Search     or:     and:
 LINUX 
 Language 
 Kernel 
 Package 
 Book 
 Test 
 OS 
 Forum 
 iakovlev.org 
 Kernels
 Boot 
 Memory 
 File system
 0.01
 1.0 
 2.0 
 2.4 
 2.6 
 3.x 
 4.x 
 5.x 
 6.x 
 Интервью 
 Kernel
 HOW-TO 1
 Ptrace
 Kernel-Rebuild-HOWTO
 Runlevel
 Linux daemons
 FAQ
NEWS
Последние статьи :
  Тренажёр 16.01   
  Эльбрус 05.12   
  Алгоритмы 12.04   
  Rust 07.11   
  Go 25.12   
  EXT4 10.11   
  FS benchmark 15.09   
  Сетунь 23.07   
  Trees 25.06   
  Apache 03.02   
 
TOP 20
 Secure Programming for Li...6500 
 Linux Kernel 2.6...5278 
 Trees...1112 
 Максвелл 3...1046 
 William Gropp...984 
 Go Web ...953 
 Ethreal 3...921 
 Gary V.Vaughan-> Libtool...911 
 Ethreal 4...908 
 Ext4 FS...898 
 Clickhouse...895 
 Rodriguez 6...895 
 Ethreal 1...888 
 Steve Pate 1...876 
 C++ Patterns 3...858 
 Assembler...845 
 Ulrich Drepper...838 
 DevFS...779 
 MySQL & PosgreSQL...761 
 Стивенс 9...752 
 
  01.01.2024 : 3621733 посещений 

iakovlev.org

Linux 2.6.9 Scheduler







Структура runqueue определена в kernel/sched.c

 struct runqueue {
 	spinlock_t lock;
 	unsigned long nr_running;
 	unsigned long cpu_load;
 	unsigned long long nr_switches;
 	unsigned long expired_timestamp, nr_uninterruptible;
 	unsigned long long timestamp_last_tick;
 	task_t *curr, *idle;
 	struct mm_struct *prev_mm;
 	prio_array_t *active, *expired, arrays[2];
 	int best_expired_prio;
 	atomic_t nr_iowait;
 	struct sched_domain *sd;
 	int active_balance;
 	int push_cpu;
 	task_t *migration_thread;
 	struct list_head migration_queue;
 	
 };
 
spinlock_t lock;
- блокировщик и "телохранитель" очереди процессов. Только один процесс может модифицировать runqueue .
unsigned long nr_running;
- порядковый номер задачи в очереди.
unsigned long cpu_load;
- загрузка процессора
unsigned long long nr_switches;
- время с последнего переключения приоритета
unsigned long  nr_uninterruptible;
- число задач , не имеющих прерываний
unsigned long long timestamp_last_tick;
- время последнего scheduler tick
task_t *curr;
- указатель на текущий процесс
task_t *idle;
- указатель на "пустышку"-процесс
struct mm_struct *prev_mm;
- указатель на виртуальную память предыдущего процесса
prio_array_t *active;
- массив приоритетных задач
prio_array_t *expired;
- массив задач с просроченным временем
int best_expired_prio;
- наивысший приоритет для всех задач
atomic_t nr_iowait;
- число задач в очереди , ждущих I/O
struct sched_domain *sd;
- домен , которому принадлежит очередь
int active_balance;
- балансировка очереди
int push_cpu;
- id процессора
	struct list_head migration_queue;
- список задач для миграции на много-процессорной системе

Блокировка

Только один процесс может блокировать очередь в данный момент времени. Функция для получения 2-х последовательных блокировок - double_rq_lock(rq1, rq2) , и ее обратный аналог - double_rq_unlock(rq1, rq2). Сама блокировка - task_rq_lock(task, &flags).

Массивы приоритетов

Планировщик всегда выполняет задачу с наивысшим приоритетом. Если несколько задач имеют наивысший одинаковый приоритет , то вступает в силу т.н. алгоритм round-robin . Имеются 2 массива - active и expired - для 2-х категорий задач.

unsigned int nr_active - число задач в таком массиве

unsigned long bitmap[BITMAP_SIZE] - битовый массив приоритетов задач в таком массиве задач. Этот битовый массив позволяет оптимизировать поиск приоритетов с помощью вызова __ffs().

struct list_head queue[MAX_PRIO] - список массивов. Каждый массив включает задачи со своим уровнем приоритета.

timeslice - время , которое отводится процессу на выполнение. Каждый приоритет - их всего 140 - имеет свой массив. После того как задача внутри такого массива получила шанс на выполнение и использовала его , она перемещается на вершину этого списка .

После того как timeslice заканчивается , задача удаляется из active priority array и перемещается в expired priority array. Когда все задачи окажутся перемещенными в expired priority array, происходит своппинг указателей active priority array и expired priority array.

Задачи имеют статический приоритет , который колеблется в пределах от -20 до 19. Чем выше это число , тем ниже приоритет. Любая задача начинает свою работу с нулевого приоритета , но потом он может быть изменен системным вызовом nice(). Статический приоритет хранится в static_prio. Задачи также имеют динамический приоритет , который хранится в prio

Когда задача выходит из спячки , время засыпания прибавляется к sleep_avg. Время , в течение которого процесс выполняется , вычитается из sleep_avg. Чем выше sleep_avg , тем выше динамический приоритет у задачи.

Когда форкается новый процесс , функция wake_up_forked_thread() уменьшает sleep_avg для родителя и потомка. Это делается для того , чтобы не произошло подавления со стороны более интерактивного процесса.

Каждую микросекунду срабатывает прерывание таймера - scheduler_tick(). Это событие порождает перемещение задач из expired array в active array. Это улучшает общую интерактивность и ротацию задач в системе.

Каждый процесс имеет переменную - interactive_credit. Чем больше спит процесс , тем выше это значение. Если это значение больше 100 , то это высокий интерактивный приоритет.

Задачи спят по-многим причинам - иногда они могут ожидать каких-то событий от устройств , иногда это причины программные , иногда из-за блокировки и т.д. Во время спячки они либо могут немедленно реагировать на внешние сигналы , либо нет - говорят , что они находятся в прерываемом либо в непрерываемом состоянии.

Waitqueue - очередь , в которой спящие задачи ожидают события . Процесс ухода в спячку порождает следующие атомарные события :

  1 Генерится DECLARE_WAIYQUEUE()
  2 Вызывается add_wait_queue()
  3 Задача маркируется с помощью TASK_INTERRUPTIBLE либо TASK_UNINTERRUPTIBLE
  4 Вызывается цикл schedule()
  5 Вызывается remove_wait_queue()
  
 

shedule() - главная функция шедулятора . Она переключает задачу и запускает ее. sheduler_tick() играет роль часового механизма, проверяя статус текущей задачи и выполняя балансировку очереди . Функция shedule() каждый раз проверяет время выполнения текущей задачи. Это время уменьшается , если выполняемая задача имеет высокий interactive credit. Далее , если функция получает сигнал прерывания от ядра для какой-то задачи , эта задача получает статус TASK_RUNNING . Далее , ищется следующая задача , если она есть в очереди на выполнение . Если таковых нет , происходит балансировка выполняемых задач .


 Файл kernel/sched.c :
 
 /*
  * If a task is 'interactive' then we reinsert it in the active
  * array after it has expired its current timeslice. (it will not
  * continue to run immediately, it will still roundrobin with
  * other interactive tasks.)
  *
  * This part scales the interactivity limit depending on niceness.
  *
  * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
  * Here are a few examples of different nice levels:
  *
  *  TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
  *  TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
  *  TASK_INTERACTIVE(  0): [1,1,1,1,0,0,0,0,0,0,0]
  *  TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
  *  TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
  *
  * (the X axis represents the possible -5 ... 0 ... +5 dynamic
  *  priority range a task can explore, a value of '1' means the
  *  task is rated interactive.)
  *
  * Ie. nice +19 tasks can never get 'interactive' enough to be
  * reinserted into the active array. And only heavily CPU-hog nice -20
  * tasks will be expired. Default nice 0 tasks are somewhere between,
  * it takes some effort for them to get interactive, but it's not
  * too hard.
  */
 
 
 /*
  * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
  * to time slice values: [800ms ... 100ms ... 5ms]
  *
  * The higher a thread's priority, the bigger timeslices
  * it gets during one round of execution. But even the lowest
  * priority thread gets MIN_TIMESLICE worth of execution time.
  */
 
 #define SCALE_PRIO(x, prio) \
 	max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
 
 static unsigned int task_timeslice(task_t *p)
 {
 	if (p->static_prio < NICE_TO_PRIO(0))
 		return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
 	else
 		return SCALE_PRIO(DEF_TIMESLICE, p->static_prio);
 }
 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran)	\
 				< (long long) (sd)->cache_hot_time)
 
 enum idle_type
 {
 	IDLE,
 	NOT_IDLE,
 	NEWLY_IDLE,
 	MAX_IDLE_TYPES
 };
 
 struct sched_domain;
 
 /*
  * These are the runqueue data structures:
  */
 
 #define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
 
 typedef struct runqueue runqueue_t;
 
 struct prio_array {
 	unsigned int nr_active;
 	unsigned long bitmap[BITMAP_SIZE];
 	struct list_head queue[MAX_PRIO];
 };
 
 /*
  * This is the main, per-CPU runqueue data structure.
  *
  * Locking rule: those places that want to lock multiple runqueues
  * (such as the load balancing or the thread migration code), lock
  * acquire operations must be ordered by ascending &runqueue.
  */
 struct runqueue {
 	spinlock_t lock;
 
 	/*
 	 * nr_running and cpu_load should be in the same cacheline because
 	 * remote CPUs use both these fields when doing load calculation.
 	 */
 	unsigned long nr_running;
 #ifdef CONFIG_SMP
 	unsigned long cpu_load;
 #endif
 	unsigned long long nr_switches;
 	unsigned long expired_timestamp, nr_uninterruptible;
 	unsigned long long timestamp_last_tick;
 	task_t *curr, *idle;
 	struct mm_struct *prev_mm;
 	prio_array_t *active, *expired, arrays[2];
 	int best_expired_prio;
 	atomic_t nr_iowait;
 
 #ifdef CONFIG_SMP
 	struct sched_domain *sd;
 
 	/* For active balancing */
 	int active_balance;
 	int push_cpu;
 
 	task_t *migration_thread;
 	struct list_head migration_queue;
 #endif
 
 #ifdef CONFIG_SCHEDSTATS
 	/* latency stats */
 	struct sched_info rq_sched_info;
 
 	/* sys_sched_yield() stats */
 	unsigned long yld_exp_empty;
 	unsigned long yld_act_empty;
 	unsigned long yld_both_empty;
 	unsigned long yld_cnt;
 
 	/* schedule() stats */
 	unsigned long sched_noswitch;
 	unsigned long sched_switch;
 	unsigned long sched_cnt;
 	unsigned long sched_goidle;
 
 	/* pull_task() stats */
 	unsigned long pt_gained[MAX_IDLE_TYPES];
 	unsigned long pt_lost[MAX_IDLE_TYPES];
 
 	/* active_load_balance() stats */
 	unsigned long alb_cnt;
 	unsigned long alb_lost;
 	unsigned long alb_gained;
 	unsigned long alb_failed;
 
 	/* try_to_wake_up() stats */
 	unsigned long ttwu_cnt;
 	unsigned long ttwu_attempts;
 	unsigned long ttwu_moved;
 
 	/* wake_up_new_task() stats */
 	unsigned long wunt_cnt;
 	unsigned long wunt_moved;
 
 	/* sched_migrate_task() stats */
 	unsigned long smt_cnt;
 
 	/* sched_balance_exec() stats */
 	unsigned long sbe_cnt;
 #endif
 };
 
 static DEFINE_PER_CPU(struct runqueue, runqueues);
 
