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Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse Source 
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - tickless load average calculation enhancements (Byungchul Park)

   - vtime handling enhancements (Frederic Weisbecker)

   - scalability improvement via properly aligning a key structure field
     (Jiri Olsa)

   - various stop_machine() fixes (Oleg Nesterov)

   - sched/numa enhancement (Rik van Riel)

   - various fixes and improvements (Andi Kleen, Dietmar Eggemann,
     Geliang Tang, Hiroshi Shimamoto, Joonwoo Park, Peter Zijlstra,
     Waiman Long, Wanpeng Li, Yuyang Du)"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
  sched/fair: Fix new task's load avg removed from source CPU in wake_up_new_task()
  sched/core: Move sched_entity::avg into separate cache line
  x86/fpu: Properly align size in CHECK_MEMBER_AT_END_OF() macro
  sched/deadline: Fix the earliest_dl.next logic
  sched/fair: Disable the task group load_avg update for the root_task_group
  sched/fair: Move the cache-hot 'load_avg' variable into its own cacheline
  sched/fair: Avoid redundant idle_cpu() call in update_sg_lb_stats()
  sched/core: Move the sched_to_prio[] arrays out of line
  sched/cputime: Convert vtime_seqlock to seqcount
  sched/cputime: Introduce vtime accounting check for readers
  sched/cputime: Rename vtime_accounting_enabled() to vtime_accounting_cpu_enabled()
  sched/cputime: Correctly handle task guest time on housekeepers
  sched/cputime: Clarify vtime symbols and document them
  sched/cputime: Remove extra cost in task_cputime()
  sched/fair: Make it possible to account fair load avg consistently
  sched/fair: Modify the comment about lock assumptions in migrate_task_rq_fair()
  stop_machine: Clean up the usage of the preemption counter in cpu_stopper_thread()
  stop_machine: Shift the 'done != NULL' check from cpu_stop_signal_done() to callers
  stop_machine: Kill cpu_stop_done->executed
  stop_machine: Change __stop_cpus() to rely on cpu_stop_queue_work()
  ...
This commit is contained in:
Linus Torvalds
2016-01-11 15:13:38 -08:00
parent 4bd20db2c0 0905f04eb2
commit af345201ea
17 changed files with 487 additions and 308 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/sched/auto_group.c
View File

@@ -212,7 +212,7 @@ int proc_sched_autogroup_set_nice(struct task_struct *p, int nice)
ag = autogroup_task_get(p);
down_write(&ag->lock);
err = sched_group_set_shares(ag->tg, prio_to_weight[nice + 20]);
err = sched_group_set_shares(ag->tg, sched_prio_to_weight[nice + 20]);
if (!err)
ag->nice = nice;
up_write(&ag->lock);

