_cpus;
#include <asm/current.h>
/*
- * BROKEN wait-queues.
- *
- * These "simple" wait-queues are broken garbage, and should never be
- * used. The comments below claim that they are "similar" to regular
- * wait-queues, but the semantics are actually completely different, and
- * every single user we have ever had has been buggy (or pointless).
- *
- * A "swake_up_one()" only wakes up _one_ waiter, which is not at all what
- * "wake_up()" does, and has led to problems. In other cases, it has
- * been fine, because there's only ever one waiter (kvm), but in that
- * case gthe whole "simple" wait-queue is just pointless to begin with,
- * since there is no "queue". Use "wake_up_process()" with a direct
- * pointer instead.
- *
- * While these are very similar to regular wait queues (wait.h) the most
- * important difference is that the simple waitqueue allows for deterministic
- * behaviour -- IOW it has strictly bounded IRQ and lock hold times.
+ * Simple waitqueues are semantically very different to regular wait queues
+ * (wait.h). The most important difference is that the simple waitqueue allows
+ * for deterministic behaviour -- IOW it has strictly bounded IRQ and lock hold
+ * times.
*
* Mainly, this is accomplished by two things. Firstly not allowing swake_up_all
* from IRQ disabled, and dropping the lock upon every wakeup, giving a higher
* sleeper state.
*
* - the !exclusive mode; because that leads to O(n) wakeups, everything is
- * exclusive.
+ * exclusive. As such swake_up_one will only ever awake _one_ waiter.
*
* - custom wake callback functions; because you cannot give any guarantees
* about random code. This also allows swait to be used in RT, such that
*
* This code is licenced under the GPL.
*/
+#include <linux/sched/mm.h>
#include <linux/proc_fs.h>
#include <linux/smp.h>
#include <linux/init.h>
return bringup_wait_for_ap(cpu);
}
+static int finish_cpu(unsigned int cpu)
+{
+ struct task_struct *idle = idle_thread_get(cpu);
+ struct mm_struct *mm = idle->active_mm;
+
+ /*
+ * idle_task_exit() will have switched to &init_mm, now
+ * clean up any remaining active_mm state.
+ */
+ if (mm != &init_mm)
+ idle->active_mm = &init_mm;
+ mmdrop(mm);
+ return 0;
+}
+
/*
* Hotplug state machine related functions
*/
[CPUHP_BRINGUP_CPU] = {
.name = "cpu:bringup",
.startup.single = bringup_cpu,
- .teardown.single = NULL,
+ .teardown.single = finish_cpu,
.cant_stop = true,
},
/* Final state before CPU kills itself */
struct task_struct *tsk = current;
int group_dead;
- profile_task_exit(tsk);
- kcov_task_exit(tsk);
+ /*
+ * We can get here from a kernel oops, sometimes with preemption off.
+ * Start by checking for critical errors.
+ * Then fix up important state like USER_DS and preemption.
+ * Then do everything else.
+ */
WARN_ON(blk_needs_flush_plug(tsk));
*/
set_fs(USER_DS);
+ if (unlikely(in_atomic())) {
+ pr_info("note: %s[%d] exited with preempt_count %d\n",
+ current->comm, task_pid_nr(current),
+ preempt_count());
+ preempt_count_set(PREEMPT_ENABLED);
+ }
+
+ profile_task_exit(tsk);
+ kcov_task_exit(tsk);
+
ptrace_event(PTRACE_EVENT_EXIT, code);
validate_creds_for_do_exit(tsk);
exit_signals(tsk); /* sets PF_EXITING */
- if (unlikely(in_atomic())) {
- pr_info("note: %s[%d] exited with preempt_count %d\n",
- current->comm, task_pid_nr(current),
- preempt_count());
- preempt_count_set(PREEMPT_ENABLED);
- }
-
/* sync mm's RSS info before statistics gathering */
if (tsk->mm)
sync_mm_rss(tsk->mm);
{
int oflags;
- oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->flags);
+ oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->flags);
/*
* If the work is already pending, no need to raise the IPI.
* The pairing atomic_fetch_andnot() in irq_work_run() makes sure
if (cpu != smp_processor_id()) {
/* Arch remote IPI send/receive backend aren't NMI safe */
WARN_ON_ONCE(in_nmi());
- if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
- arch_send_call_function_single_ipi(cpu);
+ __smp_call_single_queue(cpu, &work->llnode);
} else {
__irq_work_queue_local(work);
}
return true;
}
+void irq_work_single(void *arg)
+{
+ struct irq_work *work = arg;
+ int flags;
+
+ /*
+ * Clear the PENDING bit, after this point the @work
+ * can be re-used.
+ * Make it immediately visible so that other CPUs trying
+ * to claim that work don't rely on us to handle their data
+ * while we are in the middle of the func.
+ */
+ flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
+
+ lockdep_irq_work_enter(work);
+ work->func(work);
+ lockdep_irq_work_exit(work);
+ /*
+ * Clear the BUSY bit and return to the free state if
+ * no-one else claimed it meanwhile.
+ */
+ flags &= ~IRQ_WORK_PENDING;
+ (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
+}
+
static void irq_work_run_list(struct llist_head *list)
{
struct irq_work *work, *tmp;
return;
llnode = llist_del_all(list);
- llist_for_each_entry_safe(work, tmp, llnode, llnode) {
- int flags;
- /*
- * Clear the PENDING bit, after this point the @work
- * can be re-used.
- * Make it immediately visible so that other CPUs trying
- * to claim that work don't rely on us to handle their data
- * while we are in the middle of the func.
- */
- flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
-
- lockdep_irq_work_enter(work);
- work->func(work);
- lockdep_irq_work_exit(work);
- /*
- * Clear the BUSY bit and return to the free state if
- * no-one else claimed it meanwhile.