 /*
  * sched-domains (multiprocessor balancing) declarations:
  */
 #ifdef CONFIG_SMP
 #define SCHED_LOAD_SCALE	128UL	/* increase resolution of load */
 
 #define SD_BALANCE_NEWIDLE	1	/* Balance when about to become idle */
 #define SD_BALANCE_EXEC		2	/* Balance on exec */
 #define SD_WAKE_IDLE		4	/* Wake to idle CPU on task wakeup */
 #define SD_WAKE_AFFINE		8	/* Wake task to waking CPU */
 #define SD_WAKE_BALANCE		16	/* Perform balancing at task wakeup */
 #define SD_SHARE_CPUPOWER	32	/* Domain members share cpu power */
 
 struct sched_group {
 	struct sched_group *next;	/* Must be a circular list */
 	cpumask_t cpumask;
 
 	/*
 	 * CPU power of this group, SCHED_LOAD_SCALE being max power for a
 	 * single CPU. This should be read only (except for setup). Although
 	 * it will need to be written to at cpu hot(un)plug time, perhaps the
 	 * cpucontrol semaphore will provide enough exclusion?
 	 */
 	unsigned long cpu_power;
 };
 
 struct sched_domain {
 	/* These fields must be setup */
 	struct sched_domain *parent;	/* top domain must be null terminated */
 	struct sched_group *groups;	/* the balancing groups of the domain */
 	cpumask_t span;			/* span of all CPUs in this domain */
 	unsigned long min_interval;	/* Minimum balance interval ms */
 	unsigned long max_interval;	/* Maximum balance interval ms */
 	unsigned int busy_factor;	/* less balancing by factor if busy */
 	unsigned int imbalance_pct;	/* No balance until over watermark */
 	unsigned long long cache_hot_time; /* Task considered cache hot (ns) */
 	unsigned int cache_nice_tries;	/* Leave cache hot tasks for # tries */
 	unsigned int per_cpu_gain;	/* CPU % gained by adding domain cpus */
 	int flags;			/* See SD_* */
 
 	/* Runtime fields. */
 	unsigned long last_balance;	/* init to jiffies. units in jiffies */
 	unsigned int balance_interval;	/* initialise to 1. units in ms. */
 	unsigned int nr_balance_failed; /* initialise to 0 */
 
 #ifdef CONFIG_SCHEDSTATS
 	/* load_balance() stats */
 	unsigned long lb_cnt[MAX_IDLE_TYPES];
 	unsigned long lb_failed[MAX_IDLE_TYPES];
 	unsigned long lb_imbalance[MAX_IDLE_TYPES];
 	unsigned long lb_nobusyg[MAX_IDLE_TYPES];
 	unsigned long lb_nobusyq[MAX_IDLE_TYPES];
 
 	/* sched_balance_exec() stats */
 	unsigned long sbe_attempts;
 	unsigned long sbe_pushed;
 
 	/* try_to_wake_up() stats */
 	unsigned long ttwu_wake_affine;
 	unsigned long ttwu_wake_balance;
 #endif
 };
 
 #ifndef ARCH_HAS_SCHED_TUNE
 #ifdef CONFIG_SCHED_SMT
 #define ARCH_HAS_SCHED_WAKE_IDLE
 /* Common values for SMT siblings */
 #define SD_SIBLING_INIT (struct sched_domain) {		\
 	.span			= CPU_MASK_NONE,	\
 	.parent			= NULL,			\
 	.groups			= NULL,			\
 	.min_interval		= 1,			\
 	.max_interval		= 2,			\
 	.busy_factor		= 8,			\
 	.imbalance_pct		= 110,			\
 	.cache_hot_time		= 0,			\
 	.cache_nice_tries	= 0,			\
 	.per_cpu_gain		= 25,			\
 	.flags			= SD_BALANCE_NEWIDLE	\
 				| SD_BALANCE_EXEC	\
 				| SD_WAKE_AFFINE	\
 				| SD_WAKE_IDLE		\
 				| SD_SHARE_CPUPOWER,	\
 	.last_balance		= jiffies,		\
 	.balance_interval	= 1,			\
 	.nr_balance_failed	= 0,			\
 }
 #endif
 
 /* Common values for CPUs */
 #define SD_CPU_INIT (struct sched_domain) {		\
 	.span			= CPU_MASK_NONE,	\
 	.parent			= NULL,			\
 	.groups			= NULL,			\
 	.min_interval		= 1,			\
 	.max_interval		= 4,			\
 	.busy_factor		= 64,			\
 	.imbalance_pct		= 125,			\
 	.cache_hot_time		= cache_decay_ticks*1000000 ? : (5*1000000/2),\
 	.cache_nice_tries	= 1,			\
 	.per_cpu_gain		= 100,			\
 	.flags			= SD_BALANCE_NEWIDLE	\
 				| SD_BALANCE_EXEC	\
 				| SD_WAKE_AFFINE	\
 				| SD_WAKE_BALANCE,	\
 	.last_balance		= jiffies,		\
 	.balance_interval	= 1,			\
 	.nr_balance_failed	= 0,			\
 }
 
 /* Arch can override this macro in processor.h */
 #if defined(CONFIG_NUMA) && !defined(SD_NODE_INIT)
 #define SD_NODE_INIT (struct sched_domain) {		\
 	.span			= CPU_MASK_NONE,	\
 	.parent			= NULL,			\
 	.groups			= NULL,			\
 	.min_interval		= 8,			\
 	.max_interval		= 32,			\
 	.busy_factor		= 32,			\
 	.imbalance_pct		= 125,			\
 	.cache_hot_time		= (10*1000000),		\
 	.cache_nice_tries	= 1,			\
 	.per_cpu_gain		= 100,			\
 	.flags			= SD_BALANCE_EXEC	\
 				| SD_WAKE_BALANCE,	\
 	.last_balance		= jiffies,		\
 	.balance_interval	= 1,			\
 	.nr_balance_failed	= 0,			\
 }
 #endif
 #endif /* ARCH_HAS_SCHED_TUNE */
 #endif
 
 
 #define for_each_domain(cpu, domain) \
 	for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
 
 #define cpu_rq(cpu)		(&per_cpu(runqueues, (cpu)))
 #define this_rq()		(&__get_cpu_var(runqueues))
 #define task_rq(p)		cpu_rq(task_cpu(p))
 #define cpu_curr(cpu)		(cpu_rq(cpu)->curr)
 
 /*
  * Default context-switch locking:
  */
 #ifndef prepare_arch_switch
 # define prepare_arch_switch(rq, next)	do { } while (0)
 # define finish_arch_switch(rq, next)	spin_unlock_irq(&(rq)->lock)
 # define task_running(rq, p)		((rq)->curr == (p))
 #endif
 
 /*
  * task_rq_lock - lock the runqueue a given task resides on and disable
  * interrupts.  Note the ordering: we can safely lookup the task_rq without
  * explicitly disabling preemption.
  */
 static runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
 {
 	struct runqueue *rq;
 
 repeat_lock_task:
 	local_irq_save(*flags);
 	rq = task_rq(p);
 	spin_lock(&rq->lock);
 	if (unlikely(rq != task_rq(p))) {
 		spin_unlock_irqrestore(&rq->lock, *flags);
 		goto repeat_lock_task;
 	}
 	return rq;
 }
 
 static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
 {
 	spin_unlock_irqrestore(&rq->lock, *flags);
 }
 
 #ifdef CONFIG_SCHEDSTATS
 /*
  * bump this up when changing the output format or the meaning of an existing
  * format, so that tools can adapt (or abort)
  */
 #define SCHEDSTAT_VERSION 10
 
 static int show_schedstat(struct seq_file *seq, void *v)
 {
 	int cpu;
 	enum idle_type itype;
 
 	seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
 	seq_printf(seq, "timestamp %lu\n", jiffies);
 	for_each_online_cpu(cpu) {
 		runqueue_t *rq = cpu_rq(cpu);
 #ifdef CONFIG_SMP
 		struct sched_domain *sd;
 		int dcnt = 0;
 #endif
 
 		/* runqueue-specific stats */
 		seq_printf(seq,
 		    "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu "
 		    "%lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
 		    cpu, rq->yld_both_empty,
 		    rq->yld_act_empty, rq->yld_exp_empty,
 		    rq->yld_cnt, rq->sched_noswitch,
 		    rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
 		    rq->alb_cnt, rq->alb_gained, rq->alb_lost,
 		    rq->alb_failed,
 		    rq->ttwu_cnt, rq->ttwu_moved, rq->ttwu_attempts,
 		    rq->wunt_cnt, rq->wunt_moved,
 		    rq->smt_cnt, rq->sbe_cnt, rq->rq_sched_info.cpu_time,
 		    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
 
 		for (itype = IDLE; itype < MAX_IDLE_TYPES; itype++)
 			seq_printf(seq, " %lu %lu", rq->pt_gained[itype],
 						    rq->pt_lost[itype]);
 		seq_printf(seq, "\n");
 
 #ifdef CONFIG_SMP
 		/* domain-specific stats */
 		for_each_domain(cpu, sd) {
 			char mask_str[NR_CPUS];
 
 			cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
 			seq_printf(seq, "domain%d %s", dcnt++, mask_str);
 			for (itype = IDLE; itype < MAX_IDLE_TYPES; itype++) {
 				seq_printf(seq, " %lu %lu %lu %lu %lu",
 				    sd->lb_cnt[itype],
 				    sd->lb_failed[itype],
 				    sd->lb_imbalance[itype],
 				    sd->lb_nobusyq[itype],
 				    sd->lb_nobusyg[itype]);
 			}
 			seq_printf(seq, " %lu %lu %lu %lu\n",
 			    sd->sbe_pushed, sd->sbe_attempts,
 			    sd->ttwu_wake_affine, sd->ttwu_wake_balance);
 		}
 #endif
 	}
 	return 0;
 }
 
 static int schedstat_open(struct inode *inode, struct file *file)
 {
 	unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
 	char *buf = kmalloc(size, GFP_KERNEL);
 	struct seq_file *m;
 	int res;
 
 	if (!buf)
 		return -ENOMEM;
 	res = single_open(file, show_schedstat, NULL);
 	if (!res) {
 		m = file->private_data;
 		m->buf = buf;
 		m->size = size;
 	} else
 		kfree(buf);
 	return res;
 }
 
 struct file_operations proc_schedstat_operations = {
 	.open    = schedstat_open,
 	.read    = seq_read,
 	.llseek  = seq_lseek,
 	.release = single_release,
 };
 
 # define schedstat_inc(rq, field)	rq->field++;
 # define schedstat_add(rq, field, amt)	rq->field += amt;
 #else /* !CONFIG_SCHEDSTATS */
 # define schedstat_inc(rq, field)	do { } while (0);
 # define schedstat_add(rq, field, amt)	do { } while (0);
 #endif
 
 /*
  * rq_lock - lock a given runqueue and disable interrupts.
  */
 static runqueue_t *this_rq_lock(void)
 {
 	runqueue_t *rq;
 
 	local_irq_disable();
 	rq = this_rq();
 	spin_lock(&rq->lock);
 
 	return rq;
 }
 
 static inline void rq_unlock(runqueue_t *rq)
 {
 	spin_unlock_irq(&rq->lock);
 }
 
 #ifdef CONFIG_SCHEDSTATS
 /*
  * Called when a process is dequeued from the active array and given
  * the cpu.  We should note that with the exception of interactive
  * tasks, the expired queue will become the active queue after the active
  * queue is empty, without explicitly dequeuing and requeuing tasks in the
  * expired queue.  (Interactive tasks may be requeued directly to the
  * active queue, thus delaying tasks in the expired queue from running;
  * see scheduler_tick()).
  *
  * This function is only called from sched_info_arrive(), rather than
  * dequeue_task(). Even though a task may be queued and dequeued multiple
  * times as it is shuffled about, we're really interested in knowing how
  * long it was from the *first* time it was queued to the time that it
  * finally hit a cpu.
  */
 static inline void sched_info_dequeued(task_t *t)
 {
 	t->sched_info.last_queued = 0;
 }
 