76
kernel/sched/core.c
View File

@@ -731,7 +731,7 @@ bool sched_can_stop_tick(void)
if (current->policy == SCHED_RR) {
struct sched_rt_entity *rt_se = &current->rt;
return rt_se->run_list.prev == rt_se->run_list.next;
return list_is_singular(&rt_se->run_list);
}
/*
@@ -823,8 +823,8 @@ static void set_load_weight(struct task_struct *p)
return;
}
load->weight = scale_load(prio_to_weight[prio]);
load->inv_weight = prio_to_wmult[prio];
load->weight = scale_load(sched_prio_to_weight[prio]);
load->inv_weight = sched_prio_to_wmult[prio];
}
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
@@ -1071,8 +1071,8 @@ static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new
{
lockdep_assert_held(&rq->lock);
dequeue_task(rq, p, 0);
p->on_rq = TASK_ON_RQ_MIGRATING;
dequeue_task(rq, p, 0);
set_task_cpu(p, new_cpu);
raw_spin_unlock(&rq->lock);
@@ -1080,8 +1080,8 @@ static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new
raw_spin_lock(&rq->lock);
BUG_ON(task_cpu(p) != new_cpu);
p->on_rq = TASK_ON_RQ_QUEUED;
enqueue_task(rq, p, 0);
p->on_rq = TASK_ON_RQ_QUEUED;
check_preempt_curr(rq, p, 0);
return rq;
@@ -1274,6 +1274,15 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
!p->on_rq);
/*
* Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
* because schedstat_wait_{start,end} rebase migrating task's wait_start
* time relying on p->on_rq.
*/
WARN_ON_ONCE(p->state == TASK_RUNNING &&
p->sched_class == &fair_sched_class &&
(p->on_rq && !task_on_rq_migrating(p)));
#ifdef CONFIG_LOCKDEP
/*
* The caller should hold either p->pi_lock or rq->lock, when changing
@@ -1310,9 +1319,11 @@ static void __migrate_swap_task(struct task_struct *p, int cpu)
src_rq = task_rq(p);
dst_rq = cpu_rq(cpu);
p->on_rq = TASK_ON_RQ_MIGRATING;
deactivate_task(src_rq, p, 0);
set_task_cpu(p, cpu);
activate_task(dst_rq, p, 0);
p->on_rq = TASK_ON_RQ_QUEUED;
check_preempt_curr(dst_rq, p, 0);
} else {
/*
@@ -2194,6 +2205,10 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_FAIR_GROUP_SCHED
p->se.cfs_rq = NULL;
#endif
#ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif
@@ -7442,6 +7457,9 @@ int in_sched_functions(unsigned long addr)
*/
struct task_group root_task_group;
LIST_HEAD(task_groups);
/* Cacheline aligned slab cache for task_group */
static struct kmem_cache *task_group_cache __read_mostly;
#endif
DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
@@ -7499,11 +7517,12 @@ void __init sched_init(void)
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CGROUP_SCHED
task_group_cache = KMEM_CACHE(task_group, 0);
list_add(&root_task_group.list, &task_groups);
INIT_LIST_HEAD(&root_task_group.children);
INIT_LIST_HEAD(&root_task_group.siblings);
autogroup_init(&init_task);
#endif /* CONFIG_CGROUP_SCHED */
for_each_possible_cpu(i) {
@@ -7784,7 +7803,7 @@ static void free_sched_group(struct task_group *tg)
free_fair_sched_group(tg);
free_rt_sched_group(tg);
autogroup_free(tg);
kfree(tg);
kmem_cache_free(task_group_cache, tg);
}
/* allocate runqueue etc for a new task group */
@@ -7792,7 +7811,7 @@ struct task_group *sched_create_group(struct task_group *parent)
{
struct task_group *tg;
tg = kzalloc(sizeof(*tg), GFP_KERNEL);
tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
if (!tg)
return ERR_PTR(-ENOMEM);
@@ -8697,3 +8716,44 @@ void dump_cpu_task(int cpu)
pr_info("Task dump for CPU %d:\n", cpu);
sched_show_task(cpu_curr(cpu));
}
/*
* Nice levels are multiplicative, with a gentle 10% change for every
* nice level changed. I.e. when a CPU-bound task goes from nice 0 to
* nice 1, it will get ~10% less CPU time than another CPU-bound task
* that remained on nice 0.
*
* The "10% effect" is relative and cumulative: from _any_ nice level,
* if you go up 1 level, it's -10% CPU usage, if you go down 1 level
* it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
* If a task goes up by ~10% and another task goes down by ~10% then
* the relative distance between them is ~25%.)
*/
const int sched_prio_to_weight[40] = {
/* -20 */ 88761, 71755, 56483, 46273, 36291,
/* -15 */ 29154, 23254, 18705, 14949, 11916,
/* -10 */ 9548, 7620, 6100, 4904, 3906,
/* -5 */ 3121, 2501, 1991, 1586, 1277,
/* 0 */ 1024, 820, 655, 526, 423,
/* 5 */ 335, 272, 215, 172, 137,
/* 10 */ 110, 87, 70, 56, 45,
/* 15 */ 36, 29, 23, 18, 15,
};
/*
* Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
*
* In cases where the weight does not change often, we can use the
* precalculated inverse to speed up arithmetics by turning divisions
* into multiplications:
*/
const u32 sched_prio_to_wmult[40] = {
/* -20 */ 48388, 59856, 76040, 92818, 118348,
/* -15 */ 147320, 184698, 229616, 287308, 360437,
/* -10 */ 449829, 563644, 704093, 875809, 1099582,
/* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
/* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
/* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
/* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};