- */
- flags &= ~IRQ_WORK_PENDING;
- (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
- }
+ llist_for_each_entry_safe(work, tmp, llnode, llnode)
+ irq_work_single(work);
}
/*
#include "../smpboot.h"
#include "pelt.h"
+#include "smp.h"
#define CREATE_TRACE_POINTS
#include <trace/events/sched.h>
update_rq_clock_task(rq, delta);
}
+static inline void
+rq_csd_init(struct rq *rq, call_single_data_t *csd, smp_call_func_t func)
+{
+ csd->flags = 0;
+ csd->func = func;
+ csd->info = rq;
+}
#ifdef CONFIG_SCHED_HRTICK
/*
hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
HRTIMER_MODE_REL_PINNED_HARD);
}
+
#endif /* CONFIG_SMP */
static void hrtick_rq_init(struct rq *rq)
{
#ifdef CONFIG_SMP
- rq->hrtick_csd.flags = 0;
- rq->hrtick_csd.func = __hrtick_start;
- rq->hrtick_csd.info = rq;
+ rq_csd_init(rq, &rq->hrtick_csd, __hrtick_start);
#endif
-
hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
rq->hrtick_timer.function = hrtick;
}
wake_up_idle_cpu(cpu);
}
-static inline bool got_nohz_idle_kick(void)
+static void nohz_csd_func(void *info)
{
- int cpu = smp_processor_id();
-
- if (!(atomic_read(nohz_flags(cpu)) & NOHZ_KICK_MASK))
- return false;
-
- if (idle_cpu(cpu) && !need_resched())
- return true;
+ struct rq *rq = info;
+ int cpu = cpu_of(rq);
+ unsigned int flags;
/*
- * We can't run Idle Load Balance on this CPU for this time so we
- * cancel it and clear NOHZ_BALANCE_KICK
+ * Release the rq::nohz_csd.
*/
- atomic_andnot(NOHZ_KICK_MASK, nohz_flags(cpu));
- return false;
-}
+ flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(cpu));
+ WARN_ON(!(flags & NOHZ_KICK_MASK));
-#else /* CONFIG_NO_HZ_COMMON */
-
-static inline bool got_nohz_idle_kick(void)
-{
- return false;
+ rq->idle_balance = idle_cpu(cpu);
+ if (rq->idle_balance && !need_resched()) {
+ rq->nohz_idle_balance = flags;
+ raise_softirq_irqoff(SCHED_SOFTIRQ);
+ }
}
#endif /* CONFIG_NO_HZ_COMMON */
* __migrate_task() such that we will not miss enforcing cpus_ptr
* during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
*/
- sched_ttwu_pending();
+ flush_smp_call_function_from_idle();
raw_spin_lock(&p->pi_lock);
rq_lock(rq, &rf);
}
#ifdef CONFIG_SMP
-void sched_ttwu_pending(void)
+void sched_ttwu_pending(void *arg)
{
+ struct llist_node *llist = arg;
struct rq *rq = this_rq();
- struct llist_node *llist = llist_del_all(&rq->wake_list);
struct task_struct *p, *t;
struct rq_flags rf;
if (!llist)
return;
+ /*
+ * rq::ttwu_pending racy indication of out-standing wakeups.
+ * Races such that false-negatives are possible, since they
+ * are shorter lived that false-positives would be.
+ */
+ WRITE_ONCE(rq->ttwu_pending, 0);
+
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
rq_unlock_irqrestore(rq, &rf);
}
-void scheduler_ipi(void)
+void send_call_function_single_ipi(int cpu)
{
- /*
- * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
- * TIF_NEED_RESCHED remotely (for the first time) will also send
- * this IPI.
- */
- preempt_fold_need_resched();
-
- if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
- return;
-
- /*
- * Not all reschedule IPI handlers call irq_enter/irq_exit, since
- * traditionally all their work was done from the interrupt return
- * path. Now that we actually do some work, we need to make sure
- * we do call them.
- *
- * Some archs already do call them, luckily irq_enter/exit nest
- * properly.
- *
- * Arguably we should visit all archs and update all handlers,
- * however a fair share of IPIs are still resched only so this would
- * somewhat pessimize the simple resched case.
- */
- irq_enter();
- sched_ttwu_pending();
+ struct rq *rq = cpu_rq(cpu);
- /*
- * Check if someone kicked us for doing the nohz idle load balance.
- */
- if (unlikely(got_nohz_idle_kick())) {
- this_rq()->idle_balance = 1;
- raise_softirq_irqoff(SCHED_SOFTIRQ);
- }
- irq_exit();
+ if (!set_nr_if_polling(rq->idle))
+ arch_send_call_function_single_ipi(cpu);
+ else
+ trace_sched_wake_idle_without_ipi(cpu);
}
-static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
+/*
+ * Queue a task on the target CPUs wake_list and wake the CPU via IPI if
+ * necessary. The wakee CPU on receipt of the IPI will queue the task
+ * via sched_ttwu_wakeup() for activation so the wakee incurs the cost
+ * of the wakeup instead of the waker.
+ */
+static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
{
struct rq *rq = cpu_rq(cpu);
p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
- if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
- if (!set_nr_if_polling(rq->idle))
- smp_send_reschedule(cpu);
- else
- trace_sched_wake_idle_without_ipi(cpu);
- }
+ WRITE_ONCE(rq->ttwu_pending, 1);
+ __smp_call_single_queue(cpu, &p->wake_entry);
}
void wake_up_if_idle(int cpu)
{
return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
}
+
+static inline bool ttwu_queue_cond(int cpu, int wake_flags)
+{
+ /*
+ * If the CPU does not share cache, then queue the task on the
+ * remote rqs wakelist to avoid accessing remote data.
+ */
+ if (!cpus_share_cache(smp_processor_id(), cpu))
+ return true;
+
+ /*
+ * If the task is descheduling and the only running task on the
+ * CPU then use the wakelist to offload the task activation to
+ * the soon-to-be-idle CPU as the current CPU is likely busy.
+ * nr_running is checked to avoid unnecessary task stacking.