 /*
  * Called when a task finally hits the cpu.  We can now calculate how
  * long it was waiting to run.  We also note when it began so that we
  * can keep stats on how long its timeslice is.
  */
 static inline void sched_info_arrive(task_t *t)
 {
 	unsigned long now = jiffies, diff = 0;
 	struct runqueue *rq = task_rq(t);
 
 	if (t->sched_info.last_queued)
 		diff = now - t->sched_info.last_queued;
 	sched_info_dequeued(t);
 	t->sched_info.run_delay += diff;
 	t->sched_info.last_arrival = now;
 	t->sched_info.pcnt++;
 
 	if (!rq)
 		return;
 
 	rq->rq_sched_info.run_delay += diff;
 	rq->rq_sched_info.pcnt++;
 }
 
 /*
  * Called when a process is queued into either the active or expired
  * array.  The time is noted and later used to determine how long we
  * had to wait for us to reach the cpu.  Since the expired queue will
  * become the active queue after active queue is empty, without dequeuing
  * and requeuing any tasks, we are interested in queuing to either. It
  * is unusual but not impossible for tasks to be dequeued and immediately
  * requeued in the same or another array: this can happen in sched_yield(),
  * set_user_nice(), and even load_balance() as it moves tasks from runqueue
  * to runqueue.
  *
  * This function is only called from enqueue_task(), but also only updates
  * the timestamp if it is already not set.  It's assumed that
  * sched_info_dequeued() will clear that stamp when appropriate.
  */
 static inline void sched_info_queued(task_t *t)
 {
 	if (!t->sched_info.last_queued)
 		t->sched_info.last_queued = jiffies;
 }
 
 /*
  * Called when a process ceases being the active-running process, either
  * voluntarily or involuntarily.  Now we can calculate how long we ran.
  */
 static inline void sched_info_depart(task_t *t)
 {
 	struct runqueue *rq = task_rq(t);
 	unsigned long diff = jiffies - t->sched_info.last_arrival;
 
 	t->sched_info.cpu_time += diff;
 
 	if (rq)
 		rq->rq_sched_info.cpu_time += diff;
 }
 
 /*
  * Called when tasks are switched involuntarily due, typically, to expiring
  * their time slice.  (This may also be called when switching to or from
  * the idle task.)  We are only called when prev != next.
  */
 static inline void sched_info_switch(task_t *prev, task_t *next)
 {
 	struct runqueue *rq = task_rq(prev);
 
 	/*
 	 * prev now departs the cpu.  It's not interesting to record
 	 * stats about how efficient we were at scheduling the idle
 	 * process, however.
 	 */
 	if (prev != rq->idle)
 		sched_info_depart(prev);
 
 	if (next != rq->idle)
 		sched_info_arrive(next);
 }
 #else
 #define sched_info_queued(t)		do { } while (0)
 #define sched_info_switch(t, next)	do { } while (0)
 #endif /* CONFIG_SCHEDSTATS */
 
 /*
  * Adding/removing a task to/from a priority array:
  */
 static void dequeue_task(struct task_struct *p, prio_array_t *array)
 {
 	array->nr_active--;
 	list_del(&p->run_list);
 	if (list_empty(array->queue + p->prio))
 		__clear_bit(p->prio, array->bitmap);
 }
 
 static void enqueue_task(struct task_struct *p, prio_array_t *array)
 {
 	sched_info_queued(p);
 	list_add_tail(&p->run_list, array->queue + p->prio);
 	__set_bit(p->prio, array->bitmap);
 	array->nr_active++;
 	p->array = array;
 }
 
 /*
  * Used by the migration code - we pull tasks from the head of the
  * remote queue so we want these tasks to show up at the head of the
  * local queue:
  */
 static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array)
 {
 	list_add(&p->run_list, array->queue + p->prio);
 	__set_bit(p->prio, array->bitmap);
 	array->nr_active++;
 	p->array = array;
 }
 
 /*
  * effective_prio - return the priority that is based on the static
  * priority but is modified by bonuses/penalties.
  *
  * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
  * into the -5 ... 0 ... +5 bonus/penalty range.
  *
  * We use 25% of the full 0...39 priority range so that:
  *
  * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
  * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
  *
  * Both properties are important to certain workloads.
  */
 static int effective_prio(task_t *p)
 {
 	int bonus, prio;
 
 	if (rt_task(p))
 		return p->prio;
 
 	bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
 
 	prio = p->static_prio - bonus;
 	if (prio < MAX_RT_PRIO)
 		prio = MAX_RT_PRIO;
 	if (prio > MAX_PRIO-1)
 		prio = MAX_PRIO-1;
 	return prio;
 }
 
 /*
  * __activate_task - move a task to the runqueue.
  */
 static inline void __activate_task(task_t *p, runqueue_t *rq)
 {
 	enqueue_task(p, rq->active);
 	rq->nr_running++;
 }
 
 /*
  * __activate_idle_task - move idle task to the _front_ of runqueue.
  */
 static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
 {
 	enqueue_task_head(p, rq->active);
 	rq->nr_running++;
 }
 
 static void recalc_task_prio(task_t *p, unsigned long long now)
 {
 	unsigned long long __sleep_time = now - p->timestamp;
 	unsigned long sleep_time;
 
 	if (__sleep_time > NS_MAX_SLEEP_AVG)
 		sleep_time = NS_MAX_SLEEP_AVG;
 	else
 		sleep_time = (unsigned long)__sleep_time;
 
 	if (likely(sleep_time > 0)) {
 		/*
 		 * User tasks that sleep a long time are categorised as
 		 * idle and will get just interactive status to stay active &
 		 * prevent them suddenly becoming cpu hogs and starving
 		 * other processes.
 		 */
 		if (p->mm && p->activated != -1 &&
 			sleep_time > INTERACTIVE_SLEEP(p)) {
 				p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
 						DEF_TIMESLICE);
 				if (!HIGH_CREDIT(p))
 					p->interactive_credit++;
 		} else {
 			/*
 			 * The lower the sleep avg a task has the more
 			 * rapidly it will rise with sleep time.
 			 */
 			sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1;
 
 			/*
 			 * Tasks with low interactive_credit are limited to
 			 * one timeslice worth of sleep avg bonus.
 			 */
 			if (LOW_CREDIT(p) &&
 			    sleep_time > JIFFIES_TO_NS(task_timeslice(p)))
 				sleep_time = JIFFIES_TO_NS(task_timeslice(p));
 
 			/*
 			 * Non high_credit tasks waking from uninterruptible
 			 * sleep are limited in their sleep_avg rise as they
 			 * are likely to be cpu hogs waiting on I/O
 			 */
 			if (p->activated == -1 && !HIGH_CREDIT(p) && p->mm) {
 				if (p->sleep_avg >= INTERACTIVE_SLEEP(p))
 					sleep_time = 0;
 				else if (p->sleep_avg + sleep_time >=
 						INTERACTIVE_SLEEP(p)) {
 					p->sleep_avg = INTERACTIVE_SLEEP(p);
 					sleep_time = 0;
 				}
 			}
 
 			/*
 			 * This code gives a bonus to interactive tasks.
 			 *
 			 * The boost works by updating the 'average sleep time'
 			 * value here, based on ->timestamp. The more time a
 			 * task spends sleeping, the higher the average gets -
 			 * and the higher the priority boost gets as well.
 			 */
 			p->sleep_avg += sleep_time;
 
 			if (p->sleep_avg > NS_MAX_SLEEP_AVG) {
 				p->sleep_avg = NS_MAX_SLEEP_AVG;
 				if (!HIGH_CREDIT(p))
 					p->interactive_credit++;
 			}
 		}
 	}
 
 	p->prio = effective_prio(p);
 }
 
 /*
  * activate_task - move a task to the runqueue and do priority recalculation
  *
  * Update all the scheduling statistics stuff. (sleep average
  * calculation, priority modifiers, etc.)
  */
 static void activate_task(task_t *p, runqueue_t *rq, int local)
 {
 	unsigned long long now;
 
 	now = sched_clock();
 #ifdef CONFIG_SMP
 	if (!local) {
 		/* Compensate for drifting sched_clock */
 		runqueue_t *this_rq = this_rq();
 		now = (now - this_rq->timestamp_last_tick)
 			+ rq->timestamp_last_tick;
 	}
 #endif
 
 	recalc_task_prio(p, now);
 
 	/*
 	 * This checks to make sure it's not an uninterruptible task
 	 * that is now waking up.
 	 */
 	if (!p->activated) {
 		/*
 		 * Tasks which were woken up by interrupts (ie. hw events)
 		 * are most likely of interactive nature. So we give them
 		 * the credit of extending their sleep time to the period
 		 * of time they spend on the runqueue, waiting for execution
 		 * on a CPU, first time around:
 		 */
 		if (in_interrupt())
 			p->activated = 2;
 		else {
 			/*
 			 * Normal first-time wakeups get a credit too for
 			 * on-runqueue time, but it will be weighted down:
 			 */
 			p->activated = 1;
 		}
 	}
 	p->timestamp = now;
 
 	__activate_task(p, rq);
 }
 
 /*
  * deactivate_task - remove a task from the runqueue.
  */
 static void deactivate_task(struct task_struct *p, runqueue_t *rq)
 {
 	rq->nr_running--;
 	if (p->state == TASK_UNINTERRUPTIBLE)
 		rq->nr_uninterruptible++;
 	dequeue_task(p, p->array);
 	p->array = NULL;
 }
 
 /*
  * resched_task - mark a task 'to be rescheduled now'.
  *
  * On UP this means the setting of the need_resched flag, on SMP it
  * might also involve a cross-CPU call to trigger the scheduler on
  * the target CPU.
  */
 #ifdef CONFIG_SMP
 static void resched_task(task_t *p)
 {
 	int need_resched, nrpolling;
 
 	BUG_ON(!spin_is_locked(&task_rq(p)->lock));
 
 	/* minimise the chance of sending an interrupt to poll_idle() */
 	nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
 	need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
 	nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
 
 	if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
 		smp_send_reschedule(task_cpu(p));
 }
 #else
 static inline void resched_task(task_t *p)
 {
 	set_tsk_need_resched(p);
 }
 #endif
 
 /**
  * task_curr - is this task currently executing on a CPU?
  * @p: the task in question.
  */
 inline int task_curr(const task_t *p)
 {
 	return cpu_curr(task_cpu(p)) == p;
 }
 
 #ifdef CONFIG_SMP
 enum request_type {
 	REQ_MOVE_TASK,
 	REQ_SET_DOMAIN,
 };
 
 typedef struct {
 	struct list_head list;
 	enum request_type type;
 
 	/* For REQ_MOVE_TASK */
 	task_t *task;
 	int dest_cpu;
 
 	/* For REQ_SET_DOMAIN */
 	struct sched_domain *sd;
 
 	struct completion done;
 } migration_req_t;
 
 /*
  * The task's runqueue lock must be held.
  * Returns true if you have to wait for migration thread.
  */
 static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
 {
 	runqueue_t *rq = task_rq(p);
 
 	/*
 	 * If the task is not on a runqueue (and not running), then
 	 * it is sufficient to simply update the task's cpu field.
 	 */
 	if (!p->array && !task_running(rq, p)) {
 		set_task_cpu(p, dest_cpu);
 		return 0;
 	}
 
 	init_completion(&req->done);
 	req->type = REQ_MOVE_TASK;
 	req->task = p;
 	req->dest_cpu = dest_cpu;
 	list_add(&req->list, &rq->migration_queue);
 	return 1;
 }
 
