Commit 3d4b47b4 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Implement on-demand (active) cfs_rq list 



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: default avatarPaul Turner <pjt@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101115234937.666535048@google.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 2069dd75

kernel/sched.c

+28 −77
Original line number Diff line number Diff line
@@ -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;

kernel/sched_fair.c

+40 −6
Original line number Diff line number Diff line
@@ -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);

	}

kernel/sched_rt.c

+24 −0
Original line number Diff line number Diff line
@@ -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);

}



/*

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