+ */
+ if ((wake_flags & WF_ON_RQ) && cpu_rq(cpu)->nr_running <= 1)
+ return true;
+
+ return false;
+}
+
+static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
+{
+ if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
+ sched_clock_cpu(cpu); /* Sync clocks across CPUs */
+ __ttwu_queue_wakelist(p, cpu, wake_flags);
+ return true;
+ }
+
+ return false;
+}
#endif /* CONFIG_SMP */
static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
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 across CPUs */
- ttwu_queue_remote(p, cpu, wake_flags);
+ if (ttwu_queue_wakelist(p, cpu, wake_flags))
return;
- }
#endif
rq_lock(rq, &rf);
if (p->on_rq && ttwu_remote(p, wake_flags))
goto unlock;
+ if (p->in_iowait) {
+ delayacct_blkio_end(p);
+ atomic_dec(&task_rq(p)->nr_iowait);
+ }
+
#ifdef CONFIG_SMP
+ p->sched_contributes_to_load = !!task_contributes_to_load(p);
+ p->state = TASK_WAKING;
+
/*
* Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
* possible to, falsely, observe p->on_cpu == 0.
/*
* If the owning (remote) CPU is still in the middle of schedule() with
+ * this task as prev, considering queueing p on the remote CPUs wake_list
+ * which potentially sends an IPI instead of spinning on p->on_cpu to
+ * let the waker make forward progress. This is safe because IRQs are
+ * disabled and the IPI will deliver after on_cpu is cleared.
+ */
+ if (READ_ONCE(p->on_cpu) && ttwu_queue_wakelist(p, cpu, wake_flags | WF_ON_RQ))
+ goto unlock;
+
+ /*
+ * 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_task().
*/
smp_cond_load_acquire(&p->on_cpu, !VAL);
- p->sched_contributes_to_load = !!task_contributes_to_load(p);
- p->state = TASK_WAKING;
-
- if (p->in_iowait) {
- delayacct_blkio_end(p);
- 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;
psi_ttwu_dequeue(p);
set_task_cpu(p, cpu);
}
-
-#else /* CONFIG_SMP */
-
- if (p->in_iowait) {
- delayacct_blkio_end(p);
- atomic_dec(&task_rq(p)->nr_iowait);
- }
-
#endif /* CONFIG_SMP */
ttwu_queue(p, cpu, wake_flags);
p->capture_control = NULL;
#endif
init_numa_balancing(clone_flags, p);
+#ifdef CONFIG_SMP
+ p->wake_entry_type = CSD_TYPE_TTWU;
+#endif
}
DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
schedstat_inc(this_rq()->sched_count);
}
+static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
+ struct rq_flags *rf)
+{
+#ifdef CONFIG_SMP
+ const struct sched_class *class;
+ /*
+ * We must do the balancing pass before put_prev_task(), such
+ * that when we release the rq->lock the task is in the same
+ * state as before we took rq->lock.
+ *
+ * We can terminate the balance pass as soon as we know there is
+ * a runnable task of @class priority or higher.
+ */
+ for_class_range(class, prev->sched_class, &idle_sched_class) {
+ if (class->balance(rq, prev, rf))
+ break;
+ }
+#endif
+
+ put_prev_task(rq, prev);
+}
+
/*
* Pick up the highest-prio task:
*/
}
restart:
-#ifdef CONFIG_SMP
- /*
- * We must do the balancing pass before put_next_task(), such
- * that when we release the rq->lock the task is in the same
- * state as before we took rq->lock.
- *
- * We can terminate the balance pass as soon as we know there is
- * a runnable task of @class priority or higher.
- */
- for_class_range(class, prev->sched_class, &idle_sched_class) {
- if (class->balance(rq, prev, rf))
- break;
- }
-#endif
-
- put_prev_task(rq, prev);
+ put_prev_task_balance(rq, prev, rf);
for_each_class(class) {
p = class->pick_next_task(rq);
return 0;
#ifdef CONFIG_SMP
- if (!llist_empty(&rq->wake_list))
+ if (rq->ttwu_pending)
return 0;
#endif
struct mm_struct *mm = current->active_mm;
BUG_ON(cpu_online(smp_processor_id()));
+ BUG_ON(current != this_rq()->idle);
if (mm != &init_mm) {
switch_mm(mm, &init_mm, current);
- current->active_mm = &init_mm;
finish_arch_post_lock_switch();
}
- mmdrop(mm);
+
+ /* finish_cpu(), as ran on the BP, will clean up the active_mm state */
}
/*
struct rq_flags rf;
/* Handle pending wakeups and then migrate everything off */
- sched_ttwu_pending();
sched_tick_stop(cpu);
rq_lock_irqsave(rq, &rf);
root_task_group.cfs_rq = (struct cfs_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
+ root_task_group.shares = ROOT_TASK_GROUP_LOAD;
+ init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
root_task_group.rt_se = (struct sched_rt_entity **)ptr;
init_rt_rq(&rq->rt);
init_dl_rq(&rq->dl);
#ifdef CONFIG_FAIR_GROUP_SCHED
- root_task_group.shares = ROOT_TASK_GROUP_LOAD;
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
/*
* 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 */
#ifdef CONFIG_NO_HZ_COMMON
rq->last_blocked_load_update_tick = jiffies;
atomic_set(&rq->nohz_flags, 0);
+
+ rq_csd_init(rq, &rq->nohz_csd, nohz_csd_func);
#endif
#endif /* CONFIG_SMP */
hrtick_rq_init(rq);
const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
+/* More than 203 days if BW_SHIFT equals 20. */
+static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC;
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
return -EINVAL;
/*
+ * Bound quota to defend quota against overflow during bandwidth shift.
+ */
+ if (quota != RUNTIME_INF && quota > max_cfs_runtime)
+ return -EINVAL;
+
+ /*
* Prevent race between setting of cfs_rq->runtime_enabled and
* unthrottle_offline_cfs_rqs().
*/
* Based on the work by Paul Menage (menage@google.com) and Balbir Singh
* (balbir@in.ibm.com).