 /*
  * wait_task_inactive - wait for a thread to unschedule.
  *
  * The caller must ensure that the task *will* unschedule sometime soon,
  * else this function might spin for a *long* time. This function can't
  * be called with interrupts off, or it may introduce deadlock with
  * smp_call_function() if an IPI is sent by the same process we are
  * waiting to become inactive.
  */
 void wait_task_inactive(task_t * p)
 {
 	unsigned long flags;
 	runqueue_t *rq;
 	int preempted;
 
 repeat:
 	rq = task_rq_lock(p, &flags);
 	/* Must be off runqueue entirely, not preempted. */
 	if (unlikely(p->array)) {
 		/* If it's preempted, we yield.  It could be a while. */
 		preempted = !task_running(rq, p);
 		task_rq_unlock(rq, &flags);
 		cpu_relax();
 		if (preempted)
 			yield();
 		goto repeat;
 	}
 	task_rq_unlock(rq, &flags);
 }
 
 /***
  * kick_process - kick a running thread to enter/exit the kernel
  * @p: the to-be-kicked thread
  *
  * Cause a process which is running on another CPU to enter
  * kernel-mode, without any delay. (to get signals handled.)
  */
 void kick_process(task_t *p)
 {
 	int cpu;
 
 	preempt_disable();
 	cpu = task_cpu(p);
 	if ((cpu != smp_processor_id()) && task_curr(p))
 		smp_send_reschedule(cpu);
 	preempt_enable();
 }
 
 EXPORT_SYMBOL_GPL(kick_process);
 
 /*
  * Return a low guess at the load of a migration-source cpu.
  *
  * We want to under-estimate the load of migration sources, to
  * balance conservatively.
  */
 static inline unsigned long source_load(int cpu)
 {
 	runqueue_t *rq = cpu_rq(cpu);
 	unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
 
 	return min(rq->cpu_load, load_now);
 }
 
 /*
  * Return a high guess at the load of a migration-target cpu
  */
 static inline unsigned long target_load(int cpu)
 {
 	runqueue_t *rq = cpu_rq(cpu);
 	unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
 
 	return max(rq->cpu_load, load_now);
 }
 
 #endif
 
 /*
  * wake_idle() is useful especially on SMT architectures to wake a
  * task onto an idle sibling if we would otherwise wake it onto a
  * busy sibling.
  *
  * Returns the CPU we should wake onto.
  */
 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
 static int wake_idle(int cpu, task_t *p)
 {
 	cpumask_t tmp;
 	runqueue_t *rq = cpu_rq(cpu);
 	struct sched_domain *sd;
 	int i;
 
 	if (idle_cpu(cpu))
 		return cpu;
 
 	sd = rq->sd;
 	if (!(sd->flags & SD_WAKE_IDLE))
 		return cpu;
 
 	cpus_and(tmp, sd->span, cpu_online_map);
 	cpus_and(tmp, tmp, p->cpus_allowed);
 
 	for_each_cpu_mask(i, tmp) {
 		if (idle_cpu(i))
 			return i;
 	}
 
 	return cpu;
 }
 #else
 static inline int wake_idle(int cpu, task_t *p)
 {
 	return cpu;
 }
 #endif
 
 /***
  * try_to_wake_up - wake up a thread
  * @p: the to-be-woken-up thread
  * @state: the mask of task states that can be woken
  * @sync: do a synchronous wakeup?
  *
  * Put it on the run-queue if it's not already there. The "current"
  * thread is always on the run-queue (except when the actual
  * re-schedule is in progress), and as such you're allowed to do
  * the simpler "current->state = TASK_RUNNING" to mark yourself
  * runnable without the overhead of this.
  *
  * returns failure only if the task is already active.
  */
 static int try_to_wake_up(task_t * p, unsigned int state, int sync)
 {
 	int cpu, this_cpu, success = 0;
 	unsigned long flags;
 	long old_state;
 	runqueue_t *rq;
 #ifdef CONFIG_SMP
 	unsigned long load, this_load;
 	struct sched_domain *sd;
 	int new_cpu;
 #endif
 
 	rq = task_rq_lock(p, &flags);
 	schedstat_inc(rq, ttwu_cnt);
 	old_state = p->state;
 	if (!(old_state & state))
 		goto out;
 
 	if (p->array)
 		goto out_running;
 
 	cpu = task_cpu(p);
 	this_cpu = smp_processor_id();
 
 #ifdef CONFIG_SMP
 	if (unlikely(task_running(rq, p)))
 		goto out_activate;
 
 	new_cpu = cpu;
 
 	if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
 		goto out_set_cpu;
 
 	load = source_load(cpu);
 	this_load = target_load(this_cpu);
 
 	/*
 	 * If sync wakeup then subtract the (maximum possible) effect of
 	 * the currently running task from the load of the current CPU:
 	 */
 	if (sync)
 		this_load -= SCHED_LOAD_SCALE;
 
 	/* Don't pull the task off an idle CPU to a busy one */
 	if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2)
 		goto out_set_cpu;
 
 	new_cpu = this_cpu; /* Wake to this CPU if we can */
 
 	/*
 	 * Scan domains for affine wakeup and passive balancing
 	 * possibilities.
 	 */
 	for_each_domain(this_cpu, sd) {
 		unsigned int imbalance;
 		/*
 		 * Start passive balancing when half the imbalance_pct
 		 * limit is reached.
 		 */
 		imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;
 
 		if ((sd->flags & SD_WAKE_AFFINE) &&
 				!task_hot(p, rq->timestamp_last_tick, sd)) {
 			/*
 			 * This domain has SD_WAKE_AFFINE and p is cache cold
 			 * in this domain.
 			 */
 			if (cpu_isset(cpu, sd->span)) {
 				schedstat_inc(sd, ttwu_wake_affine);
 				goto out_set_cpu;
 			}
 		} else if ((sd->flags & SD_WAKE_BALANCE) &&
 				imbalance*this_load <= 100*load) {
 			/*
 			 * This domain has SD_WAKE_BALANCE and there is
 			 * an imbalance.
 			 */
 			if (cpu_isset(cpu, sd->span)) {
 				schedstat_inc(sd, ttwu_wake_balance);
 				goto out_set_cpu;
 			}
 		}
 	}
 
 	new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
 out_set_cpu:
 	schedstat_inc(rq, ttwu_attempts);
 	new_cpu = wake_idle(new_cpu, p);
 	if (new_cpu != cpu && cpu_isset(new_cpu, p->cpus_allowed)) {
 		schedstat_inc(rq, ttwu_moved);
 		set_task_cpu(p, new_cpu);
 		task_rq_unlock(rq, &flags);
 		/* might preempt at this point */
 		rq = task_rq_lock(p, &flags);
 		old_state = p->state;
 		if (!(old_state & state))
 			goto out;
 		if (p->array)
 			goto out_running;
 
 		this_cpu = smp_processor_id();
 		cpu = task_cpu(p);
 	}
 
 out_activate:
 #endif /* CONFIG_SMP */
 	if (old_state == TASK_UNINTERRUPTIBLE) {
 		rq->nr_uninterruptible--;
 		/*
 		 * Tasks on involuntary sleep don't earn
 		 * sleep_avg beyond just interactive state.
 		 */
 		p->activated = -1;
 	}
 
 	/*
 	 * Sync wakeups (i.e. those types of wakeups where the waker
 	 * has indicated that it will leave the CPU in short order)
 	 * don't trigger a preemption, if the woken up task will run on
 	 * this cpu. (in this case the 'I will reschedule' promise of
 	 * the waker guarantees that the freshly woken up task is going
 	 * to be considered on this CPU.)
 	 */
 	activate_task(p, rq, cpu == this_cpu);
 	if (!sync || cpu != this_cpu) {
 		if (TASK_PREEMPTS_CURR(p, rq))
 			resched_task(rq->curr);
 	}
 	success = 1;
 
 out_running:
 	p->state = TASK_RUNNING;
 out:
 	task_rq_unlock(rq, &flags);
 
 	return success;
 }
 
 int fastcall wake_up_process(task_t * p)
 {
 	return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
 		       		 TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
 }
 
 EXPORT_SYMBOL(wake_up_process);
 
 int fastcall wake_up_state(task_t *p, unsigned int state)
 {
 	return try_to_wake_up(p, state, 0);
 }
 
 #ifdef CONFIG_SMP
 static int find_idlest_cpu(struct task_struct *p, int this_cpu,
 			   struct sched_domain *sd);
 #endif
 
 /*
  * Perform scheduler related setup for a newly forked process p.
  * p is forked by current.
  */
 void fastcall sched_fork(task_t *p)
 {
 	/*
 	 * We mark the process as running here, but have not actually
 	 * inserted it onto the runqueue yet. This guarantees that
 	 * nobody will actually run it, and a signal or other external
 	 * event cannot wake it up and insert it on the runqueue either.
 	 */
 	p->state = TASK_RUNNING;
 	INIT_LIST_HEAD(&p->run_list);
 	p->array = NULL;
 	spin_lock_init(&p->switch_lock);
 #ifdef CONFIG_SCHEDSTATS
 	memset(&p->sched_info, 0, sizeof(p->sched_info));
 #endif
 #ifdef CONFIG_PREEMPT
 	/*
 	 * During context-switch we hold precisely one spinlock, which
 	 * schedule_tail drops. (in the common case it's this_rq()->lock,
 	 * but it also can be p->switch_lock.) So we compensate with a count
 	 * of 1. Also, we want to start with kernel preemption disabled.
 	 */
 	p->thread_info->preempt_count = 1;
 #endif
 	/*
 	 * Share the timeslice between parent and child, thus the
 	 * total amount of pending timeslices in the system doesn't change,
 	 * resulting in more scheduling fairness.
 	 */
 	local_irq_disable();
 	p->time_slice = (current->time_slice + 1) >> 1;
 	/*
 	 * The remainder of the first timeslice might be recovered by
 	 * the parent if the child exits early enough.
 	 */
 	p->first_time_slice = 1;
 	current->time_slice >>= 1;
 	p->timestamp = sched_clock();
 	if (unlikely(!current->time_slice)) {
 		/*
 		 * This case is rare, it happens when the parent has only
 		 * a single jiffy left from its timeslice. Taking the
 		 * runqueue lock is not a problem.
 		 */
 		current->time_slice = 1;
 		preempt_disable();
 		scheduler_tick(0, 0);
 		local_irq_enable();
 		preempt_enable();
 	} else
 		local_irq_enable();
 }
 
 /*
  * wake_up_new_task - wake up a newly created task for the first time.
  *
  * This function will do some initial scheduler statistics housekeeping
  * that must be done for every newly created context, then puts the task
  * on the runqueue and wakes it.
  */
 void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags)
 {
 	unsigned long flags;
 	int this_cpu, cpu;
 	runqueue_t *rq, *this_rq;
 
 	rq = task_rq_lock(p, &flags);
 	cpu = task_cpu(p);
 	this_cpu = smp_processor_id();
 
 	BUG_ON(p->state != TASK_RUNNING);
 
 	schedstat_inc(rq, wunt_cnt);
 	/*
 	 * We decrease the sleep average of forking parents
 	 * and children as well, to keep max-interactive tasks
 	 * from forking tasks that are max-interactive. The parent
 	 * (current) is done further down, under its lock.
 	 */
 	p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
 		CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
 
 	p->interactive_credit = 0;
 
 	p->prio = effective_prio(p);
 
 	if (likely(cpu == this_cpu)) {
 		if (!(clone_flags & CLONE_VM)) {
 			/*
 			 * The VM isn't cloned, so we're in a good position to
 			 * do child-runs-first in anticipation of an exec. This
 			 * usually avoids a lot of COW overhead.
 			 */
 			if (unlikely(!current->array))
 				__activate_task(p, rq);
 			else {
 				p->prio = current->prio;
 				list_add_tail(&p->run_list, ¤t->run_list);
 				p->array = current->array;
 				p->array->nr_active++;
 				rq->nr_running++;
 			}
 			set_need_resched();
 		} else
 			/* Run child last */
 			__activate_task(p, rq);
 		/*
 		 * We skip the following code due to cpu == this_cpu
 	 	 *
 		 *   task_rq_unlock(rq, &flags);
 		 *   this_rq = task_rq_lock(current, &flags);
 		 */
 		this_rq = rq;
 	} else {
 		this_rq = cpu_rq(this_cpu);
 
