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sched: group scheduling, sysfs tunables

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Add tunables in sysfs to modify a user's cpu share.

A directory is created in sysfs for each new user in the system.

	/sys/kernel/uids/<uid>/cpu_share

Reading this file returns the cpu shares granted for the user.
Writing into this file modifies the cpu share for the user. Only an
administrator is allowed to modify a user's cpu share.

Ex:
	# cd /sys/kernel/uids/
	# cat 512/cpu_share
	1024
	# echo 2048 > 512/cpu_share
	# cat 512/cpu_share
	2048
	#

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Dhaval Giani
2007-10-15 17:00:14 +02:00
committed by Ingo Molnar
parent 8ca0e14ffb
commit 5cb350baf5
6 changed files with 317 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files

256
kernel/user.c
View File

@@ -55,7 +55,41 @@ struct user_struct root_user = {
#endif
};
/*
* These routines must be called with the uidhash spinlock held!
*/
static inline void uid_hash_insert(struct user_struct *up,
struct hlist_head *hashent)
{
hlist_add_head(&up->uidhash_node, hashent);
}
static inline void uid_hash_remove(struct user_struct *up)
{
hlist_del_init(&up->uidhash_node);
}
static inline struct user_struct *uid_hash_find(uid_t uid,
struct hlist_head *hashent)
{
struct user_struct *user;
struct hlist_node *h;
hlist_for_each_entry(user, h, hashent, uidhash_node) {
if (user->uid == uid) {
atomic_inc(&user->__count);
return user;
}
}
return NULL;
}
#ifdef CONFIG_FAIR_USER_SCHED
static struct kobject uids_kobject; /* represents /sys/kernel/uids directory */
static DEFINE_MUTEX(uids_mutex);
static void sched_destroy_user(struct user_struct *up)
{
sched_destroy_group(up->tg);
@@ -77,42 +111,173 @@ static void sched_switch_user(struct task_struct *p)
sched_move_task(p);
}
static inline void uids_mutex_lock(void)
{
mutex_lock(&uids_mutex);
}
static inline void uids_mutex_unlock(void)
{
mutex_unlock(&uids_mutex);
}
/* return cpu shares held by the user */
ssize_t cpu_shares_show(struct kset *kset, char *buffer)
{
struct user_struct *up = container_of(kset, struct user_struct, kset);
return sprintf(buffer, "%lu\n", sched_group_shares(up->tg));
}
/* modify cpu shares held by the user */
ssize_t cpu_shares_store(struct kset *kset, const char *buffer, size_t size)
{
struct user_struct *up = container_of(kset, struct user_struct, kset);
unsigned long shares;
int rc;
sscanf(buffer, "%lu", &shares);
rc = sched_group_set_shares(up->tg, shares);
return (rc ? rc : size);
}
static void user_attr_init(struct subsys_attribute *sa, char *name, int mode)
{
sa->attr.name = name;
sa->attr.mode = mode;
sa->show = cpu_shares_show;
sa->store = cpu_shares_store;
}
/* Create "/sys/kernel/uids/<uid>" directory and
* "/sys/kernel/uids/<uid>/cpu_share" file for this user.
*/
static int user_kobject_create(struct user_struct *up)
{
struct kset *kset = &up->kset;
struct kobject *kobj = &kset->kobj;
int error;
memset(kset, 0, sizeof(struct kset));
kobj->parent = &uids_kobject; /* create under /sys/kernel/uids dir */
kobject_set_name(kobj, "%d", up->uid);
kset_init(kset);
user_attr_init(&up->user_attr, "cpu_share", 0644);
error = kobject_add(kobj);
if (error)
goto done;
error = sysfs_create_file(kobj, &up->user_attr.attr);
if (error)
kobject_del(kobj);
done:
return error;
}
/* create these in sysfs filesystem:
* "/sys/kernel/uids" directory
* "/sys/kernel/uids/0" directory (for root user)
* "/sys/kernel/uids/0/cpu_share" file (for root user)
*/
int __init uids_kobject_init(void)
{
int error;
/* create under /sys/kernel dir */
uids_kobject.parent = &kernel_subsys.kobj;
kobject_set_name(&uids_kobject, "uids");
kobject_init(&uids_kobject);
error = kobject_add(&uids_kobject);
if (!error)
error = user_kobject_create(&root_user);
return error;
}
/* work function to remove sysfs directory for a user and free up
* corresponding structures.
*/
static void remove_user_sysfs_dir(struct work_struct *w)
{
struct user_struct *up = container_of(w, struct user_struct, work);
struct kobject *kobj = &up->kset.kobj;