*/
+#include <asm/irq_regs.h>
#include "sched.h"
/* Time spent by the tasks of the CPU accounting group executing in ... */
{
struct cpuacct *ca;
int index = CPUACCT_STAT_SYSTEM;
- struct pt_regs *regs = task_pt_regs(tsk);
+ struct pt_regs *regs = get_irq_regs() ? : task_pt_regs(tsk);
if (regs && user_mode(regs))
index = CPUACCT_STAT_USER;
rcu_read_lock();
for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
- this_cpu_ptr(ca->cpuusage)->usages[index] += cputime;
+ __this_cpu_add(ca->cpuusage->usages[index], cputime);
rcu_read_unlock();
}
rcu_read_lock();
for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
- this_cpu_ptr(ca->cpustat)->cpustat[index] += val;
+ __this_cpu_add(ca->cpustat->cpustat[index], val);
rcu_read_unlock();
}
set_table_entry(&table[2], "busy_factor", &sd->busy_factor, sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[3], "imbalance_pct", &sd->imbalance_pct, sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[4], "cache_nice_tries", &sd->cache_nice_tries, sizeof(int), 0644, proc_dointvec_minmax);
- set_table_entry(&table[5], "flags", &sd->flags, sizeof(int), 0644, proc_dointvec_minmax);
+ set_table_entry(&table[5], "flags", &sd->flags, sizeof(int), 0444, proc_dointvec_minmax);
set_table_entry(&table[6], "max_newidle_lb_cost", &sd->max_newidle_lb_cost, sizeof(long), 0644, proc_doulongvec_minmax);
set_table_entry(&table[7], "name", sd->name, CORENAME_MAX_SIZE, 0444, proc_dostring);
/* &table[8] is terminator */
else
SEQ_printf(m, " %c", task_state_to_char(p));
- SEQ_printf(m, "%15s %5d %9Ld.%06ld %9Ld %5d ",
+ SEQ_printf(m, " %15s %5d %9Ld.%06ld %9Ld %5d ",
p->comm, task_pid_nr(p),
SPLIT_NS(p->se.vruntime),
(long long)(p->nvcsw + p->nivcsw),
SEQ_printf(m, "\n");
SEQ_printf(m, "runnable tasks:\n");
- SEQ_printf(m, " S task PID tree-key switches prio"
+ SEQ_printf(m, " S task PID tree-key switches prio"
" wait-time sum-exec sum-sleep\n");
SEQ_printf(m, "-------------------------------------------------------"
- "----------------------------------------------------\n");
+ "------------------------------------------------------\n");
rcu_read_lock();
for_each_process_thread(g, p) {
P(nr_running);
P(nr_switches);
- P(nr_load_updates);
P(nr_uninterruptible);
PN(next_balance);
SEQ_printf(m, " .%-30s: %ld\n", "curr->pid", (long)(task_pid_nr(rq->curr)));
#undef SET_SYSCTL
}
-void sched_init_granularity(void)
+void __init sched_init_granularity(void)
{
update_sysctl();
}
* more by CPU use than by memory faults.
*/
unsigned long *faults_cpu;
- unsigned long faults[0];
+ unsigned long faults[];
};
/*
update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
long delta = gcfs_rq->avg.util_avg - se->avg.util_avg;
+ /*
+ * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+ * See ___update_load_avg() for details.
+ */
+ u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
/* Nothing to update */
if (!delta)
return;
- /*
- * The relation between sum and avg is:
- *
- * LOAD_AVG_MAX - 1024 + sa->period_contrib
- *
- * however, the PELT windows are not aligned between grq and gse.
- */
-
/* Set new sched_entity's utilization */
se->avg.util_avg = gcfs_rq->avg.util_avg;
- se->avg.util_sum = se->avg.util_avg * LOAD_AVG_MAX;
+ se->avg.util_sum = se->avg.util_avg * divider;
/* Update parent cfs_rq utilization */
add_positive(&cfs_rq->avg.util_avg, delta);
- cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX;
+ cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * divider;
}
static inline void
update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
long delta = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
+ /*
+ * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+ * See ___update_load_avg() for details.
+ */
+ u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
/* Nothing to update */
if (!delta)
return;
- /*
- * The relation between sum and avg is:
- *
- * LOAD_AVG_MAX - 1024 + sa->period_contrib
- *
- * however, the PELT windows are not aligned between grq and gse.
- */
-
/* Set new sched_entity's runnable */
se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
- se->avg.runnable_sum = se->avg.runnable_avg * LOAD_AVG_MAX;
+ se->avg.runnable_sum = se->avg.runnable_avg * divider;
/* Update parent cfs_rq runnable */
add_positive(&cfs_rq->avg.runnable_avg, delta);
- cfs_rq->avg.runnable_sum = cfs_rq->avg.runnable_avg * LOAD_AVG_MAX;
+ cfs_rq->avg.runnable_sum = cfs_rq->avg.runnable_avg * divider;
}
static inline void
unsigned long load_avg;
u64 load_sum = 0;
s64 delta_sum;
+ u32 divider;
if (!runnable_sum)
return;
gcfs_rq->prop_runnable_sum = 0;
+ /*
+ * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+ * See ___update_load_avg() for details.
+ */
+ divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+
if (runnable_sum >= 0) {
/*
* Add runnable; clip at LOAD_AVG_MAX. Reflects that until
* the CPU is saturated running == runnable.
*/
runnable_sum += se->avg.load_sum;
- runnable_sum = min(runnable_sum, (long)LOAD_AVG_MAX);
+ runnable_sum = min_t(long, runnable_sum, divider);
} else {
/*
* Estimate the new unweighted runnable_sum of the gcfs_rq by
runnable_sum = max(runnable_sum, running_sum);
load_sum = (s64)se_weight(se) * runnable_sum;
- load_avg = div_s64(load_sum, LOAD_AVG_MAX);
+ load_avg = div_s64(load_sum, divider);
delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
delta_avg = load_avg - se->avg.load_avg;
*/
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
+ /*
+ * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+ * See ___update_load_avg() for details.