 		/*
 		 * Not the local CPU - must adjust timestamp. This should
 		 * get optimised away in the !CONFIG_SMP case.
 		 */
 		p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
 					+ rq->timestamp_last_tick;
 		__activate_task(p, rq);
 		if (TASK_PREEMPTS_CURR(p, rq))
 			resched_task(rq->curr);
 
 		schedstat_inc(rq, wunt_moved);
 		/*
 		 * Parent and child are on different CPUs, now get the
 		 * parent runqueue to update the parent's ->sleep_avg:
 		 */
 		task_rq_unlock(rq, &flags);
 		this_rq = task_rq_lock(current, &flags);
 	}
 	current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
 		PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
 	task_rq_unlock(this_rq, &flags);
 }
 
 /*
  * Potentially available exiting-child timeslices are
  * retrieved here - this way the parent does not get
  * penalized for creating too many threads.
  *
  * (this cannot be used to 'generate' timeslices
  * artificially, because any timeslice recovered here
  * was given away by the parent in the first place.)
  */
 void fastcall sched_exit(task_t * p)
 {
 	unsigned long flags;
 	runqueue_t *rq;
 
 	/*
 	 * If the child was a (relative-) CPU hog then decrease
 	 * the sleep_avg of the parent as well.
 	 */
 	rq = task_rq_lock(p->parent, &flags);
 	if (p->first_time_slice) {
 		p->parent->time_slice += p->time_slice;
 		if (unlikely(p->parent->time_slice > task_timeslice(p)))
 			p->parent->time_slice = task_timeslice(p);
 	}
 	if (p->sleep_avg < p->parent->sleep_avg)
 		p->parent->sleep_avg = p->parent->sleep_avg /
 		(EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
 		(EXIT_WEIGHT + 1);
 	task_rq_unlock(rq, &flags);
 }
 
 /**
  * finish_task_switch - clean up after a task-switch
  * @prev: the thread we just switched away from.
  *
  * We enter this with the runqueue still locked, and finish_arch_switch()
  * will unlock it along with doing any other architecture-specific cleanup
  * actions.
  *
  * Note that we may have delayed dropping an mm in context_switch(). If
  * so, we finish that here outside of the runqueue lock.  (Doing it
  * with the lock held can cause deadlocks; see schedule() for
  * details.)
  */
 static void finish_task_switch(task_t *prev)
 {
 	runqueue_t *rq = this_rq();
 	struct mm_struct *mm = rq->prev_mm;
 	unsigned long prev_task_flags;
 
 	rq->prev_mm = NULL;
 
 	/*
 	 * A task struct has one reference for the use as "current".
 	 * If a task dies, then it sets TASK_ZOMBIE in tsk->state and calls
 	 * schedule one last time. The schedule call will never return,
 	 * and the scheduled task must drop that reference.
 	 * The test for TASK_ZOMBIE must occur while the runqueue locks are
 	 * still held, otherwise prev could be scheduled on another cpu, die
 	 * there before we look at prev->state, and then the reference would
 	 * be dropped twice.
 	 *		Manfred Spraul 
 	 */
 	prev_task_flags = prev->flags;
 	finish_arch_switch(rq, prev);
 	if (mm)
 		mmdrop(mm);
 	if (unlikely(prev_task_flags & PF_DEAD))
 		put_task_struct(prev);
 }
 
 /**
  * schedule_tail - first thing a freshly forked thread must call.
  * @prev: the thread we just switched away from.
  */
 asmlinkage void schedule_tail(task_t *prev)
 {
 	finish_task_switch(prev);
 
 	if (current->set_child_tid)
 		put_user(current->pid, current->set_child_tid);
 }
 
 /*
  * context_switch - switch to the new MM and the new
  * thread's register state.
  */
 static inline
 task_t * context_switch(runqueue_t *rq, task_t *prev, task_t *next)
 {
 	struct mm_struct *mm = next->mm;
 	struct mm_struct *oldmm = prev->active_mm;
 
 	if (unlikely(!mm)) {
 		next->active_mm = oldmm;
 		atomic_inc(&oldmm->mm_count);
 		enter_lazy_tlb(oldmm, next);
 	} else
 		switch_mm(oldmm, mm, next);
 
 	if (unlikely(!prev->mm)) {
 		prev->active_mm = NULL;
 		WARN_ON(rq->prev_mm);
 		rq->prev_mm = oldmm;
 	}
 
 	/* Here we just switch the register state and the stack. */
 	switch_to(prev, next, prev);
 
 	return prev;
 }
 
 /*
  * nr_running, nr_uninterruptible and nr_context_switches:
  *
  * externally visible scheduler statistics: current number of runnable
  * threads, current number of uninterruptible-sleeping threads, total
  * number of context switches performed since bootup.
  */
 unsigned long nr_running(void)
 {
 	unsigned long i, sum = 0;
 
 	for_each_online_cpu(i)
 		sum += cpu_rq(i)->nr_running;
 
 	return sum;
 }
 
 unsigned long nr_uninterruptible(void)
 {
 	unsigned long i, sum = 0;
 
 	for_each_cpu(i)
 		sum += cpu_rq(i)->nr_uninterruptible;
 
 	return sum;
 }
 
 unsigned long long nr_context_switches(void)
 {
 	unsigned long long i, sum = 0;
 
 	for_each_cpu(i)
 		sum += cpu_rq(i)->nr_switches;
 
 	return sum;
 }
 
 unsigned long nr_iowait(void)
 {
 	unsigned long i, sum = 0;
 
 	for_each_cpu(i)
 		sum += atomic_read(&cpu_rq(i)->nr_iowait);
 
 	return sum;
 }
 
 #ifdef CONFIG_SMP
 
 /*
  * double_rq_lock - safely lock two runqueues
  *
  * Note this does not disable interrupts like task_rq_lock,
  * you need to do so manually before calling.
  */
 static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
 {
 	if (rq1 == rq2)
 		spin_lock(&rq1->lock);
 	else {
 		if (rq1 < rq2) {
 			spin_lock(&rq1->lock);
 			spin_lock(&rq2->lock);
 		} else {
 			spin_lock(&rq2->lock);
 			spin_lock(&rq1->lock);
 		}
 	}
 }
 
 /*
  * double_rq_unlock - safely unlock two runqueues
  *
  * Note this does not restore interrupts like task_rq_unlock,
  * you need to do so manually after calling.
  */
 static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
 {
 	spin_unlock(&rq1->lock);
 	if (rq1 != rq2)
 		spin_unlock(&rq2->lock);
 }
 
 /*
  * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
  */
 static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
 {
 	if (unlikely(!spin_trylock(&busiest->lock))) {
 		if (busiest < this_rq) {
 			spin_unlock(&this_rq->lock);
 			spin_lock(&busiest->lock);
 			spin_lock(&this_rq->lock);
 		} else
 			spin_lock(&busiest->lock);
 	}
 }
 
 /*
  * find_idlest_cpu - find the least busy runqueue.
  */
 static int find_idlest_cpu(struct task_struct *p, int this_cpu,
 			   struct sched_domain *sd)
 {
 	unsigned long load, min_load, this_load;
 	int i, min_cpu;
 	cpumask_t mask;
 
 	min_cpu = UINT_MAX;
 	min_load = ULONG_MAX;
 
 	cpus_and(mask, sd->span, cpu_online_map);
 	cpus_and(mask, mask, p->cpus_allowed);
 
 	for_each_cpu_mask(i, mask) {
 		load = target_load(i);
 
 		if (load < min_load) {
 			min_cpu = i;
 			min_load = load;
 
 			/* break out early on an idle CPU: */
 			if (!min_load)
 				break;
 		}
 	}
 
 	/* add +1 to account for the new task */
 	this_load = source_load(this_cpu) + SCHED_LOAD_SCALE;
 
 	/*
 	 * Would with the addition of the new task to the
 	 * current CPU there be an imbalance between this
 	 * CPU and the idlest CPU?
 	 *
 	 * Use half of the balancing threshold - new-context is
 	 * a good opportunity to balance.
 	 */
 	if (min_load*(100 + (sd->imbalance_pct-100)/2) < this_load*100)
 		return min_cpu;
 
 	return this_cpu;
 }
 
 /*
  * If dest_cpu is allowed for this process, migrate the task to it.
  * This is accomplished by forcing the cpu_allowed mask to only
  * allow dest_cpu, which will force the cpu onto dest_cpu.  Then
  * the cpu_allowed mask is restored.
  */
 static void sched_migrate_task(task_t *p, int dest_cpu)
 {
 	migration_req_t req;
 	runqueue_t *rq;
 	unsigned long flags;
 
 	rq = task_rq_lock(p, &flags);
 	if (!cpu_isset(dest_cpu, p->cpus_allowed)
 	    || unlikely(cpu_is_offline(dest_cpu)))
 		goto out;
 
 	schedstat_inc(rq, smt_cnt);
 	/* force the process onto the specified CPU */
 	if (migrate_task(p, dest_cpu, &req)) {
 		/* Need to wait for migration thread (might exit: take ref). */
 		struct task_struct *mt = rq->migration_thread;
 		get_task_struct(mt);
 		task_rq_unlock(rq, &flags);
 		wake_up_process(mt);
 		put_task_struct(mt);
 		wait_for_completion(&req.done);
 		return;
 	}
 out:
 	task_rq_unlock(rq, &flags);
 }
 
 /*
  * sched_exec(): find the highest-level, exec-balance-capable
  * domain and try to migrate the task to the least loaded CPU.
  *
  * execve() is a valuable balancing opportunity, because at this point
  * the task has the smallest effective memory and cache footprint.
  */
 void sched_exec(void)
 {
 	struct sched_domain *tmp, *sd = NULL;
 	int new_cpu, this_cpu = get_cpu();
 
 	schedstat_inc(this_rq(), sbe_cnt);
 	/* Prefer the current CPU if there's only this task running */
 	if (this_rq()->nr_running <= 1)
 		goto out;
 
 	for_each_domain(this_cpu, tmp)
 		if (tmp->flags & SD_BALANCE_EXEC)
 			sd = tmp;
 
 	if (sd) {
 		schedstat_inc(sd, sbe_attempts);
 		new_cpu = find_idlest_cpu(current, this_cpu, sd);
 		if (new_cpu != this_cpu) {
 			schedstat_inc(sd, sbe_pushed);
 			put_cpu();
 			sched_migrate_task(current, new_cpu);
 			return;
 		}
 	}
 out:
 	put_cpu();
 }
 
 /*
  * pull_task - move a task from a remote runqueue to the local runqueue.
  * Both runqueues must be locked.
  */
 static inline
 void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
 	       runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
 {
 	dequeue_task(p, src_array);
 	src_rq->nr_running--;
 	set_task_cpu(p, this_cpu);
 	this_rq->nr_running++;
 	enqueue_task(p, this_array);
 	p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
 				+ this_rq->timestamp_last_tick;
 	/*
 	 * Note that idle threads have a prio of MAX_PRIO, for this test
 	 * to be always true for them.
 	 */
 	if (TASK_PREEMPTS_CURR(p, this_rq))
 		resched_task(this_rq->curr);
 }
 
