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sched: Implement on-demand (active) cfs_rq list

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Make certain load-balance actions scale per number of active cgroups
instead of the number of existing cgroups.

This makes wakeup/sleep paths more expensive, but is a win for systems
where the vast majority of existing cgroups are idle.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101115234937.666535048@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-11-15 15:47:01 -08:00 committed by Ingo Molnar
parent 2069dd75c7
commit 3d4b47b4b0
3 changed files with 92 additions and 83 deletions
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105
kernel/sched.c
View File

@ -274,9 +274,7 @@ struct task_group {
#define root_task_group init_task_group
/* task_group_lock serializes add/remove of task groups and also changes to
* a task group's cpu shares.
*/
/* task_group_lock serializes the addition/removal of task groups */
static DEFINE_SPINLOCK(task_group_lock);
#ifdef CONFIG_FAIR_GROUP_SCHED
@ -344,6 +342,7 @@ struct cfs_rq {
* leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
* list is used during load balance.
*/
int on_list;
struct list_head leaf_cfs_rq_list;
struct task_group *tg; /* group that "owns" this runqueue */
@ -1547,7 +1546,7 @@ static unsigned long cpu_avg_load_per_task(int cpu)
#ifdef CONFIG_FAIR_GROUP_SCHED
static void update_cfs_load(struct cfs_rq *cfs_rq);
static void update_cfs_load(struct cfs_rq *cfs_rq, int lb);
static void update_cfs_shares(struct cfs_rq *cfs_rq);
/*
@ -1570,7 +1569,7 @@ static int tg_shares_up(struct task_group *tg, void *data)
raw_spin_lock_irqsave(&rq->lock, flags);
update_rq_clock(rq);
update_cfs_load(cfs_rq);
update_cfs_load(cfs_rq, 1);
load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
load_avg -= cfs_rq->load_contribution;
@ -7688,15 +7687,13 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
#ifdef CONFIG_FAIR_GROUP_SCHED
static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
struct sched_entity *se, int cpu, int add,
struct sched_entity *se, int cpu,
struct sched_entity *parent)
{
struct rq *rq = cpu_rq(cpu);
tg->cfs_rq[cpu] = cfs_rq;
init_cfs_rq(cfs_rq, rq);
cfs_rq->tg = tg;
if (add)
list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
tg->se[cpu] = se;
/* se could be NULL for init_task_group */
@ -7716,7 +7713,7 @@ static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
#ifdef CONFIG_RT_GROUP_SCHED
static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
struct sched_rt_entity *rt_se, int cpu, int add,
struct sched_rt_entity *rt_se, int cpu,
struct sched_rt_entity *parent)
{
struct rq *rq = cpu_rq(cpu);
@ -7725,8 +7722,6 @@ static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
init_rt_rq(rt_rq, rq);
rt_rq->tg = tg;
rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
if (add)
list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
tg->rt_se[cpu] = rt_se;
if (!rt_se)
@ -7835,7 +7830,7 @@ void __init sched_init(void)
* We achieve this by letting init_task_group's tasks sit
* directly in rq->cfs (i.e init_task_group->se[] = NULL).
*/
init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, NULL);
#endif
#endif /* CONFIG_FAIR_GROUP_SCHED */
@ -7843,7 +7838,7 @@ void __init sched_init(void)
#ifdef CONFIG_RT_GROUP_SCHED
INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
#ifdef CONFIG_CGROUP_SCHED
init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, NULL);
#endif
#endif
@ -8119,7 +8114,7 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
if (!se)
goto err_free_rq;
init_tg_cfs_entry(tg, cfs_rq, se, i, 0, parent->se[i]);
init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
}
return 1;
@ -8130,15 +8125,22 @@ err:
return 0;
}
static inline void register_fair_sched_group(struct task_group *tg, int cpu)
{
list_add_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list,
&cpu_rq(cpu)->leaf_cfs_rq_list);
}
static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