+ */
u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
/*
return cfs_rq->avg.load_avg;
}
+static int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
+
static inline unsigned long task_util(struct task_struct *p)
{
return READ_ONCE(p->se.avg.util_avg);
static inline void
detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
-static inline int idle_balance(struct rq *rq, struct rq_flags *rf)
+static inline int newidle_balance(struct rq *rq, struct rq_flags *rf)
{
return 0;
}
}
/* returns 0 on failure to allocate runtime */
-static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
+ struct cfs_rq *cfs_rq, u64 target_runtime)
{
- struct task_group *tg = cfs_rq->tg;
- struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
- u64 amount = 0, min_amount;
+ u64 min_amount, amount = 0;
+
+ lockdep_assert_held(&cfs_b->lock);
/* note: this is a positive sum as runtime_remaining <= 0 */
- min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
+ min_amount = target_runtime - cfs_rq->runtime_remaining;
- raw_spin_lock(&cfs_b->lock);
if (cfs_b->quota == RUNTIME_INF)
amount = min_amount;
else {
cfs_b->idle = 0;
}
}
- raw_spin_unlock(&cfs_b->lock);
cfs_rq->runtime_remaining += amount;
return cfs_rq->runtime_remaining > 0;
}
+/* returns 0 on failure to allocate runtime */
+static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+ int ret;
+
+ raw_spin_lock(&cfs_b->lock);
+ ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
+ raw_spin_unlock(&cfs_b->lock);
+
+ return ret;
+}
+
static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
{
/* dock delta_exec before expiring quota (as it could span periods) */
return 0;
}
-static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
+static bool 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, idle_task_delta, dequeue = 1;
- bool empty;
+
+ raw_spin_lock(&cfs_b->lock);
+ /* This will start the period timer if necessary */
+ if (__assign_cfs_rq_runtime(cfs_b, cfs_rq, 1)) {
+ /*
+ * We have raced with bandwidth becoming available, and if we
+ * actually throttled the timer might not unthrottle us for an
+ * entire period. We additionally needed to make sure that any
+ * subsequent check_cfs_rq_runtime calls agree not to throttle
+ * us, as we may commit to do cfs put_prev+pick_next, so we ask
+ * for 1ns of runtime rather than just check cfs_b.
+ */
+ dequeue = 0;
+ } else {
+ list_add_tail_rcu(&cfs_rq->throttled_list,
+ &cfs_b->throttled_cfs_rq);
+ }
+ raw_spin_unlock(&cfs_b->lock);
+
+ if (!dequeue)
+ return false; /* Throttle no longer required. */
se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
if (!se)
sub_nr_running(rq, task_delta);
- cfs_rq->throttled = 1;
- cfs_rq->throttled_clock = rq_clock(rq);
- raw_spin_lock(&cfs_b->lock);
- empty = list_empty(&cfs_b->throttled_cfs_rq);
-
/*
- * Add to the _head_ of the list, so that an already-started
- * distribute_cfs_runtime will not see us. If disribute_cfs_runtime is
- * not running add to the tail so that later runqueues don't get starved.
+ * Note: distribution will already see us throttled via the
+ * throttled-list. rq->lock protects completion.
*/
- if (cfs_b->distribute_running)
- list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
- else
- list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
-
- /*
- * If we're the first throttled task, make sure the bandwidth
- * timer is running.
- */
- if (empty)
- start_cfs_bandwidth(cfs_b);
-
- raw_spin_unlock(&cfs_b->lock);
+ cfs_rq->throttled = 1;
+ cfs_rq->throttled_clock = rq_clock(rq);
+ return true;
}
void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
/*
* This check is repeated as we release cfs_b->lock while we unthrottle.
*/
- while (throttled && cfs_b->runtime > 0 && !cfs_b->distribute_running) {
- cfs_b->distribute_running = 1;
+ while (throttled && cfs_b->runtime > 0) {
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
/* we can't nest cfs_b->lock while distributing bandwidth */
distribute_cfs_runtime(cfs_b);
raw_spin_lock_irqsave(&cfs_b->lock, flags);
- cfs_b->distribute_running = 0;
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
}
/* confirm we're still not at a refresh boundary */
raw_spin_lock_irqsave(&cfs_b->lock, flags);
cfs_b->slack_started = false;
- if (cfs_b->distribute_running) {
- raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
- return;
- }
if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
runtime = cfs_b->runtime;
- if (runtime)
- cfs_b->distribute_running = 1;
-
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
if (!runtime)
distribute_cfs_runtime(cfs_b);
raw_spin_lock_irqsave(&cfs_b->lock, flags);
- cfs_b->distribute_running = 0;
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
}
if (cfs_rq_throttled(cfs_rq))
return true;
- throttle_cfs_rq(cfs_rq);
- return true;
+ return throttle_cfs_rq(cfs_rq);
}
static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
if (!overrun)
break;
+ idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
+
if (++count > 3) {
u64 new, old = ktime_to_ns(cfs_b->period);
/* reset count so we don't come right back in here */
count = 0;
}
-
- idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
}
if (idle)
cfs_b->period_active = 0;
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;
- cfs_b->distribute_running = 0;
cfs_b->slack_started = false;
}
list_add_leaf_cfs_rq(cfs_rq);
}
-enqueue_throttle:
- if (!se) {
- add_nr_running(rq, 1);
- /*
- * Since new tasks are assigned an initial util_avg equal to
- * half of the spare capacity of their CPU, tiny tasks have the
- * ability to cross the overutilized threshold, which will
- * result in the load balancer ruining all the task placement
- * done by EAS. As a way to mitigate that effect, do not account
- * for the first enqueue operation of new tasks during the
- * overutilized flag detection.
- *
- * A better way of solving this problem would be to wait for
- * the PELT signals of tasks to converge before taking them
- * into account, but that is not straightforward to implement,
- * and the following generally works well enough in practice.
- */
- if (flags & ENQUEUE_WAKEUP)
- update_overutilized_status(rq);
+ /* At this point se is NULL and we are at root level*/
+ add_nr_running(rq, 1);
- }
+ /*
+ * Since new tasks are assigned an initial util_avg equal to
+ * half of the spare capacity of their CPU, tiny tasks have the
+ * ability to cross the overutilized threshold, which will
+ * result in the load balancer ruining all the task placement
+ * done by EAS. As a way to mitigate that effect, do not account
+ * for the first enqueue operation of new tasks during the
+ * overutilized flag detection.