 /*
  * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
  */
 static inline
 int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
 		     struct sched_domain *sd, enum idle_type idle)
 {
 	/*
 	 * We do not migrate tasks that are:
 	 * 1) running (obviously), or
 	 * 2) cannot be migrated to this CPU due to cpus_allowed, or
 	 * 3) are cache-hot on their current CPU.
 	 */
 	if (task_running(rq, p))
 		return 0;
 	if (!cpu_isset(this_cpu, p->cpus_allowed))
 		return 0;
 
 	/* Aggressive migration if we've failed balancing */
 	if (idle == NEWLY_IDLE ||
 			sd->nr_balance_failed < sd->cache_nice_tries) {
 		if (task_hot(p, rq->timestamp_last_tick, sd))
 			return 0;
 	}
 
 	return 1;
 }
 
 /*
  * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
  * as part of a balancing operation within "domain". Returns the number of
  * tasks moved.
  *
  * Called with both runqueues locked.
  */
 static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
 		      unsigned long max_nr_move, struct sched_domain *sd,
 		      enum idle_type idle)
 {
 	prio_array_t *array, *dst_array;
 	struct list_head *head, *curr;
 	int idx, pulled = 0;
 	task_t *tmp;
 
 	if (max_nr_move <= 0 || busiest->nr_running <= 1)
 		goto out;
 
 	/*
 	 * We first consider expired tasks. Those will likely not be
 	 * executed in the near future, and they are most likely to
 	 * be cache-cold, thus switching CPUs has the least effect
 	 * on them.
 	 */
 	if (busiest->expired->nr_active) {
 		array = busiest->expired;
 		dst_array = this_rq->expired;
 	} else {
 		array = busiest->active;
 		dst_array = this_rq->active;
 	}
 
 new_array:
 	/* Start searching at priority 0: */
 	idx = 0;
 skip_bitmap:
 	if (!idx)
 		idx = sched_find_first_bit(array->bitmap);
 	else
 		idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
 	if (idx >= MAX_PRIO) {
 		if (array == busiest->expired && busiest->active->nr_active) {
 			array = busiest->active;
 			dst_array = this_rq->active;
 			goto new_array;
 		}
 		goto out;
 	}
 
 	head = array->queue + idx;
 	curr = head->prev;
 skip_queue:
 	tmp = list_entry(curr, task_t, run_list);
 
 	curr = curr->prev;
 
 	if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) {
 		if (curr != head)
 			goto skip_queue;
 		idx++;
 		goto skip_bitmap;
 	}
 
 	/*
 	 * Right now, this is the only place pull_task() is called,
 	 * so we can safely collect pull_task() stats here rather than
 	 * inside pull_task().
 	 */
 	schedstat_inc(this_rq, pt_gained[idle]);
 	schedstat_inc(busiest, pt_lost[idle]);
 
 	pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
 	pulled++;
 
 	/* We only want to steal up to the prescribed number of tasks. */
 	if (pulled < max_nr_move) {
 		if (curr != head)
 			goto skip_queue;
 		idx++;
 		goto skip_bitmap;
 	}
 out:
 	return pulled;
 }
 
 /*
  * find_busiest_group finds and returns the busiest CPU group within the
  * domain. It calculates and returns the number of tasks which should be
  * moved to restore balance via the imbalance parameter.
  */
 static struct sched_group *
 find_busiest_group(struct sched_domain *sd, int this_cpu,
 		   unsigned long *imbalance, enum idle_type idle)
 {
 	struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
 	unsigned long max_load, avg_load, total_load, this_load, total_pwr;
 
 	max_load = this_load = total_load = total_pwr = 0;
 
 	do {
 		cpumask_t tmp;
 		unsigned long load;
 		int local_group;
 		int i, nr_cpus = 0;
 
 		local_group = cpu_isset(this_cpu, group->cpumask);
 
 		/* Tally up the load of all CPUs in the group */
 		avg_load = 0;
 		cpus_and(tmp, group->cpumask, cpu_online_map);
 		if (unlikely(cpus_empty(tmp)))
 			goto nextgroup;
 
 		for_each_cpu_mask(i, tmp) {
 			/* Bias balancing toward cpus of our domain */
 			if (local_group)
 				load = target_load(i);
 			else
 				load = source_load(i);
 
 			nr_cpus++;
 			avg_load += load;
 		}
 
 		if (!nr_cpus)
 			goto nextgroup;
 
 		total_load += avg_load;
 		total_pwr += group->cpu_power;
 
 		/* Adjust by relative CPU power of the group */
 		avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
 
 		if (local_group) {
 			this_load = avg_load;
 			this = group;
 			goto nextgroup;
 		} else if (avg_load > max_load) {
 			max_load = avg_load;
 			busiest = group;
 		}
 nextgroup:
 		group = group->next;
 	} while (group != sd->groups);
 
 	if (!busiest || this_load >= max_load)
 		goto out_balanced;
 
 	avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
 
 	if (this_load >= avg_load ||
 			100*max_load <= sd->imbalance_pct*this_load)
 		goto out_balanced;
 
 	/*
 	 * We're trying to get all the cpus to the average_load, so we don't
 	 * want to push ourselves above the average load, nor do we wish to
 	 * reduce the max loaded cpu below the average load, as either of these
 	 * actions would just result in more rebalancing later, and ping-pong
 	 * tasks around. Thus we look for the minimum possible imbalance.
 	 * Negative imbalances (*we* are more loaded than anyone else) will
 	 * be counted as no imbalance for these purposes -- we can't fix that
 	 * by pulling tasks to us.  Be careful of negative numbers as they'll
 	 * appear as very large values with unsigned longs.
 	 */
 	*imbalance = min(max_load - avg_load, avg_load - this_load);
 
 	/* How much load to actually move to equalise the imbalance */
 	*imbalance = (*imbalance * min(busiest->cpu_power, this->cpu_power))
 				/ SCHED_LOAD_SCALE;
 
 	if (*imbalance < SCHED_LOAD_SCALE - 1) {
 		unsigned long pwr_now = 0, pwr_move = 0;
 		unsigned long tmp;
 
 		if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
 			*imbalance = 1;
 			return busiest;
 		}
 
 		/*
 		 * OK, we don't have enough imbalance to justify moving tasks,
 		 * however we may be able to increase total CPU power used by
 		 * moving them.
 		 */
 
 		pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
 		pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
 		pwr_now /= SCHED_LOAD_SCALE;
 
 		/* Amount of load we'd subtract */
 		tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
 		if (max_load > tmp)
 			pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
 							max_load - tmp);
 
 		/* Amount of load we'd add */
 		tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
 		if (max_load < tmp)
 			tmp = max_load;
 		pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
 		pwr_move /= SCHED_LOAD_SCALE;
 
 		/* Move if we gain another 8th of a CPU worth of throughput */
 		if (pwr_move < pwr_now + SCHED_LOAD_SCALE / 8)
 			goto out_balanced;
 
 		*imbalance = 1;
 		return busiest;
 	}
 
 	/* Get rid of the scaling factor, rounding down as we divide */
 	*imbalance = (*imbalance + 1) / SCHED_LOAD_SCALE;
 
 	return busiest;
 
 out_balanced:
 	if (busiest && (idle == NEWLY_IDLE ||
 			(idle == IDLE && max_load > SCHED_LOAD_SCALE)) ) {
 		*imbalance = 1;
 		return busiest;
 	}
 
 	*imbalance = 0;
 	return NULL;
 }
 
 /*
  * find_busiest_queue - find the busiest runqueue among the cpus in group.
  */
 static runqueue_t *find_busiest_queue(struct sched_group *group)
 {
 	cpumask_t tmp;
 	unsigned long load, max_load = 0;
 	runqueue_t *busiest = NULL;
 	int i;
 
 	cpus_and(tmp, group->cpumask, cpu_online_map);
 	for_each_cpu_mask(i, tmp) {
 		load = source_load(i);
 
 		if (load > max_load) {
 			max_load = load;
 			busiest = cpu_rq(i);
 		}
 	}
 
 	return busiest;
 }
 
 /*
  * Check this_cpu to ensure it is balanced within domain. Attempt to move
  * tasks if there is an imbalance.
  *
  * Called with this_rq unlocked.
  */
 static int load_balance(int this_cpu, runqueue_t *this_rq,
 			struct sched_domain *sd, enum idle_type idle)
 {
 	struct sched_group *group;
 	runqueue_t *busiest;
 	unsigned long imbalance;
 	int nr_moved;
 
 	spin_lock(&this_rq->lock);
 	schedstat_inc(sd, lb_cnt[idle]);
 
 	group = find_busiest_group(sd, this_cpu, &imbalance, idle);
 	if (!group) {
 		schedstat_inc(sd, lb_nobusyg[idle]);
 		goto out_balanced;
 	}
 
 	busiest = find_busiest_queue(group);
 	if (!busiest) {
 		schedstat_inc(sd, lb_nobusyq[idle]);
 		goto out_balanced;
 	}
 
 	/*
 	 * This should be "impossible", but since load
 	 * balancing is inherently racy and statistical,
 	 * it could happen in theory.
 	 */
 	if (unlikely(busiest == this_rq)) {
 		WARN_ON(1);
 		goto out_balanced;
 	}
 
 	schedstat_add(sd, lb_imbalance[idle], imbalance);
 
 	nr_moved = 0;
 	if (busiest->nr_running > 1) {
 		/*
 		 * Attempt to move tasks. If find_busiest_group has found
 		 * an imbalance but busiest->nr_running <= 1, the group is
 		 * still unbalanced. nr_moved simply stays zero, so it is
 		 * correctly treated as an imbalance.
 		 */
 		double_lock_balance(this_rq, busiest);
 		nr_moved = move_tasks(this_rq, this_cpu, busiest,
 						imbalance, sd, idle);
 		spin_unlock(&busiest->lock);
 	}
 	spin_unlock(&this_rq->lock);
 
 	if (!nr_moved) {
 		schedstat_inc(sd, lb_failed[idle]);
 		sd->nr_balance_failed++;
 
 		if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
 			int wake = 0;
 
 			spin_lock(&busiest->lock);
 			if (!busiest->active_balance) {
 				busiest->active_balance = 1;
 				busiest->push_cpu = this_cpu;
 				wake = 1;
 			}
 			spin_unlock(&busiest->lock);
 			if (wake)
 				wake_up_process(busiest->migration_thread);
 
 			/*
 			 * We've kicked active balancing, reset the failure
 			 * counter.
 			 */
 			sd->nr_balance_failed = sd->cache_nice_tries;
 		}
 	} else
 		sd->nr_balance_failed = 0;
 
 	/* We were unbalanced, so reset the balancing interval */
 	sd->balance_interval = sd->min_interval;
 
 	return nr_moved;
 
 out_balanced:
 	spin_unlock(&this_rq->lock);
 
 	/* tune up the balancing interval */
 	if (sd->balance_interval < sd->max_interval)
 		sd->balance_interval *= 2;
 
 	return 0;
 }
 
 /*
  * Check this_cpu to ensure it is balanced within domain. Attempt to move
  * tasks if there is an imbalance.
  *
  * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
  * this_rq is locked.
  */
 static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
 				struct sched_domain *sd)
 {
 	struct sched_group *group;
 	runqueue_t *busiest = NULL;
 	unsigned long imbalance;
 	int nr_moved = 0;
 
 	schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
 	group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
 	if (!group) {
 		schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
 		goto out;
 	}
 
 	busiest = find_busiest_queue(group);
 	if (!busiest || busiest == this_rq) {
 		schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
 		goto out;
 	}
 
