Re: [PATCH 4/5] Add fair-user scheduler

[roel <12o3l@tiscali.nl>]

Srivatsa Vaddagiri wrote:
> Enable user-id based fair group scheduling. This is usefull 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 : Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
> Signed-off-by : Dhaval Giani <dhaval@linux.vnet.ibm.com>
> 
> 
> ---
>  include/linux/sched.h |    4 +++
>  init/Kconfig          |   13 ++++++++++++
>  kernel/sched.c        |    9 ++++++++
>  kernel/sched_debug.c  |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  kernel/user.c         |   43 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 121 insertions(+)
> 
> Index: linux-2.6.23-rc6/include/linux/sched.h
> ===================================================================
> --- linux-2.6.23-rc6.orig/include/linux/sched.h
> +++ linux-2.6.23-rc6/include/linux/sched.h
> @@ -596,6 +596,10 @@ 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);
> Index: linux-2.6.23-rc6/init/Kconfig
> ===================================================================
> --- linux-2.6.23-rc6.orig/init/Kconfig
> +++ linux-2.6.23-rc6/init/Kconfig
> @@ -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
> Index: linux-2.6.23-rc6/kernel/sched.c
> ===================================================================
> --- linux-2.6.23-rc6.orig/kernel/sched.c
> +++ linux-2.6.23-rc6/kernel/sched.c
> @@ -199,7 +199,12 @@ 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 */
> @@ -207,7 +212,11 @@ static inline struct task_grp *task_grp(
>  {
>  	struct task_grp *tg;
>  
> +#ifdef CONFIG_FAIR_USER_SCHED
> +	tg = p->user->tg;
> +#else
>  	tg  = &init_task_grp;
> +#endif
>  
>  	return tg;
>  }
> Index: linux-2.6.23-rc6/kernel/sched_debug.c
> ===================================================================
> --- linux-2.6.23-rc6.orig/kernel/sched_debug.c
> +++ linux-2.6.23-rc6/kernel/sched_debug.c
> @@ -214,6 +214,49 @@ 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;
> +}

or use this oneliner:

	return sprintf(page, "%d\n", init_task_grp_load);

> +
> +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);
> @@ -236,6 +279,15 @@ static int __init init_sched_debug_procf
>  
>  	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;
>  }
>  
> Index: linux-2.6.23-rc6/kernel/user.c
> ===================================================================
> --- linux-2.6.23-rc6.orig/kernel/user.c
> +++ linux-2.6.23-rc6/kernel/user.c
> @@ -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 us
>  			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 us
>  		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_
>  	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()
>