+ *
+ * A better way of solving this problem would be to wait for
+ * the PELT signals of tasks to converge before taking them
+ * into account, but that is not straightforward to implement,
+ * and the following generally works well enough in practice.
+ */
+ if (flags & ENQUEUE_WAKEUP)
+ update_overutilized_status(rq);
+enqueue_throttle:
if (cfs_bandwidth_used()) {
/*
* When bandwidth control is enabled; the cfs_rq_throttled()
{
unsigned int master = current->wakee_flips;
unsigned int slave = p->wakee_flips;
- int factor = this_cpu_read(sd_llc_size);
+ int factor = __this_cpu_read(sd_llc_size);
if (master < slave)
swap(master, slave);
}
static struct sched_group *
-find_idlest_group(struct sched_domain *sd, struct task_struct *p,
- int this_cpu, int sd_flag);
+find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
/*
* find_idlest_group_cpu - find the idlest CPU among the CPUs in the group.
continue;
}
- group = find_idlest_group(sd, p, cpu, sd_flag);
+ group = find_idlest_group(sd, p, cpu);
if (!group) {
sd = sd->child;
continue;
rcu_read_lock();
for_each_domain(cpu, tmp) {
- if (!(tmp->flags & SD_LOAD_BALANCE))
- break;
-
/*
* If both 'cpu' and 'prev_cpu' are part of this domain,
* cpu is a valid SD_WAKE_AFFINE target.
*/
#ifdef CONFIG_SMP
- if (!llist_empty(&rq->wake_list))
+ if (rq->ttwu_pending)
return 0;
#endif
* Assumes p is allowed on at least one CPU in sd.
*/
static struct sched_group *
-find_idlest_group(struct sched_domain *sd, struct task_struct *p,
- int this_cpu, int sd_flag)
+find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
{
struct sched_group *idlest = NULL, *local = NULL, *group = sd->groups;
struct sg_lb_stats local_sgs, tmp_sgs;
static int should_we_balance(struct lb_env *env)
{
struct sched_group *sg = env->sd->groups;
- int cpu, balance_cpu = -1;
+ int cpu;
/*
* Ensure the balancing environment is consistent; can happen
if (!idle_cpu(cpu))
continue;
- balance_cpu = cpu;
- break;
+ /* Are we the first idle CPU? */
+ return cpu == env->dst_cpu;
}
- if (balance_cpu == -1)
- balance_cpu = group_balance_cpu(sg);
-
- /*
- * First idle CPU or the first CPU(busiest) in this sched group
- * is eligible for doing load balancing at this and above domains.
- */
- return balance_cpu == env->dst_cpu;
+ /* Are we the first CPU of this group ? */
+ return group_balance_cpu(sg) == env->dst_cpu;
}
/*
/* Search for an sd spanning us and the target CPU. */
rcu_read_lock();
for_each_domain(target_cpu, sd) {
- if ((sd->flags & SD_LOAD_BALANCE) &&
- cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
- break;
+ if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
+ break;
}
if (likely(sd)) {
}
max_cost += sd->max_newidle_lb_cost;
- if (!(sd->flags & SD_LOAD_BALANCE))
- continue;
-
/*
* Stop the load balance at this level. There is another
* CPU in our sched group which is doing load balancing more
if (ilb_cpu >= nr_cpu_ids)
return;
+ /*
+ * Access to rq::nohz_csd is serialized by NOHZ_KICK_MASK; he who sets
+ * the first flag owns it; cleared by nohz_csd_func().
+ */
flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
if (flags & NOHZ_KICK_MASK)
return;
/*
- * Use smp_send_reschedule() instead of resched_cpu().
- * This way we generate a sched IPI on the target CPU which
+ * This way we generate an 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);
+ smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
}
/*
*/
static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
{
- int this_cpu = this_rq->cpu;
- unsigned int flags;
+ unsigned int flags = this_rq->nohz_idle_balance;
- if (!(atomic_read(nohz_flags(this_cpu)) & NOHZ_KICK_MASK))
+ if (!flags)
return false;
- if (idle != CPU_IDLE) {
- atomic_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu));
- return false;
- }
+ this_rq->nohz_idle_balance = 0;
- /* could be _relaxed() */
- flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu));
- if (!(flags & NOHZ_KICK_MASK))
+ if (idle != CPU_IDLE)
return false;
_nohz_idle_balance(this_rq, flags, idle);
* 0 - failed, no new tasks
* > 0 - success, new (fair) tasks present
*/
-int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
+static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
{
unsigned long next_balance = jiffies + HZ;
int this_cpu = this_rq->cpu;
int continue_balancing = 1;
u64 t0, domain_cost;
- if (!(sd->flags & SD_LOAD_BALANCE))
- continue;
-
if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
update_next_balance(sd, &next_balance);
break;
*/
smp_mb__after_atomic();
- sched_ttwu_pending();
+ /*
+ * RCU relies on this call to be done outside of an RCU read-side
+ * critical section.
+ */
+ flush_smp_call_function_from_idle();
schedule_idle();
if (unlikely(klp_patch_pending(current)))
return 1;
}
+/*
+ * When syncing *_avg with *_sum, we must take into account the current
+ * position in the PELT segment otherwise the remaining part of the segment
+ * will be considered as idle time whereas it's not yet elapsed and this will
+ * generate unwanted oscillation in the range [1002..1024[.
+ *
+ * The max value of *_sum varies with the position in the time segment and is
+ * equals to :
+ *
+ * LOAD_AVG_MAX*y + sa->period_contrib
+ *
+ * which can be simplified into:
+ *
+ * LOAD_AVG_MAX - 1024 + sa->period_contrib
+ *
+ * because LOAD_AVG_MAX*y == LOAD_AVG_MAX-1024
+ *
+ * The same care must be taken when a sched entity is added, updated or
+ * removed from a cfs_rq and we need to update sched_avg. Scheduler entities
+ * and the cfs rq, to which they are attached, have the same position in the
+ * time segment because they use the same clock. This means that we can use
+ * the period_contrib of cfs_rq when updating the sched_avg of a sched_entity
+ * if it's more convenient.