 	/* Attempt to move tasks */
 	double_lock_balance(this_rq, busiest);
 
 	schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
 	nr_moved = move_tasks(this_rq, this_cpu, busiest,
 					imbalance, sd, NEWLY_IDLE);
 	if (!nr_moved)
 		schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
 
 	spin_unlock(&busiest->lock);
 
 out:
 	return nr_moved;
 }
 
 /*
  * idle_balance is called by schedule() if this_cpu is about to become
  * idle. Attempts to pull tasks from other CPUs.
  */
 static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
 {
 	struct sched_domain *sd;
 
 	for_each_domain(this_cpu, sd) {
 		if (sd->flags & SD_BALANCE_NEWIDLE) {
 			if (load_balance_newidle(this_cpu, this_rq, sd)) {
 				/* We've pulled tasks over so stop searching */
 				break;
 			}
 		}
 	}
 }
 
 /*
  * active_load_balance is run by migration threads. It pushes a running
  * task off the cpu. It can be required to correctly have at least 1 task
  * running on each physical CPU where possible, and not have a physical /
  * logical imbalance.
  *
  * Called with busiest locked.
  */
 static void active_load_balance(runqueue_t *busiest, int busiest_cpu)
 {
 	struct sched_domain *sd;
 	struct sched_group *group, *busy_group;
 	int i;
 
 	schedstat_inc(busiest, alb_cnt);
 	if (busiest->nr_running <= 1)
 		return;
 
 	for_each_domain(busiest_cpu, sd)
 		if (cpu_isset(busiest->push_cpu, sd->span))
 			break;
 	if (!sd)
 		return;
 
 	group = sd->groups;
 	while (!cpu_isset(busiest_cpu, group->cpumask))
 		group = group->next;
 	busy_group = group;
 
 	group = sd->groups;
 	do {
 		cpumask_t tmp;
 		runqueue_t *rq;
 		int push_cpu = 0;
 
 		if (group == busy_group)
 			goto next_group;
 
 		cpus_and(tmp, group->cpumask, cpu_online_map);
 		if (!cpus_weight(tmp))
 			goto next_group;
 
 		for_each_cpu_mask(i, tmp) {
 			if (!idle_cpu(i))
 				goto next_group;
 			push_cpu = i;
 		}
 
 		rq = cpu_rq(push_cpu);
 
 		/*
 		 * This condition is "impossible", but since load
 		 * balancing is inherently a bit racy and statistical,
 		 * it can trigger.. Reported by Bjorn Helgaas on a
 		 * 128-cpu setup.
 		 */
 		if (unlikely(busiest == rq))
 			goto next_group;
 		double_lock_balance(busiest, rq);
 		if (move_tasks(rq, push_cpu, busiest, 1, sd, IDLE)) {
 			schedstat_inc(busiest, alb_lost);
 			schedstat_inc(rq, alb_gained);
 		} else {
 			schedstat_inc(busiest, alb_failed);
 		}
 		spin_unlock(&rq->lock);
 next_group:
 		group = group->next;
 	} while (group != sd->groups);
 }
 
 /*
  * rebalance_tick will get called every timer tick, on every CPU.
  *
  * It checks each scheduling domain to see if it is due to be balanced,
  * and initiates a balancing operation if so.
  *
  * Balancing parameters are set up in arch_init_sched_domains.
  */
 
 /* Don't have all balancing operations going off at once */
 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
 
 static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
 			   enum idle_type idle)
 {
 	unsigned long old_load, this_load;
 	unsigned long j = jiffies + CPU_OFFSET(this_cpu);
 	struct sched_domain *sd;
 
 	/* Update our load */
 	old_load = this_rq->cpu_load;
 	this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
 	/*
 	 * Round up the averaging division if load is increasing. This
 	 * prevents us from getting stuck on 9 if the load is 10, for
 	 * example.
 	 */
 	if (this_load > old_load)
 		old_load++;
 	this_rq->cpu_load = (old_load + this_load) / 2;
 
 	for_each_domain(this_cpu, sd) {
 		unsigned long interval = sd->balance_interval;
 
 		if (idle != IDLE)
 			interval *= sd->busy_factor;
 
 		/* scale ms to jiffies */
 		interval = msecs_to_jiffies(interval);
 		if (unlikely(!interval))
 			interval = 1;
 
 		if (j - sd->last_balance >= interval) {
 			if (load_balance(this_cpu, this_rq, sd, idle)) {
 				/* We've pulled tasks over so no longer idle */
 				idle = NOT_IDLE;
 			}
 			sd->last_balance += interval;
 		}
 	}
 }
 #else
 /*
  * on UP we do not need to balance between CPUs:
  */
 static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle)
 {
 }
 static inline void idle_balance(int cpu, runqueue_t *rq)
 {
 }
 #endif
 
 static inline int wake_priority_sleeper(runqueue_t *rq)
 {
 	int ret = 0;
 #ifdef CONFIG_SCHED_SMT
 	spin_lock(&rq->lock);
 	/*
 	 * If an SMT sibling task has been put to sleep for priority
 	 * reasons reschedule the idle task to see if it can now run.
 	 */
 	if (rq->nr_running) {
 		resched_task(rq->idle);
 		ret = 1;
 	}
 	spin_unlock(&rq->lock);
 #endif
 	return ret;
 }
 
 DEFINE_PER_CPU(struct kernel_stat, kstat);
 
 EXPORT_PER_CPU_SYMBOL(kstat);
 
 /*
  * We place interactive tasks back into the active array, if possible.
  *
  * To guarantee that this does not starve expired tasks we ignore the
  * interactivity of a task if the first expired task had to wait more
  * than a 'reasonable' amount of time. This deadline timeout is
  * load-dependent, as the frequency of array switched decreases with
  * increasing number of running tasks. We also ignore the interactivity
  * if a better static_prio task has expired:
  */
 #define EXPIRED_STARVING(rq) \
 	((STARVATION_LIMIT && ((rq)->expired_timestamp && \
 		(jiffies - (rq)->expired_timestamp >= \
 			STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
 			((rq)->curr->static_prio > (rq)->best_expired_prio))
 
 /*
  * This function gets called by the timer code, with HZ frequency.
  * We call it with interrupts disabled.
  *
  * It also gets called by the fork code, when changing the parent's
  * timeslices.
  */
 void scheduler_tick(int user_ticks, int sys_ticks)
 {
 	int cpu = smp_processor_id();
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 	runqueue_t *rq = this_rq();
 	task_t *p = current;
 
 	rq->timestamp_last_tick = sched_clock();
 
 	if (rcu_pending(cpu))
 		rcu_check_callbacks(cpu, user_ticks);
 
 	/* note: this timer irq context must be accounted for as well */
 	if (hardirq_count() - HARDIRQ_OFFSET) {
 		cpustat->irq += sys_ticks;
 		sys_ticks = 0;
 	} else if (softirq_count()) {
 		cpustat->softirq += sys_ticks;
 		sys_ticks = 0;
 	}
 
 	if (p == rq->idle) {
 		if (atomic_read(&rq->nr_iowait) > 0)
 			cpustat->iowait += sys_ticks;
 		else
 			cpustat->idle += sys_ticks;
 		if (wake_priority_sleeper(rq))
 			goto out;
 		rebalance_tick(cpu, rq, IDLE);
 		return;
 	}
 	if (TASK_NICE(p) > 0)
 		cpustat->nice += user_ticks;
 	else
 		cpustat->user += user_ticks;
 	cpustat->system += sys_ticks;
 
 	/* Task might have expired already, but not scheduled off yet */
 	if (p->array != rq->active) {
 		set_tsk_need_resched(p);
 		goto out;
 	}
 	spin_lock(&rq->lock);
 	/*
 	 * The task was running during this tick - update the
 	 * time slice counter. Note: we do not update a thread's
 	 * priority until it either goes to sleep or uses up its
 	 * timeslice. This makes it possible for interactive tasks
 	 * to use up their timeslices at their highest priority levels.
 	 */
 	if (rt_task(p)) {
 		/*
 		 * RR tasks need a special form of timeslice management.
 		 * FIFO tasks have no timeslices.
 		 */
 		if ((p->policy == SCHED_RR) && !--p->time_slice) {
 			p->time_slice = task_timeslice(p);
 			p->first_time_slice = 0;
 			set_tsk_need_resched(p);
 
 			/* put it at the end of the queue: */
 			dequeue_task(p, rq->active);
 			enqueue_task(p, rq->active);
 		}
 		goto out_unlock;
 	}
 	if (!--p->time_slice) {
 		dequeue_task(p, rq->active);
 		set_tsk_need_resched(p);
 		p->prio = effective_prio(p);
 		p->time_slice = task_timeslice(p);
 		p->first_time_slice = 0;
 
 		if (!rq->expired_timestamp)
 			rq->expired_timestamp = jiffies;
 		if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) {
 			enqueue_task(p, rq->expired);
 			if (p->static_prio < rq->best_expired_prio)
 				rq->best_expired_prio = p->static_prio;
 		} else
 			enqueue_task(p, rq->active);
 	} else {
 		/*
 		 * Prevent a too long timeslice allowing a task to monopolize
 		 * the CPU. We do this by splitting up the timeslice into
 		 * smaller pieces.
 		 *
 		 * Note: this does not mean the task's timeslices expire or
 		 * get lost in any way, they just might be preempted by
 		 * another task of equal priority. (one with higher
 		 * priority would have preempted this task already.) We
 		 * requeue this task to the end of the list on this priority
 		 * level, which is in essence a round-robin of tasks with
 		 * equal priority.
 		 *
 		 * This only applies to tasks in the interactive
 		 * delta range with at least TIMESLICE_GRANULARITY to requeue.
 		 */
 		if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
 			p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
 			(p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
 			(p->array == rq->active)) {
 
 			dequeue_task(p, rq->active);
 			set_tsk_need_resched(p);
 			p->prio = effective_prio(p);
 			enqueue_task(p, rq->active);
 		}
 	}
 out_unlock:
 	spin_unlock(&rq->lock);
 out:
 	rebalance_tick(cpu, rq, NOT_IDLE);
 }
 
 #ifdef CONFIG_SCHED_SMT
 static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
 {
 	struct sched_domain *sd = this_rq->sd;
 	cpumask_t sibling_map;
 	int i;
 
 	if (!(sd->flags & SD_SHARE_CPUPOWER))
 		return;
 
 	/*
 	 * Unlock the current runqueue because we have to lock in
 	 * CPU order to avoid deadlocks. Caller knows that we might
 	 * unlock. We keep IRQs disabled.
 	 */
 	spin_unlock(&this_rq->lock);
 
 	cpus_and(sibling_map, sd->span, cpu_online_map);
 
 	for_each_cpu_mask(i, sibling_map)
 		spin_lock(&cpu_rq(i)->lock);
 	/*
 	 * We clear this CPU from the mask. This both simplifies the
 	 * inner loop and keps this_rq locked when we exit:
 	 */
 	cpu_clear(this_cpu, sibling_map);
 
 	for_each_cpu_mask(i, sibling_map) {
 		runqueue_t *smt_rq = cpu_rq(i);
 
 		/*
 		 * If an SMT sibling task is sleeping due to priority
 		 * reasons wake it up now.
 		 */
 		if (smt_rq->curr == smt_rq->idle && smt_rq->nr_running)
 			resched_task(smt_rq->idle);
 	}
 
 	for_each_cpu_mask(i, sibling_map)
 		spin_unlock(&cpu_rq(i)->lock);
 	/*
 	 * We exit with this_cpu's rq still held and IRQs
 	 * still disabled:
 	 */
 }
 
 static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
 {
 	struct sched_domain *sd = this_rq->sd;
 	cpumask_t sibling_map;
 	prio_array_t *array;
 	int ret = 0, i;
 	task_t *p;
 
 	if (!(sd->flags & SD_SHARE_CPUPOWER))
 		return 0;
 