{
list_del_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list);
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
int i;
/*
* Only empty task groups can be destroyed; so we can speculatively
* check on_list without danger of it being re-added.
*/
if (!tg->cfs_rq[cpu]->on_list)
return;
raw_spin_lock_irqsave(&rq->lock, flags);
list_del_leaf_cfs_rq(tg->cfs_rq[i]);
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
#else /* !CONFG_FAIR_GROUP_SCHED */
static inline void free_fair_sched_group(struct task_group *tg)
@ -8151,10 +8153,6 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
return 1;
}
static inline void register_fair_sched_group(struct task_group *tg, int cpu)
{
}
static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
{
}
@ -8209,7 +8207,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
if (!rt_se)
goto err_free_rq;
init_tg_rt_entry(tg, rt_rq, rt_se, i, 0, parent->rt_se[i]);
init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
}
return 1;
@ -8219,17 +8217,6 @@ err_free_rq:
err:
return 0;
}
static inline void register_rt_sched_group(struct task_group *tg, int cpu)
{
list_add_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list,
&cpu_rq(cpu)->leaf_rt_rq_list);
}
static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
{
list_del_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list);
}
#else /* !CONFIG_RT_GROUP_SCHED */
static inline void free_rt_sched_group(struct task_group *tg)
{
@ -8240,14 +8227,6 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
return 1;
}
static inline void register_rt_sched_group(struct task_group *tg, int cpu)
{
}
static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
{
}
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CGROUP_SCHED
@ -8263,7 +8242,6 @@ struct task_group *sched_create_group(struct task_group *parent)
{
struct task_group *tg;
unsigned long flags;
int i;
tg = kzalloc(sizeof(*tg), GFP_KERNEL);
if (!tg)
@ -8276,10 +8254,6 @@ struct task_group *sched_create_group(struct task_group *parent)
goto err;
spin_lock_irqsave(&task_group_lock, flags);
for_each_possible_cpu(i) {
register_fair_sched_group(tg, i);
register_rt_sched_group(tg, i);
}
list_add_rcu(&tg->list, &task_groups);
WARN_ON(!parent); /* root should already exist */
@ -8309,11 +8283,11 @@ void sched_destroy_group(struct task_group *tg)
unsigned long flags;
int i;
spin_lock_irqsave(&task_group_lock, flags);
for_each_possible_cpu(i) {
/* end participation in shares distribution */
for_each_possible_cpu(i)
unregister_fair_sched_group(tg, i);
unregister_rt_sched_group(tg, i);
}
spin_lock_irqsave(&task_group_lock, flags);
list_del_rcu(&tg->list);
list_del_rcu(&tg->siblings);
spin_unlock_irqrestore(&task_group_lock, flags);
@ -8391,7 +8365,6 @@ static DEFINE_MUTEX(shares_mutex);
int sched_group_set_shares(struct task_group *tg, unsigned long shares)
{
int i;
unsigned long flags;
/*
* We can't change the weight of the root cgroup.
@ -8408,19 +8381,6 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
if (tg->shares == shares)
goto done;
spin_lock_irqsave(&task_group_lock, flags);
for_each_possible_cpu(i)
unregister_fair_sched_group(tg, i);
list_del_rcu(&tg->siblings);
spin_unlock_irqrestore(&task_group_lock, flags);
/* wait for any ongoing reference to this group to finish */
synchronize_sched();
/*
* Now we are free to modify the group's share on each cpu
* w/o tripping rebalance_share or load_balance_fair.
*/
tg->shares = shares;
for_each_possible_cpu(i) {
/*
@ -8429,15 +8389,6 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
set_se_shares(tg->se[i], shares);
}
/*
* Enable load balance activity on this group, by inserting it back on
* each cpu's rq->leaf_cfs_rq_list.
*/
spin_lock_irqsave(&task_group_lock, flags);
for_each_possible_cpu(i)
register_fair_sched_group(tg, i);
list_add_rcu(&tg->siblings, &tg->parent->children);
spin_unlock_irqrestore(&task_group_lock, flags);
done:
mutex_unlock(&shares_mutex);
return 0;