+ */
static __always_inline void
___update_load_avg(struct sched_avg *sa, unsigned long load)
{
int sched_rr_timeslice = RR_TIMESLICE;
int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
+/* More than 4 hours if BW_SHIFT equals 20. */
+static const u64 max_rt_runtime = MAX_BW;
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
if (rt_period == 0)
return -EINVAL;
+ /*
+ * Bound quota to defend quota against overflow during bandwidth shift.
+ */
+ if (rt_runtime != RUNTIME_INF && rt_runtime > max_rt_runtime)
+ return -EINVAL;
+
mutex_lock(&rt_constraints_mutex);
err = __rt_schedulable(tg, rt_period, rt_runtime);
if (err)
return -EINVAL;
if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
- (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
+ ((sysctl_sched_rt_runtime > sysctl_sched_rt_period) ||
+ ((u64)sysctl_sched_rt_runtime *
+ NSEC_PER_USEC > max_rt_runtime)))
return -EINVAL;
return 0;
u8 idle;
u8 period_active;
- u8 distribute_running;
u8 slack_started;
struct hrtimer period_timer;
struct hrtimer slack_timer;
#ifdef CONFIG_SMP
unsigned long last_blocked_load_update_tick;
unsigned int has_blocked_load;
+ call_single_data_t nohz_csd;
#endif /* CONFIG_SMP */
unsigned int nohz_tick_stopped;
- atomic_t nohz_flags;
+ atomic_t nohz_flags;
#endif /* CONFIG_NO_HZ_COMMON */
- unsigned long nr_load_updates;
+#ifdef CONFIG_SMP
+ unsigned int ttwu_pending;
+#endif
u64 nr_switches;
#ifdef CONFIG_UCLAMP_TASK
struct callback_head *balance_callback;
+ unsigned char nohz_idle_balance;
unsigned char idle_balance;
unsigned long misfit_task_load;
/* This is used to determine avg_idle's max value */
u64 max_idle_balance_cost;
-#endif
+#endif /* CONFIG_SMP */
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
u64 prev_irq_time;
unsigned int ttwu_local;
#endif
-#ifdef CONFIG_SMP
- struct llist_head wake_list;
-#endif
-
#ifdef CONFIG_CPU_IDLE
/* Must be inspected within a rcu lock section */
struct cpuidle_state *idle_state;
rq->balance_callback = head;
}
-extern void sched_ttwu_pending(void);
-
#define rcu_dereference_check_sched_domain(p) \
rcu_dereference_check((p), \
lockdep_is_held(&sched_domains_mutex))
* by attaching extra space to the end of the structure,
* depending on how many CPUs the kernel has booted up with)
*/
- unsigned long cpumask[0];
+ unsigned long cpumask[];
};
static inline struct cpumask *sched_group_span(struct sched_group *sg)
}
#endif
-extern int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
-
-#else
-
-static inline void sched_ttwu_pending(void) { }
+extern void flush_smp_call_function_from_idle(void);
-static inline int newidle_balance(struct rq *this_rq, struct rq_flags *rf) { return 0; }
-
-#endif /* CONFIG_SMP */
+#else /* !CONFIG_SMP: */
+static inline void flush_smp_call_function_from_idle(void) { }
+#endif
#include "stats.h"
#include "autogroup.h"
*/
#define WF_SYNC 0x01 /* Waker goes to sleep after wakeup */
#define WF_FORK 0x02 /* Child wakeup after fork */
-#define WF_MIGRATED 0x4 /* Internal use, task got migrated */
+#define WF_MIGRATED 0x04 /* Internal use, task got migrated */
+#define WF_ON_RQ 0x08 /* Wakee is on_rq */
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution
#define BW_SHIFT 20
#define BW_UNIT (1 << BW_SHIFT)
#define RATIO_SHIFT 8
+#define MAX_BW_BITS (64 - BW_SHIFT)
+#define MAX_BW ((1ULL << MAX_BW_BITS) - 1)
unsigned long to_ratio(u64 period, u64 runtime);
extern void init_entity_runnable_average(struct sched_entity *se);
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Scheduler internal SMP callback types and methods between the scheduler
+ * and other internal parts of the core kernel:
+ */
+
+extern void sched_ttwu_pending(void *arg);
+
+extern void send_call_function_single_ipi(int cpu);
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);
return 1;
/* Following flags need at least 2 groups */
- if (sd->flags & (SD_LOAD_BALANCE |
- SD_BALANCE_NEWIDLE |
+ if (sd->flags & (SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
SD_SHARE_CPUCAPACITY |
/* 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);
+ pflags &= ~(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;
}
.cache_nice_tries = 0,
- .flags = 1*SD_LOAD_BALANCE
- | 1*SD_BALANCE_NEWIDLE
+ .flags = 1*SD_BALANCE_NEWIDLE
| 1*SD_BALANCE_EXEC
| 1*SD_BALANCE_FORK
| 0*SD_BALANCE_WAKE
#include <linux/hypervisor.h>
#include "smpboot.h"
+#include "sched/smp.h"
-enum {
- CSD_FLAG_LOCK = 0x01,
- CSD_FLAG_SYNCHRONOUS = 0x02,
-};
+#define CSD_TYPE(_csd) ((_csd)->flags & CSD_FLAG_TYPE_MASK)
struct call_function_data {
call_single_data_t __percpu *csd;
* still pending.
*/
flush_smp_call_function_queue(false);
+ irq_work_run();
return 0;
}
static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
+void __smp_call_single_queue(int cpu, struct llist_node *node)
+{
+ /*
+ * The list addition should be visible before sending the IPI
+ * handler locks the list to pull the entry off it because of
+ * normal cache coherency rules implied by spinlocks.
+ *
+ * If IPIs can go out of order to the cache coherency protocol
+ * in an architecture, sufficient synchronisation should be added
+ * to arch code to make it appear to obey cache coherency WRT
+ * locking and barrier primitives. Generic code isn't really
+ * equipped to do the right thing...
+ */
+ if (llist_add(node, &per_cpu(call_single_queue, cpu)))
+ send_call_function_single_ipi(cpu);
+}
+
/*
* Insert a previously allocated call_single_data_t element
* for execution on the given CPU. data must already have
* ->func, ->info, and ->flags set.