74
kernel/sched/cputime.c
View File

@@ -466,7 +466,7 @@ void account_process_tick(struct task_struct *p, int user_tick)
cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
struct rq *rq = this_rq();
if (vtime_accounting_enabled())
if (vtime_accounting_cpu_enabled())
return;
if (sched_clock_irqtime) {
@@ -680,7 +680,7 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
{
unsigned long long delta = vtime_delta(tsk);
WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
tsk->vtime_snap += delta;
/* CHECKME: always safe to convert nsecs to cputime? */
@@ -696,37 +696,37 @@ static void __vtime_account_system(struct task_struct *tsk)
void vtime_account_system(struct task_struct *tsk)
{
write_seqlock(&tsk->vtime_seqlock);
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
write_sequnlock(&tsk->vtime_seqlock);
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_gen_account_irq_exit(struct task_struct *tsk)
{
write_seqlock(&tsk->vtime_seqlock);
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
if (context_tracking_in_user())
tsk->vtime_snap_whence = VTIME_USER;
write_sequnlock(&tsk->vtime_seqlock);
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_account_user(struct task_struct *tsk)
{
cputime_t delta_cpu;
write_seqlock(&tsk->vtime_seqlock);
write_seqcount_begin(&tsk->vtime_seqcount);
delta_cpu = get_vtime_delta(tsk);
tsk->vtime_snap_whence = VTIME_SYS;
account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
write_sequnlock(&tsk->vtime_seqlock);
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_user_enter(struct task_struct *tsk)
{
write_seqlock(&tsk->vtime_seqlock);
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
tsk->vtime_snap_whence = VTIME_USER;
write_sequnlock(&tsk->vtime_seqlock);
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_guest_enter(struct task_struct *tsk)
@@ -738,19 +738,19 @@ void vtime_guest_enter(struct task_struct *tsk)
* synchronization against the reader (task_gtime())
* that can thus safely catch up with a tickless delta.
*/
write_seqlock(&tsk->vtime_seqlock);
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
current->flags |= PF_VCPU;
write_sequnlock(&tsk->vtime_seqlock);
write_seqcount_end(&tsk->vtime_seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_enter);
void vtime_guest_exit(struct task_struct *tsk)
{
write_seqlock(&tsk->vtime_seqlock);
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
current->flags &= ~PF_VCPU;
write_sequnlock(&tsk->vtime_seqlock);
write_seqcount_end(&tsk->vtime_seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_exit);
@@ -763,24 +763,26 @@ void vtime_account_idle(struct task_struct *tsk)
void arch_vtime_task_switch(struct task_struct *prev)
{
write_seqlock(&prev->vtime_seqlock);
prev->vtime_snap_whence = VTIME_SLEEPING;
write_sequnlock(&prev->vtime_seqlock);
write_seqcount_begin(&prev->vtime_seqcount);
prev->vtime_snap_whence = VTIME_INACTIVE;
write_seqcount_end(&prev->vtime_seqcount);
write_seqlock(&current->vtime_seqlock);
write_seqcount_begin(&current->vtime_seqcount);
current->vtime_snap_whence = VTIME_SYS;
current->vtime_snap = sched_clock_cpu(smp_processor_id());
write_sequnlock(&current->vtime_seqlock);
write_seqcount_end(&current->vtime_seqcount);
}
void vtime_init_idle(struct task_struct *t, int cpu)
{
unsigned long flags;
write_seqlock_irqsave(&t->vtime_seqlock, flags);
local_irq_save(flags);
write_seqcount_begin(&t->vtime_seqcount);
t->vtime_snap_whence = VTIME_SYS;
t->vtime_snap = sched_clock_cpu(cpu);
write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
write_seqcount_end(&t->vtime_seqcount);
local_irq_restore(flags);
}
cputime_t task_gtime(struct task_struct *t)
@@ -788,17 +790,17 @@ cputime_t task_gtime(struct task_struct *t)
unsigned int seq;
cputime_t gtime;
if (!context_tracking_is_enabled())
if (!vtime_accounting_enabled())
return t->gtime;
do {
seq = read_seqbegin(&t->vtime_seqlock);
seq = read_seqcount_begin(&t->vtime_seqcount);
gtime = t->gtime;
if (t->flags & PF_VCPU)
if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU)
gtime += vtime_delta(t);
} while (read_seqretry(&t->vtime_seqlock, seq));
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
return gtime;
}
@@ -821,7 +823,7 @@ fetch_task_cputime(struct task_struct *t,
*udelta = 0;
*sdelta = 0;
seq = read_seqbegin(&t->vtime_seqlock);
seq = read_seqcount_begin(&t->vtime_seqcount);
if (u_dst)
*u_dst = *u_src;
@@ -829,7 +831,7 @@ fetch_task_cputime(struct task_struct *t,
*s_dst = *s_src;
/* Task is sleeping, nothing to add */
if (t->vtime_snap_whence == VTIME_SLEEPING ||
if (t->vtime_snap_whence == VTIME_INACTIVE ||
is_idle_task(t))
continue;
@@ -845,7 +847,7 @@ fetch_task_cputime(struct task_struct *t,
if (t->vtime_snap_whence == VTIME_SYS)
*sdelta = delta;
}
} while (read_seqretry(&t->vtime_seqlock, seq));
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
}
@@ -853,6 +855,14 @@ void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
{
cputime_t udelta, sdelta;
if (!vtime_accounting_enabled()) {
if (utime)
*utime = t->utime;
if (stime)
*stime = t->stime;
return;
}
fetch_task_cputime(t, utime, stime, &t->utime,
&t->stime, &udelta, &sdelta);
if (utime)
@@ -866,6 +876,14 @@ void task_cputime_scaled(struct task_struct *t,
{
cputime_t udelta, sdelta;
if (!vtime_accounting_enabled()) {
if (utimescaled)
*utimescaled = t->utimescaled;
if (stimescaled)
*stimescaled = t->stimescaled;
return;
}
fetch_task_cputime(t, utimescaled, stimescaled,
&t->utimescaled, &t->stimescaled, &udelta, &sdelta);
if (utimescaled)