unsigned long flags;
int remove_user = 0;
/* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
* atomic.
*/
uids_mutex_lock();
local_irq_save(flags);
if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
uid_hash_remove(up);
remove_user = 1;
spin_unlock_irqrestore(&uidhash_lock, flags);
} else {
local_irq_restore(flags);
}
if (!remove_user)
goto done;
sysfs_remove_file(kobj, &up->user_attr.attr);
kobject_del(kobj);
sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
done:
uids_mutex_unlock();
}
/* IRQs are disabled and uidhash_lock is held upon function entry.
* IRQ state (as stored in flags) is restored and uidhash_lock released
* upon function exit.
*/
static inline void free_user(struct user_struct *up, unsigned long flags)
{
/* restore back the count */
atomic_inc(&up->__count);
spin_unlock_irqrestore(&uidhash_lock, flags);
INIT_WORK(&up->work, remove_user_sysfs_dir);
schedule_work(&up->work);
}
#else /* CONFIG_FAIR_USER_SCHED */
static void sched_destroy_user(struct user_struct *up) { }
static int sched_create_user(struct user_struct *up) { return 0; }
static void sched_switch_user(struct task_struct *p) { }
static inline int user_kobject_create(struct user_struct *up) { return 0; }
static inline void uids_mutex_lock(void) { }
static inline void uids_mutex_unlock(void) { }
/* IRQs are disabled and uidhash_lock is held upon function entry.
* IRQ state (as stored in flags) is restored and uidhash_lock released
* upon function exit.
*/
static inline void free_user(struct user_struct *up, unsigned long flags)
{
uid_hash_remove(up);
spin_unlock_irqrestore(&uidhash_lock, flags);
sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
}
#endif /* CONFIG_FAIR_USER_SCHED */
/*
* These routines must be called with the uidhash spinlock held!
*/
static inline void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
{
hlist_add_head(&up->uidhash_node, hashent);
}
static inline void uid_hash_remove(struct user_struct *up)
{
hlist_del_init(&up->uidhash_node);
}
static inline struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
{
struct user_struct *user;
struct hlist_node *h;
hlist_for_each_entry(user, h, hashent, uidhash_node) {
if(user->uid == uid) {
atomic_inc(&user->__count);
return user;
}
}
return NULL;
}
/*
* Locate the user_struct for the passed UID. If found, take a ref on it. The
* caller must undo that ref with free_uid().
@@ -139,16 +304,10 @@ void free_uid(struct user_struct *up)
return;
local_irq_save(flags);
if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
uid_hash_remove(up);
spin_unlock_irqrestore(&uidhash_lock, flags);
sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
} else {
if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
free_user(up, flags);
else
local_irq_restore(flags);
}
}
struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
@@ -156,6 +315,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
struct hlist_head *hashent = uidhashentry(ns, uid);
struct user_struct *up;
/* Make uid_hash_find() + user_kobject_create() + uid_hash_insert()
* atomic.
*/
uids_mutex_lock();
spin_lock_irq(&uidhash_lock);
up = uid_hash_find(uid, hashent);
spin_unlock_irq(&uidhash_lock);
@@ -191,6 +355,15 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
return NULL;
}
if (user_kobject_create(new)) {
sched_destroy_user(new);
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
uids_mutex_unlock();
return NULL;
}
/*
* Before adding this, check whether we raced
* on adding the same user already..
@@ -198,7 +371,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
spin_lock_irq(&uidhash_lock);
up = uid_hash_find(uid, hashent);
if (up) {
sched_destroy_user(new);
/* This case is not possible when CONFIG_FAIR_USER_SCHED
* is defined, since we serialize alloc_uid() using
* uids_mutex. Hence no need to call
* sched_destroy_user() or remove_user_sysfs_dir().
*/
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
@@ -209,6 +386,9 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
spin_unlock_irq(&uidhash_lock);
}
uids_mutex_unlock();
return up;
}