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

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

include/linux/sched.h

+4 −0
Original line number Diff line number Diff line
@@ -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);

init/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -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

kernel/sched.c

+9 −0
Original line number Diff line number Diff line
@@ -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;

}

kernel/sched_debug.c

+52 −0
Original line number Diff line number Diff line
@@ -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;

}

kernel/user.c

+43 −0
Original line number Diff line number Diff line
@@ -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()