59
kernel/sched/deadline.c
View File

@@ -176,8 +176,10 @@ static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
}
}
if (leftmost)
if (leftmost) {
dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks;
dl_rq->earliest_dl.next = p->dl.deadline;
}
rb_link_node(&p->pushable_dl_tasks, parent, link);
rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
@@ -195,6 +197,10 @@ static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
next_node = rb_next(&p->pushable_dl_tasks);
dl_rq->pushable_dl_tasks_leftmost = next_node;
if (next_node) {
dl_rq->earliest_dl.next = rb_entry(next_node,
struct task_struct, pushable_dl_tasks)->dl.deadline;
}
}
rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
@@ -782,42 +788,14 @@ static void update_curr_dl(struct rq *rq)
#ifdef CONFIG_SMP
static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu);
static inline u64 next_deadline(struct rq *rq)
{
struct task_struct *next = pick_next_earliest_dl_task(rq, rq->cpu);
if (next && dl_prio(next->prio))
return next->dl.deadline;
else
return 0;
}
static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
{
struct rq *rq = rq_of_dl_rq(dl_rq);
if (dl_rq->earliest_dl.curr == 0 ||
dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
/*
* If the dl_rq had no -deadline tasks, or if the new task
* has shorter deadline than the current one on dl_rq, we
* know that the previous earliest becomes our next earliest,
* as the new task becomes the earliest itself.
*/
dl_rq->earliest_dl.next = dl_rq->earliest_dl.curr;
dl_rq->earliest_dl.curr = deadline;
cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
} else if (dl_rq->earliest_dl.next == 0 ||
dl_time_before(deadline, dl_rq->earliest_dl.next)) {
/*
* On the other hand, if the new -deadline task has a
* a later deadline than the earliest one on dl_rq, but
* it is earlier than the next (if any), we must
* recompute the next-earliest.
*/
dl_rq->earliest_dl.next = next_deadline(rq);
}
}
@@ -839,7 +817,6 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
dl_rq->earliest_dl.curr = entry->deadline;
dl_rq->earliest_dl.next = next_deadline(rq);
cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
}
}
@@ -1274,28 +1251,6 @@ static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
return 0;
}
/* Returns the second earliest -deadline task, NULL otherwise */
static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu)
{
struct rb_node *next_node = rq->dl.rb_leftmost;
struct sched_dl_entity *dl_se;
struct task_struct *p = NULL;
next_node:
next_node = rb_next(next_node);
if (next_node) {
dl_se = rb_entry(next_node, struct sched_dl_entity, rb_node);
p = dl_task_of(dl_se);
if (pick_dl_task(rq, p, cpu))
return p;
goto next_node;
}
return NULL;
}
/*
* Return the earliest pushable rq's task, which is suitable to be executed
* on the CPU, NULL otherwise:

316
kernel/sched/fair.c
View File

@@ -738,12 +738,56 @@ static void update_curr_fair(struct rq *rq)
update_curr(cfs_rq_of(&rq->curr->se));
}
#ifdef CONFIG_SCHEDSTATS
static inline void
update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq)));
u64 wait_start = rq_clock(rq_of(cfs_rq));
if (entity_is_task(se) && task_on_rq_migrating(task_of(se)) &&
likely(wait_start > se->statistics.wait_start))
wait_start -= se->statistics.wait_start;
se->statistics.wait_start = wait_start;
}
static void
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
struct task_struct *p;
u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start;
if (entity_is_task(se)) {
p = task_of(se);
if (task_on_rq_migrating(p)) {
/*
* Preserve migrating task's wait time so wait_start
* time stamp can be adjusted to accumulate wait time
* prior to migration.
*/
se->statistics.wait_start = delta;
return;
}
trace_sched_stat_wait(p, delta);
}
se->statistics.wait_max = max(se->statistics.wait_max, delta);
se->statistics.wait_count++;
se->statistics.wait_sum += delta;
se->statistics.wait_start = 0;
}
#else
static inline void
update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
}
static inline void
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
}
#endif
/*
* Task is being enqueued - update stats:
*/
@@ -757,23 +801,6 @@ static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
update_stats_wait_start(cfs_rq, se);
}
static void
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start));
schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start);
#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
trace_sched_stat_wait(task_of(se),
rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start);
}
#endif
schedstat_set(se->statistics.wait_start, 0);
}
static inline void
update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
@@ -2155,6 +2182,7 @@ void task_numa_work(struct callback_head *work)
unsigned long migrate, next_scan, now = jiffies;
struct task_struct *p = current;
struct mm_struct *mm = p->mm;
u64 runtime = p->se.sum_exec_runtime;
struct vm_area_struct *vma;
unsigned long start, end;
unsigned long nr_pte_updates = 0;
@@ -2277,6 +2305,17 @@ out:
else
reset_ptenuma_scan(p);
up_read(&mm->mmap_sem);
/*
* Make sure tasks use at least 32x as much time to run other code
* than they used here, to limit NUMA PTE scanning overhead to 3% max.
* Usually update_task_scan_period slows down scanning enough; on an
* overloaded system we need to limit overhead on a per task basis.
*/
if (unlikely(p->se.sum_exec_runtime != runtime)) {
u64 diff = p->se.sum_exec_runtime - runtime;
p->node_stamp += 32 * diff;
}
}
/*
@@ -2670,12 +2709,64 @@ static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force)
{
long delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
/*
* No need to update load_avg for root_task_group as it is not used.
*/
if (cfs_rq->tg == &root_task_group)
return;
if (force || abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
atomic_long_add(delta, &cfs_rq->tg->load_avg);
cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
}
}
/*
* Called within set_task_rq() right before setting a task's cpu. The
* caller only guarantees p->pi_lock is held; no other assumptions,
* including the state of rq->lock, should be made.
*/
void set_task_rq_fair(struct sched_entity *se,
struct cfs_rq *prev, struct cfs_rq *next)
{
if (!sched_feat(ATTACH_AGE_LOAD))
return;
/*
* We are supposed to update the task to "current" time, then its up to
* date and ready to go to new CPU/cfs_rq. But we have difficulty in
* getting what current time is, so simply throw away the out-of-date
* time. This will result in the wakee task is less decayed, but giving
* the wakee more load sounds not bad.
*/
if (se->avg.last_update_time && prev) {
u64 p_last_update_time;
u64 n_last_update_time;
#ifndef CONFIG_64BIT
u64 p_last_update_time_copy;
u64 n_last_update_time_copy;
do {
p_last_update_time_copy = prev->load_last_update_time_copy;
n_last_update_time_copy = next->load_last_update_time_copy;
smp_rmb();
p_last_update_time = prev->avg.last_update_time;
n_last_update_time = next->avg.last_update_time;
} while (p_last_update_time != p_last_update_time_copy ||
n_last_update_time != n_last_update_time_copy);
#else
p_last_update_time = prev->avg.last_update_time;
n_last_update_time = next->avg.last_update_time;
#endif
__update_load_avg(p_last_update_time, cpu_of(rq_of(prev)),
&se->avg, 0, 0, NULL);
se->avg.last_update_time = n_last_update_time;
}
}
#else /* CONFIG_FAIR_GROUP_SCHED */
static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) {}
#endif /* CONFIG_FAIR_GROUP_SCHED */
@@ -2809,6 +2900,27 @@ dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
max_t(s64, cfs_rq->runnable_load_sum - se->avg.load_sum, 0);
}
#ifndef CONFIG_64BIT
static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
{
u64 last_update_time_copy;
u64 last_update_time;
do {
last_update_time_copy = cfs_rq->load_last_update_time_copy;
smp_rmb();
last_update_time = cfs_rq->avg.last_update_time;
} while (last_update_time != last_update_time_copy);
