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Commit ec2c507f authored by Srivatsa Vaddagiri's avatar Srivatsa Vaddagiri Committed by Ingo Molnar
Browse files

sched: group scheduling, minor fixes 



Minor bug fixes for the group scheduler:

- Use a mutex to serialize add/remove of task groups and also when
  changing shares of a task group. Use the same mutex when printing
  cfs_rq debugging stats for various task groups.

- Use list_for_each_entry_rcu in for_each_leaf_cfs_rq macro (when
  walking task group list)

Signed-off-by: default avatarSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 93f992cc

kernel/sched.c

+25 −8
Original line number Diff line number Diff line
@@ -169,8 +169,6 @@ struct task_group { 
	/* runqueue "owned" by this group on each cpu */

	struct cfs_rq **cfs_rq;

	unsigned long shares;

	/* spinlock to serialize modification to shares */

	spinlock_t lock;

	struct rcu_head rcu;

};
@@ -182,6 +180,11 @@ static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp; 
static struct sched_entity *init_sched_entity_p[NR_CPUS];

static struct cfs_rq *init_cfs_rq_p[NR_CPUS];



/* task_group_mutex serializes add/remove of task groups and also changes to

 * a task group's cpu shares.

 */

static DEFINE_MUTEX(task_group_mutex);



/* Default task group.

 *	Every task in system belong to this group at bootup.

 */
@@ -221,9 +224,21 @@ static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) 
	p->se.parent = task_group(p)->se[cpu];

}



static inline void lock_task_group_list(void)

{

	mutex_lock(&task_group_mutex);

}



static inline void unlock_task_group_list(void)

{

	mutex_unlock(&task_group_mutex);

}



#else



static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) { }

static inline void lock_task_group_list(void) { }

static inline void unlock_task_group_list(void) { }



#endif	/* CONFIG_FAIR_GROUP_SCHED */
@@ -6768,7 +6783,6 @@ void __init sched_init(void) 
			se->parent = NULL;

		}

		init_task_group.shares = init_task_group_load;

		spin_lock_init(&init_task_group.lock);

#endif



		for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
@@ -7008,14 +7022,15 @@ struct task_group *sched_create_group(void) 
		se->parent = NULL;

	}



	tg->shares = NICE_0_LOAD;



	lock_task_group_list();

	for_each_possible_cpu(i) {

		rq = cpu_rq(i);

		cfs_rq = tg->cfs_rq[i];

		list_add_rcu(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);

	}



	tg->shares = NICE_0_LOAD;

	spin_lock_init(&tg->lock);

	unlock_task_group_list();



	return tg;
@@ -7061,10 +7076,12 @@ void sched_destroy_group(struct task_group *tg) 
	struct cfs_rq *cfs_rq = NULL;

	int i;



	lock_task_group_list();

	for_each_possible_cpu(i) {

		cfs_rq = tg->cfs_rq[i];

		list_del_rcu(&cfs_rq->leaf_cfs_rq_list);

	}

	unlock_task_group_list();



	BUG_ON(!cfs_rq);
@@ -7146,7 +7163,7 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares) 
	if (shares < 2)

		shares = 2;



	spin_lock(&tg->lock);

	lock_task_group_list();

	if (tg->shares == shares)

		goto done;
@@ -7155,7 +7172,7 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares) 
		set_se_shares(tg->se[i], shares);



done:

	spin_unlock(&tg->lock);

	unlock_task_group_list();

	return 0;

}

kernel/sched_fair.c

+3 −1
Original line number Diff line number Diff line
@@ -690,7 +690,7 @@ static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) 


/* Iterate thr' all leaf cfs_rq's on a runqueue */

#define for_each_leaf_cfs_rq(rq, cfs_rq) \

	list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)

	list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)



/* Do the two (enqueued) entities belong to the same group ? */

static inline int
@@ -1132,7 +1132,9 @@ static void print_cfs_stats(struct seq_file *m, int cpu) 
#ifdef CONFIG_FAIR_GROUP_SCHED

	print_cfs_rq(m, cpu, &cpu_rq(cpu)->cfs);

#endif

	lock_task_group_list();

	for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)

		print_cfs_rq(m, cpu, cfs_rq);

	unlock_task_group_list();

}

#endif