*/
-static int generic_exec_single(int cpu, call_single_data_t *csd,
- smp_call_func_t func, void *info)
+static int generic_exec_single(int cpu, call_single_data_t *csd)
{
if (cpu == smp_processor_id()) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
unsigned long flags;
/*
return 0;
}
-
if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
csd_unlock(csd);
return -ENXIO;
}
- csd->func = func;
- csd->info = info;
-
- /*
- * The list addition should be visible before sending the IPI
- * handler locks the list to pull the entry off it because of
- * normal cache coherency rules implied by spinlocks.
- *
- * If IPIs can go out of order to the cache coherency protocol
- * in an architecture, sufficient synchronisation should be added
- * to arch code to make it appear to obey cache coherency WRT
- * locking and barrier primitives. Generic code isn't really
- * equipped to do the right thing...
- */
- if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
- arch_send_call_function_single_ipi(cpu);
+ __smp_call_single_queue(cpu, &csd->llist);
return 0;
}
*/
static void flush_smp_call_function_queue(bool warn_cpu_offline)
{
- struct llist_head *head;
- struct llist_node *entry;
call_single_data_t *csd, *csd_next;
+ struct llist_node *entry, *prev;
+ struct llist_head *head;
static bool warned;
lockdep_assert_irqs_disabled();
* We don't have to use the _safe() variant here
* because we are not invoking the IPI handlers yet.
*/
- llist_for_each_entry(csd, entry, llist)
- pr_warn("IPI callback %pS sent to offline CPU\n",
- csd->func);
+ llist_for_each_entry(csd, entry, llist) {
+ switch (CSD_TYPE(csd)) {
+ case CSD_TYPE_ASYNC:
+ case CSD_TYPE_SYNC:
+ case CSD_TYPE_IRQ_WORK:
+ pr_warn("IPI callback %pS sent to offline CPU\n",
+ csd->func);
+ break;
+
+ case CSD_TYPE_TTWU:
+ pr_warn("IPI task-wakeup sent to offline CPU\n");
+ break;
+
+ default:
+ pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
+ CSD_TYPE(csd));
+ break;
+ }
+ }
}
+ /*
+ * First; run all SYNC callbacks, people are waiting for us.
+ */
+ prev = NULL;
llist_for_each_entry_safe(csd, csd_next, entry, llist) {
- smp_call_func_t func = csd->func;
- void *info = csd->info;
-
/* Do we wait until *after* callback? */
- if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
+ if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
+
+ if (prev) {
+ prev->next = &csd_next->llist;
+ } else {
+ entry = &csd_next->llist;
+ }
+
func(info);
csd_unlock(csd);
} else {
- csd_unlock(csd);
- func(info);
+ prev = &csd->llist;
}
}
+ if (!entry)
+ return;
+
/*
- * Handle irq works queued remotely by irq_work_queue_on().
- * Smp functions above are typically synchronous so they
- * better run first since some other CPUs may be busy waiting
- * for them.
+ * Second; run all !SYNC callbacks.
*/
- irq_work_run();
+ prev = NULL;
+ llist_for_each_entry_safe(csd, csd_next, entry, llist) {
+ int type = CSD_TYPE(csd);
+
+ if (type != CSD_TYPE_TTWU) {
+ if (prev) {
+ prev->next = &csd_next->llist;
+ } else {
+ entry = &csd_next->llist;
+ }
+
+ if (type == CSD_TYPE_ASYNC) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
+
+ csd_unlock(csd);
+ func(info);
+ } else if (type == CSD_TYPE_IRQ_WORK) {
+ irq_work_single(csd);
+ }
+
+ } else {
+ prev = &csd->llist;
+ }
+ }
+
+ /*
+ * Third; only CSD_TYPE_TTWU is left, issue those.
+ */
+ if (entry)
+ sched_ttwu_pending(entry);
+}
+
+void flush_smp_call_function_from_idle(void)
+{
+ unsigned long flags;
+
+ if (llist_empty(this_cpu_ptr(&call_single_queue)))
+ return;
+
+ local_irq_save(flags);
+ flush_smp_call_function_queue(true);
+ local_irq_restore(flags);
}
/*
{
call_single_data_t *csd;
call_single_data_t csd_stack = {
- .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
+ .flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC,
};
int this_cpu;
int err;
csd_lock(csd);
}
- err = generic_exec_single(cpu, csd, func, info);
+ csd->func = func;
+ csd->info = info;
+
+ err = generic_exec_single(cpu, csd);
if (wait)
csd_lock_wait(csd);
csd->flags = CSD_FLAG_LOCK;
smp_wmb();
- err = generic_exec_single(cpu, csd, csd->func, csd->info);
+ err = generic_exec_single(cpu, csd);
out:
preempt_enable();
csd_lock(csd);
if (wait)
- csd->flags |= CSD_FLAG_SYNCHRONOUS;
+ csd->flags |= CSD_TYPE_SYNC;
csd->func = func;
csd->info = info;
if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
{
int num_nodes, num_cpus;
+ /*
+ * Ensure struct irq_work layout matches so that
+ * flush_smp_call_function_queue() can do horrible things.
+ */
+ BUILD_BUG_ON(offsetof(struct irq_work, llnode) !=
+ offsetof(struct __call_single_data, llist));
+ BUILD_BUG_ON(offsetof(struct irq_work, func) !=
+ offsetof(struct __call_single_data, func));
+ BUILD_BUG_ON(offsetof(struct irq_work, flags) !=
+ offsetof(struct __call_single_data, flags));
+
+ /*
+ * Assert the CSD_TYPE_TTWU layout is similar enough
+ * for task_struct to be on the @call_single_queue.
+ */
+ BUILD_BUG_ON(offsetof(struct task_struct, wake_entry_type) - offsetof(struct task_struct, wake_entry) !=
+ offsetof(struct __call_single_data, flags) - offsetof(struct __call_single_data, llist));
+
idle_threads_init();
cpuhp_threads_init();
OSDN Git Service