return last_update_time;
}
#else
static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
{
return cfs_rq->avg.last_update_time;
}
#endif
/*
* Task first catches up with cfs_rq, and then subtract
* itself from the cfs_rq (task must be off the queue now).
@@ -2818,41 +2930,20 @@ void remove_entity_load_avg(struct sched_entity *se)
struct cfs_rq *cfs_rq = cfs_rq_of(se);
u64 last_update_time;
#ifndef CONFIG_64BIT
u64 last_update_time_copy;
/*
* Newly created task or never used group entity should not be removed
* from its (source) cfs_rq
*/
if (se->avg.last_update_time == 0)
return;
do {
last_update_time_copy = cfs_rq->load_last_update_time_copy;
smp_rmb();
last_update_time = cfs_rq->avg.last_update_time;
} while (last_update_time != last_update_time_copy);
#else
last_update_time = cfs_rq->avg.last_update_time;
#endif
last_update_time = cfs_rq_last_update_time(cfs_rq);
__update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0, NULL);
atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg);
atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg);
}
/*
* Update the rq's load with the elapsed running time before entering
* idle. if the last scheduled task is not a CFS task, idle_enter will
* be the only way to update the runnable statistic.
*/
void idle_enter_fair(struct rq *this_rq)
{
}
/*
* Update the rq's load with the elapsed idle time before a task is
* scheduled. if the newly scheduled task is not a CFS task, idle_exit will
* be the only way to update the runnable statistic.
*/
void idle_exit_fair(struct rq *this_rq)
{
}
static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq)
{
return cfs_rq->runnable_load_avg;
@@ -4240,42 +4331,37 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
*/
/*
* The exact cpuload at various idx values, calculated at every tick would be
* load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
* The exact cpuload calculated at every tick would be:
*
* If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
* on nth tick when cpu may be busy, then we have:
* load = ((2^idx - 1) / 2^idx)^(n-1) * load
* load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
* load' = (1 - 1/2^i) * load + (1/2^i) * cur_load
*
* If a cpu misses updates for n ticks (as it was idle) and update gets
* called on the n+1-th tick when cpu may be busy, then we have:
*
* load_n = (1 - 1/2^i)^n * load_0
* load_n+1 = (1 - 1/2^i) * load_n + (1/2^i) * cur_load
*
* decay_load_missed() below does efficient calculation of
* load = ((2^idx - 1) / 2^idx)^(n-1) * load
* avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
*
* load' = (1 - 1/2^i)^n * load
*
* Because x^(n+m) := x^n * x^m we can decompose any x^n in power-of-2 factors.
* This allows us to precompute the above in said factors, thereby allowing the
* reduction of an arbitrary n in O(log_2 n) steps. (See also
* fixed_power_int())
*
* The calculation is approximated on a 128 point scale.
* degrade_zero_ticks is the number of ticks after which load at any
* particular idx is approximated to be zero.
* degrade_factor is a precomputed table, a row for each load idx.
* Each column corresponds to degradation factor for a power of two ticks,
* based on 128 point scale.
* Example:
* row 2, col 3 (=12) says that the degradation at load idx 2 after
* 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
*
* With this power of 2 load factors, we can degrade the load n times
* by looking at 1 bits in n and doing as many mult/shift instead of
* n mult/shifts needed by the exact degradation.
*/
#define DEGRADE_SHIFT 7
static const unsigned char
degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
static const unsigned char
degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
{0, 0, 0, 0, 0, 0, 0, 0},
{64, 32, 8, 0, 0, 0, 0, 0},
{96, 72, 40, 12, 1, 0, 0},
{112, 98, 75, 43, 15, 1, 0},
{120, 112, 98, 76, 45, 16, 2} };
static const u8 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
static const u8 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
{ 0, 0, 0, 0, 0, 0, 0, 0 },
{ 64, 32, 8, 0, 0, 0, 0, 0 },
{ 96, 72, 40, 12, 1, 0, 0, 0 },
{ 112, 98, 75, 43, 15, 1, 0, 0 },
{ 120, 112, 98, 76, 45, 16, 2, 0 }
};
/*
* Update cpu_load for any missed ticks, due to tickless idle. The backlog
@@ -4306,14 +4392,46 @@ decay_load_missed(unsigned long load, unsigned long missed_updates, int idx)
return load;
}
/*
/**
* __update_cpu_load - update the rq->cpu_load[] statistics
* @this_rq: The rq to update statistics for
* @this_load: The current load
* @pending_updates: The number of missed updates
* @active: !0 for NOHZ_FULL
*
* Update rq->cpu_load[] statistics. This function is usually called every
* scheduler tick (TICK_NSEC). With tickless idle this will not be called
* every tick. We fix it up based on jiffies.
* scheduler tick (TICK_NSEC).
*
* This function computes a decaying average:
*
* load[i]' = (1 - 1/2^i) * load[i] + (1/2^i) * load
*
* Because of NOHZ it might not get called on every tick which gives need for
* the @pending_updates argument.
*