46
kernel/sched_fair.c
View File

@ -143,6 +143,24 @@ static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
return cfs_rq->tg->cfs_rq[this_cpu];
}
static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
if (!cfs_rq->on_list) {
list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
&rq_of(cfs_rq)->leaf_cfs_rq_list);
cfs_rq->on_list = 1;
}
}
static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
if (cfs_rq->on_list) {
list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
cfs_rq->on_list = 0;
}
}
/* Iterate thr' all leaf cfs_rq's on a runqueue */
#define for_each_leaf_cfs_rq(rq, cfs_rq) \
list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
@ -246,6 +264,14 @@ static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
return &cpu_rq(this_cpu)->cfs;
}
static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
}
static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
}
#define for_each_leaf_cfs_rq(rq, cfs_rq) \
for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
@ -648,7 +674,7 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
}
#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
static void update_cfs_load(struct cfs_rq *cfs_rq)
static void update_cfs_load(struct cfs_rq *cfs_rq, int lb)
{
u64 period = sched_avg_period();
u64 now, delta;
@ -673,6 +699,11 @@ static void update_cfs_load(struct cfs_rq *cfs_rq)
cfs_rq->load_period /= 2;
cfs_rq->load_avg /= 2;
}
if (lb && !cfs_rq->nr_running) {
if (cfs_rq->load_avg < (period / 8))
list_del_leaf_cfs_rq(cfs_rq);
}
}
static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
@ -719,7 +750,7 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq)
reweight_entity(cfs_rq_of(se), se, shares);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
static inline void update_cfs_load(struct cfs_rq *cfs_rq)
static inline void update_cfs_load(struct cfs_rq *cfs_rq, int lb)
{
}
@ -849,7 +880,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
update_cfs_load(cfs_rq);
update_cfs_load(cfs_rq, 0);
account_entity_enqueue(cfs_rq, se);
update_cfs_shares(cfs_rq);
@ -863,6 +894,9 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
if (se != cfs_rq->curr)
__enqueue_entity(cfs_rq, se);
se->on_rq = 1;
if (cfs_rq->nr_running == 1)
list_add_leaf_cfs_rq(cfs_rq);
}
static void __clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
@ -907,7 +941,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
if (se != cfs_rq->curr)
__dequeue_entity(cfs_rq, se);
se->on_rq = 0;
update_cfs_load(cfs_rq);
update_cfs_load(cfs_rq, 0);
account_entity_dequeue(cfs_rq, se);
update_min_vruntime(cfs_rq);
update_cfs_shares(cfs_rq);
@ -1142,7 +1176,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);
update_cfs_load(cfs_rq);
update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq);
}
@ -1172,7 +1206,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);
update_cfs_load(cfs_rq);
update_cfs_load(cfs_rq, 0);
update_cfs_shares(cfs_rq);
}

24
kernel/sched_rt.c
View File

@ -183,6 +183,17 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)
return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
}
static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
list_add_rcu(&rt_rq->leaf_rt_rq_list,
&rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
}
static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
{
list_del_rcu(&rt_rq->leaf_rt_rq_list);
}
#define for_each_leaf_rt_rq(rt_rq, rq) \
list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
@ -276,6 +287,14 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)
return ktime_to_ns(def_rt_bandwidth.rt_period);
}
static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
}
static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
{
}
#define for_each_leaf_rt_rq(rt_rq, rq) \
for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
@ -825,6 +844,9 @@ static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
return;
if (!rt_rq->rt_nr_running)
list_add_leaf_rt_rq(rt_rq);
if (head)
list_add(&rt_se->run_list, queue);
else
@ -844,6 +866,8 @@ static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
__clear_bit(rt_se_prio(rt_se), array->bitmap);
dec_rt_tasks(rt_se, rt_rq);
if (!rt_rq->rt_nr_running)
list_del_leaf_rt_rq(rt_rq);
}
/*