Commit 24e377a8 authored by Srivatsa Vaddagiri's avatar Srivatsa Vaddagiri Committed by Ingo Molnar

sched: add fair-user scheduler

Enable user-id based fair group scheduling. This is useful for anyone
who wants to test the group scheduler w/o having to enable
CONFIG_CGROUPS.

A separate scheduling group (i.e struct task_grp) is automatically created for 
every new user added to the system. Upon uid change for a task, it is made to 
move to the corresponding scheduling group.

A /proc tunable (/proc/root_user_share) is also provided to tune root
user's quota of cpu bandwidth.
Signed-off-by: default avatarSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: default avatarDhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 9b5b7751
......@@ -597,6 +597,10 @@ struct user_struct {
/* Hash table maintenance information */
struct hlist_node uidhash_node;
uid_t uid;
#ifdef CONFIG_FAIR_USER_SCHED
struct task_grp *tg;
#endif
};
extern struct user_struct *find_user(uid_t);
......
......@@ -289,6 +289,19 @@ config FAIR_GROUP_SCHED
This feature lets cpu scheduler recognize task groups and control cpu
bandwidth allocation to such task groups.
choice
depends on FAIR_GROUP_SCHED
prompt "Basis for grouping tasks"
default FAIR_USER_SCHED
config FAIR_USER_SCHED
bool "user id"
help
This option will choose userid as the basis for grouping
tasks, thus providing equal cpu bandwidth to each user.
endchoice
config SYSFS_DEPRECATED
bool "Create deprecated sysfs files"
default y
......
......@@ -200,7 +200,12 @@ struct task_grp init_task_grp = {
.cfs_rq = init_cfs_rq_p,
};
#ifdef CONFIG_FAIR_USER_SCHED
#define INIT_TASK_GRP_LOAD 2*NICE_0_LOAD
#else
#define INIT_TASK_GRP_LOAD NICE_0_LOAD
#endif
static int init_task_grp_load = INIT_TASK_GRP_LOAD;
/* return group to which a task belongs */
......@@ -208,7 +213,11 @@ static inline struct task_grp *task_grp(struct task_struct *p)
{
struct task_grp *tg;
#ifdef CONFIG_FAIR_USER_SCHED
tg = p->user->tg;
#else
tg = &init_task_grp;
#endif
return tg;
}
......
......@@ -212,6 +212,49 @@ static void sysrq_sched_debug_show(void)
sched_debug_show(NULL, NULL);
}
#ifdef CONFIG_FAIR_USER_SCHED
static DEFINE_MUTEX(root_user_share_mutex);
static int
root_user_share_read_proc(char *page, char **start, off_t off, int count,
int *eof, void *data)
{
int len;
len = sprintf(page, "%d\n", init_task_grp_load);
return len;
}
static int
root_user_share_write_proc(struct file *file, const char __user *buffer,
unsigned long count, void *data)
{
unsigned long shares;
char kbuf[sizeof(unsigned long)+1];
int rc = 0;
if (copy_from_user(kbuf, buffer, sizeof(kbuf)))
return -EFAULT;
shares = simple_strtoul(kbuf, NULL, 0);
if (!shares)
shares = NICE_0_LOAD;
mutex_lock(&root_user_share_mutex);
init_task_grp_load = shares;
rc = sched_group_set_shares(&init_task_grp, shares);
mutex_unlock(&root_user_share_mutex);
return (rc < 0 ? rc : count);
}
#endif /* CONFIG_FAIR_USER_SCHED */
static int sched_debug_open(struct inode *inode, struct file *filp)
{
return single_open(filp, sched_debug_show, NULL);
......@@ -234,6 +277,15 @@ static int __init init_sched_debug_procfs(void)
pe->proc_fops = &sched_debug_fops;
#ifdef CONFIG_FAIR_USER_SCHED
pe = create_proc_entry("root_user_share", 0644, NULL);
if (!pe)
return -ENOMEM;
pe->read_proc = root_user_share_read_proc;
pe->write_proc = root_user_share_write_proc;
#endif
return 0;
}
......
......@@ -50,8 +50,41 @@ struct user_struct root_user = {
.uid_keyring = &root_user_keyring,
.session_keyring = &root_session_keyring,
#endif
#ifdef CONFIG_FAIR_USER_SCHED
.tg = &init_task_grp,
#endif
};
#ifdef CONFIG_FAIR_USER_SCHED
static void sched_destroy_user(struct user_struct *up)
{
sched_destroy_group(up->tg);
}
static int sched_create_user(struct user_struct *up)
{
int rc = 0;
up->tg = sched_create_group();
if (IS_ERR(up->tg))
rc = -ENOMEM;
return rc;
}
static void sched_switch_user(struct task_struct *p)
{
sched_move_task(p);
}
#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) { }
#endif /* CONFIG_FAIR_USER_SCHED */
/*
* These routines must be called with the uidhash spinlock held!
*/
......@@ -109,6 +142,7 @@ void free_uid(struct user_struct *up)
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);
......@@ -150,6 +184,13 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
return NULL;
}
if (sched_create_user(new) < 0) {
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
return NULL;
}
/*
* Before adding this, check whether we raced
* on adding the same user already..
......@@ -157,6 +198,7 @@ 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);
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
......@@ -184,6 +226,7 @@ void switch_uid(struct user_struct *new_user)
atomic_dec(&old_user->processes);
switch_uid_keyring(new_user);
current->user = new_user;
sched_switch_user(current);
/*
* We need to synchronize with __sigqueue_alloc()
......
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