* load[i]_n = (1 - 1/2^i) * load[i]_n-1 + (1/2^i) * load_n-1
* = A * load[i]_n-1 + B ; A := (1 - 1/2^i), B := (1/2^i) * load
* = A * (A * load[i]_n-2 + B) + B
* = A * (A * (A * load[i]_n-3 + B) + B) + B
* = A^3 * load[i]_n-3 + (A^2 + A + 1) * B
* = A^n * load[i]_0 + (A^(n-1) + A^(n-2) + ... + 1) * B
* = A^n * load[i]_0 + ((1 - A^n) / (1 - A)) * B
* = (1 - 1/2^i)^n * (load[i]_0 - load) + load
*
* In the above we've assumed load_n := load, which is true for NOHZ_FULL as
* any change in load would have resulted in the tick being turned back on.
*
* For regular NOHZ, this reduces to:
*
* load[i]_n = (1 - 1/2^i)^n * load[i]_0
*
* see decay_load_misses(). For NOHZ_FULL we get to subtract and add the extra
* term. See the @active paramter.
*/
static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
unsigned long pending_updates)
unsigned long pending_updates, int active)
{
unsigned long tickless_load = active ? this_rq->cpu_load[0] : 0;
int i, scale;
this_rq->nr_load_updates++;
@@ -4325,8 +4443,9 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
/* scale is effectively 1 << i now, and >> i divides by scale */
old_load = this_rq->cpu_load[i];
old_load = this_rq->cpu_load[i] - tickless_load;
old_load = decay_load_missed(old_load, pending_updates - 1, i);
old_load += tickless_load;
new_load = this_load;
/*
* Round up the averaging division if load is increasing. This
@@ -4381,16 +4500,17 @@ static void update_idle_cpu_load(struct rq *this_rq)
pending_updates = curr_jiffies - this_rq->last_load_update_tick;
this_rq->last_load_update_tick = curr_jiffies;
__update_cpu_load(this_rq, load, pending_updates);
__update_cpu_load(this_rq, load, pending_updates, 0);
}
/*
* Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
*/
void update_cpu_load_nohz(void)
void update_cpu_load_nohz(int active)
{
struct rq *this_rq = this_rq();
unsigned long curr_jiffies = READ_ONCE(jiffies);
unsigned long load = active ? weighted_cpuload(cpu_of(this_rq)) : 0;
unsigned long pending_updates;
if (curr_jiffies == this_rq->last_load_update_tick)
@@ -4401,10 +4521,11 @@ void update_cpu_load_nohz(void)
if (pending_updates) {
this_rq->last_load_update_tick = curr_jiffies;
/*
* We were idle, this means load 0, the current load might be
* !0 due to remote wakeups and the sort.
* In the regular NOHZ case, we were idle, this means load 0.
* In the NOHZ_FULL case, we were non-idle, we should consider
* its weighted load.
*/
__update_cpu_load(this_rq, 0, pending_updates);
__update_cpu_load(this_rq, load, pending_updates, active);
}
raw_spin_unlock(&this_rq->lock);
}
@@ -4420,7 +4541,7 @@ void update_cpu_load_active(struct rq *this_rq)
* See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
*/
this_rq->last_load_update_tick = jiffies;
__update_cpu_load(this_rq, load, 1);
__update_cpu_load(this_rq, load, 1, 1);
}
/*
@@ -5007,8 +5128,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
/*
* Called immediately before a task is migrated to a new cpu; task_cpu(p) and
* cfs_rq_of(p) references at time of call are still valid and identify the
* previous cpu. However, the caller only guarantees p->pi_lock is held; no
* other assumptions, including the state of rq->lock, should be made.
* previous cpu. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
*/
static void migrate_task_rq_fair(struct task_struct *p)
{
@@ -5721,8 +5841,8 @@ static void detach_task(struct task_struct *p, struct lb_env *env)
{
lockdep_assert_held(&env->src_rq->lock);
deactivate_task(env->src_rq, p, 0);
p->on_rq = TASK_ON_RQ_MIGRATING;
deactivate_task(env->src_rq, p, 0);
set_task_cpu(p, env->dst_cpu);
}
@@ -5855,8 +5975,8 @@ static void attach_task(struct rq *rq, struct task_struct *p)
lockdep_assert_held(&rq->lock);
BUG_ON(task_rq(p) != rq);
p->on_rq = TASK_ON_RQ_QUEUED;
activate_task(rq, p, 0);
p->on_rq = TASK_ON_RQ_QUEUED;
check_preempt_curr(rq, p, 0);
}
@@ -6302,7 +6422,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
bool *overload)
{
unsigned long load;
int i;
int i, nr_running;
memset(sgs, 0, sizeof(*sgs));
@@ -6319,7 +6439,8 @@ static inline void update_sg_lb_stats(struct lb_env *env,
sgs->group_util += cpu_util(i);
sgs->sum_nr_running += rq->cfs.h_nr_running;
if (rq->nr_running > 1)
nr_running = rq->nr_running;
if (nr_running > 1)
*overload = true;
#ifdef CONFIG_NUMA_BALANCING
@@ -6327,7 +6448,10 @@ static inline void update_sg_lb_stats(struct lb_env *env,
sgs->nr_preferred_running += rq->nr_preferred_running;
#endif
sgs->sum_weighted_load += weighted_cpuload(i);
if (idle_cpu(i))
/*
* No need to call idle_cpu() if nr_running is not 0
*/
if (!nr_running && idle_cpu(i))
sgs->idle_cpus++;
}
@@ -7248,8 +7372,6 @@ static int idle_balance(struct rq *this_rq)
int pulled_task = 0;
u64 curr_cost = 0;
idle_enter_fair(this_rq);
/*
* We must set idle_stamp _before_ calling idle_balance(), such that we
* measure the duration of idle_balance() as idle time.
@@ -7330,10 +7452,8 @@ out:
if (this_rq->nr_running != this_rq->cfs.h_nr_running)
pulled_task = -1;
if (pulled_task) {
idle_exit_fair(this_rq);
if (pulled_task)
this_rq->idle_stamp = 0;
}
return pulled_task;
}

