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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: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Srivatsa Vaddagiri 2008-01-25 21:07:59 +01:00 committed by Ingo Molnar
parent 93f992ccc0
commit ec2c507fe8
2 changed files with 28 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
kernel/sched.c
View File

@ -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;
}

4
kernel/sched_fair.c
View File

@ -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