1
kernel/sched/idle_task.c
View File

@@ -47,7 +47,6 @@ dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
idle_exit_fair(rq);
rq_last_tick_reset(rq);
}

68
kernel/sched/sched.h
View File

@@ -248,7 +248,12 @@ struct task_group {
unsigned long shares;
#ifdef CONFIG_SMP
atomic_long_t load_avg;
/*
* load_avg can be heavily contended at clock tick time, so put
* it in its own cacheline separated from the fields above which
* will also be accessed at each tick.
*/
atomic_long_t load_avg ____cacheline_aligned;
#endif
#endif
@@ -335,7 +340,15 @@ extern void sched_move_task(struct task_struct *tsk);
#ifdef CONFIG_FAIR_GROUP_SCHED
extern int sched_group_set_shares(struct task_group *tg, unsigned long shares);
#endif
#ifdef CONFIG_SMP
extern void set_task_rq_fair(struct sched_entity *se,
struct cfs_rq *prev, struct cfs_rq *next);
#else /* !CONFIG_SMP */
static inline void set_task_rq_fair(struct sched_entity *se,
struct cfs_rq *prev, struct cfs_rq *next) { }
#endif /* CONFIG_SMP */
#endif /* CONFIG_FAIR_GROUP_SCHED */
#else /* CONFIG_CGROUP_SCHED */
@@ -933,6 +946,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
set_task_rq_fair(&p->se, p->se.cfs_rq, tg->cfs_rq[cpu]);
p->se.cfs_rq = tg->cfs_rq[cpu];
p->se.parent = tg->se[cpu];
#endif
@@ -1113,46 +1127,8 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
#define WEIGHT_IDLEPRIO 3
#define WMULT_IDLEPRIO 1431655765
/*
* Nice levels are multiplicative, with a gentle 10% change for every
* nice level changed. I.e. when a CPU-bound task goes from nice 0 to
* nice 1, it will get ~10% less CPU time than another CPU-bound task
* that remained on nice 0.
*
* The "10% effect" is relative and cumulative: from _any_ nice level,
* if you go up 1 level, it's -10% CPU usage, if you go down 1 level
* it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
* If a task goes up by ~10% and another task goes down by ~10% then
* the relative distance between them is ~25%.)
*/
static const int prio_to_weight[40] = {
/* -20 */ 88761, 71755, 56483, 46273, 36291,
/* -15 */ 29154, 23254, 18705, 14949, 11916,
/* -10 */ 9548, 7620, 6100, 4904, 3906,
/* -5 */ 3121, 2501, 1991, 1586, 1277,
/* 0 */ 1024, 820, 655, 526, 423,
/* 5 */ 335, 272, 215, 172, 137,
/* 10 */ 110, 87, 70, 56, 45,
/* 15 */ 36, 29, 23, 18, 15,
};
/*
* Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
*
* In cases where the weight does not change often, we can use the
* precalculated inverse to speed up arithmetics by turning divisions
* into multiplications:
*/
static const u32 prio_to_wmult[40] = {
/* -20 */ 48388, 59856, 76040, 92818, 118348,
/* -15 */ 147320, 184698, 229616, 287308, 360437,
/* -10 */ 449829, 563644, 704093, 875809, 1099582,
/* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
/* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
/* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
/* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};
extern const int sched_prio_to_weight[40];
extern const u32 sched_prio_to_wmult[40];
#define ENQUEUE_WAKEUP 0x01
#define ENQUEUE_HEAD 0x02
@@ -1252,16 +1228,8 @@ extern void update_group_capacity(struct sched_domain *sd, int cpu);
extern void trigger_load_balance(struct rq *rq);
extern void idle_enter_fair(struct rq *this_rq);
extern void idle_exit_fair(struct rq *this_rq);
extern void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask);
#else
static inline void idle_enter_fair(struct rq *rq) { }
static inline void idle_exit_fair(struct rq *rq) { }
#endif
#ifdef CONFIG_CPU_IDLE