 	/*
 	 * The same locking rules and details apply as for
 	 * wake_sleeping_dependent():
 	 */
 	spin_unlock(&this_rq->lock);
 	cpus_and(sibling_map, sd->span, cpu_online_map);
 	for_each_cpu_mask(i, sibling_map)
 		spin_lock(&cpu_rq(i)->lock);
 	cpu_clear(this_cpu, sibling_map);
 
 	/*
 	 * Establish next task to be run - it might have gone away because
 	 * we released the runqueue lock above:
 	 */
 	if (!this_rq->nr_running)
 		goto out_unlock;
 	array = this_rq->active;
 	if (!array->nr_active)
 		array = this_rq->expired;
 	BUG_ON(!array->nr_active);
 
 	p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next,
 		task_t, run_list);
 
 	for_each_cpu_mask(i, sibling_map) {
 		runqueue_t *smt_rq = cpu_rq(i);
 		task_t *smt_curr = smt_rq->curr;
 
 		/*
 		 * If a user task with lower static priority than the
 		 * running task on the SMT sibling is trying to schedule,
 		 * delay it till there is proportionately less timeslice
 		 * left of the sibling task to prevent a lower priority
 		 * task from using an unfair proportion of the
 		 * physical cpu's resources. -ck
 		 */
 		if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) >
 			task_timeslice(p) || rt_task(smt_curr)) &&
 			p->mm && smt_curr->mm && !rt_task(p))
 				ret = 1;
 
 		/*
 		 * Reschedule a lower priority task on the SMT sibling,
 		 * or wake it up if it has been put to sleep for priority
 		 * reasons.
 		 */
 		if ((((p->time_slice * (100 - sd->per_cpu_gain) / 100) >
 			task_timeslice(smt_curr) || rt_task(p)) &&
 			smt_curr->mm && p->mm && !rt_task(smt_curr)) ||
 			(smt_curr == smt_rq->idle && smt_rq->nr_running))
 				resched_task(smt_curr);
 	}
 out_unlock:
 	for_each_cpu_mask(i, sibling_map)
 		spin_unlock(&cpu_rq(i)->lock);
 	return ret;
 }
 #else
 static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
 {
 }
 
 static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
 {
 	return 0;
 }
 #endif
 
 /*
  * schedule() is the main scheduler function.
  */
 asmlinkage void __sched schedule(void)
 {
 	long *switch_count;
 	task_t *prev, *next;
 	runqueue_t *rq;
 	prio_array_t *array;
 	struct list_head *queue;
 	unsigned long long now;
 	unsigned long run_time;
 	int cpu, idx;
 
 	/*
 	 * Test if we are atomic.  Since do_exit() needs to call into
 	 * schedule() atomically, we ignore that path for now.
 	 * Otherwise, whine if we are scheduling when we should not be.
 	 */
 	if (likely(!(current->state & (TASK_DEAD | TASK_ZOMBIE)))) {
 		if (unlikely(in_atomic())) {
 			printk(KERN_ERR "bad: scheduling while atomic!\n");
 			dump_stack();
 		}
 	}
 
 need_resched:
 	preempt_disable();
 	prev = current;
 	rq = this_rq();
 
 	/*
 	 * The idle thread is not allowed to schedule!
 	 * Remove this check after it has been exercised a bit.
 	 */
 	if (unlikely(current == rq->idle) && current->state != TASK_RUNNING) {
 		printk(KERN_ERR "bad: scheduling from the idle thread!\n");
 		dump_stack();
 	}
 
 	release_kernel_lock(prev);
 	schedstat_inc(rq, sched_cnt);
 	now = sched_clock();
 	if (likely(now - prev->timestamp < NS_MAX_SLEEP_AVG))
 		run_time = now - prev->timestamp;
 	else
 		run_time = NS_MAX_SLEEP_AVG;
 
 	/*
 	 * Tasks with interactive credits get charged less run_time
 	 * at high sleep_avg to delay them losing their interactive
 	 * status
 	 */
 	if (HIGH_CREDIT(prev))
 		run_time /= (CURRENT_BONUS(prev) ? : 1);
 
 	spin_lock_irq(&rq->lock);
 
 	/*
 	 * if entering off of a kernel preemption go straight
 	 * to picking the next task.
 	 */
 	switch_count = &prev->nivcsw;
 	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
 		switch_count = &prev->nvcsw;
 		if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
 				unlikely(signal_pending(prev))))
 			prev->state = TASK_RUNNING;
 		else
 			deactivate_task(prev, rq);
 	}
 
 	cpu = smp_processor_id();
 	if (unlikely(!rq->nr_running)) {
 go_idle:
 		idle_balance(cpu, rq);
 		if (!rq->nr_running) {
 			next = rq->idle;
 			rq->expired_timestamp = 0;
 			wake_sleeping_dependent(cpu, rq);
 			/*
 			 * wake_sleeping_dependent() might have released
 			 * the runqueue, so break out if we got new
 			 * tasks meanwhile:
 			 */
 			if (!rq->nr_running)
 				goto switch_tasks;
 		}
 	} else {
 		if (dependent_sleeper(cpu, rq)) {
 			schedstat_inc(rq, sched_goidle);
 			next = rq->idle;
 			goto switch_tasks;
 		}
 		/*
 		 * dependent_sleeper() releases and reacquires the runqueue
 		 * lock, hence go into the idle loop if the rq went
 		 * empty meanwhile:
 		 */
 		if (unlikely(!rq->nr_running))
 			goto go_idle;
 	}
 
 	array = rq->active;
 	if (unlikely(!array->nr_active)) {
 		/*
 		 * Switch the active and expired arrays.
 		 */
 		schedstat_inc(rq, sched_switch);
 		rq->active = rq->expired;
 		rq->expired = array;
 		array = rq->active;
 		rq->expired_timestamp = 0;
 		rq->best_expired_prio = MAX_PRIO;
 	} else
 		schedstat_inc(rq, sched_noswitch);
 
 	idx = sched_find_first_bit(array->bitmap);
 	queue = array->queue + idx;
 	next = list_entry(queue->next, task_t, run_list);
 
 	if (!rt_task(next) && next->activated > 0) {
 		unsigned long long delta = now - next->timestamp;
 
 		if (next->activated == 1)
 			delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
 
 		array = next->array;
 		dequeue_task(next, array);
 		recalc_task_prio(next, next->timestamp + delta);
 		enqueue_task(next, array);
 	}
 	next->activated = 0;
 switch_tasks:
 	prefetch(next);
 	clear_tsk_need_resched(prev);
 	rcu_qsctr_inc(task_cpu(prev));
 
 	prev->sleep_avg -= run_time;
 	if ((long)prev->sleep_avg <= 0) {
 		prev->sleep_avg = 0;
 		if (!(HIGH_CREDIT(prev) || LOW_CREDIT(prev)))
 			prev->interactive_credit--;
 	}
 	prev->timestamp = prev->last_ran = now;
 
 	sched_info_switch(prev, next);
 	if (likely(prev != next)) {
 		next->timestamp = now;
 		rq->nr_switches++;
 		rq->curr = next;
 		++*switch_count;
 
 		prepare_arch_switch(rq, next);
 		prev = context_switch(rq, prev, next);
 		barrier();
 
 		finish_task_switch(prev);
 	} else
 		spin_unlock_irq(&rq->lock);
 
 	reacquire_kernel_lock(current);
 	preempt_enable_no_resched();
 	if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
 		goto need_resched;
 }
 
 EXPORT_SYMBOL(schedule);
 
 #ifdef CONFIG_PREEMPT
 /*
  * this is is the entry point to schedule() from in-kernel preemption
  * off of preempt_enable.  Kernel preemptions off return from interrupt
  * occur there and call schedule directly.
  */
 asmlinkage void __sched preempt_schedule(void)
 {
 	struct thread_info *ti = current_thread_info();
 
 	/*
 	 * If there is a non-zero preempt_count or interrupts are disabled,
 	 * we do not want to preempt the current task.  Just return..
 	 */
 	if (unlikely(ti->preempt_count || irqs_disabled()))
 		return;
 
 need_resched:
 	ti->preempt_count = PREEMPT_ACTIVE;
 	schedule();
 	ti->preempt_count = 0;
 
 	/* we could miss a preemption opportunity between schedule and now */
 	barrier();
 	if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
 		goto need_resched;
 }
 
 EXPORT_SYMBOL(preempt_schedule);
 #endif /* CONFIG_PREEMPT */
 
 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key)
 {
 	task_t *p = curr->task;
 	return try_to_wake_up(p, mode, sync);
 }
 
 EXPORT_SYMBOL(default_wake_function);
 
 /*
  * The core wakeup function.  Non-exclusive wakeups (nr_exclusive == 0) just
  * wake everything up.  If it's an exclusive wakeup (nr_exclusive == small +ve
  * number) then we wake all the non-exclusive tasks and one exclusive task.
  *
  * There are circumstances in which we can try to wake a task which has already
  * started to run but is not in state TASK_RUNNING.  try_to_wake_up() returns
  * zero in this (rare) case, and we handle it by continuing to scan the queue.
  */
 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
 			     int nr_exclusive, int sync, void *key)
 {
 	struct list_head *tmp, *next;
 
 	list_for_each_safe(tmp, next, &q->task_list) {
 		wait_queue_t *curr;
 		unsigned flags;
 		curr = list_entry(tmp, wait_queue_t, task_list);
 		flags = curr->flags;
 		if (curr->func(curr, mode, sync, key) &&
 		    (flags & WQ_FLAG_EXCLUSIVE) &&
 		    !--nr_exclusive)
 			break;
 	}
 }
 
 /**
  * __wake_up - wake up threads blocked on a waitqueue.
  * @q: the waitqueue
  * @mode: which threads
  * @nr_exclusive: how many wake-one or wake-many threads to wake up
  */
 void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
 				int nr_exclusive, void *key)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&q->lock, flags);
 	__wake_up_common(q, mode, nr_exclusive, 0, key);
 	spin_unlock_irqrestore(&q->lock, flags);
 }
 
 EXPORT_SYMBOL(__wake_up);
 
 /*
  * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
  */
 void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
 {
 	__wake_up_common(q, mode, 1, 0, NULL);
 }
 
 /**
  * __wake_up - sync- wake up threads blocked on a waitqueue.
  * @q: the waitqueue
  * @mode: which threads
  * @nr_exclusive: how many wake-one or wake-many threads to wake up
  *
  * The sync wakeup differs that the waker knows that it will schedule
  * away soon, so while the target thread will be woken up, it will not
  * be migrated to another CPU - ie. the two threads are 'synchronized'
  * with each other. This can prevent needless bouncing between CPUs.
  *
  * On UP it can prevent extra preemption.
  */
 void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
 {
 	unsigned long flags;
 	int sync = 1;
 
 	if (unlikely(!q))
 		return;
 
 	if (unlikely(!nr_exclusive))
 		sync = 0;
 
 	spin_lock_irqsave(&q->lock, flags);
 	__wake_up_common(q, mode, nr_exclusive, sync, NULL);
 	spin_unlock_irqrestore(&q->lock, flags);
 }
 EXPORT_SYMBOL_GPL(__wake_up_sync);	/* For internal use only */
 
 void fastcall complete(struct completion *x)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&x->wait.lock, flags);
 	x->done++;
 	__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
 			 1, 0, NULL);
 	spin_unlock_irqrestore(&x->wait.lock, flags);
 }
 EXPORT_SYMBOL(complete);
 
 void fastcall complete_all(struct completion *x)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&x->wait.lock, flags);
 	x->done += UINT_MAX/2;
 	__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
 			 0, 0, NULL);
 	spin_unlock_irqrestore(&x->wait.lock, flags);
 }
 EXPORT_SYMBOL(complete_all);
 
 void fastcall __sched wait_for_completion(struct completion *x)
 {
 	might_sleep();
 	spin_lock_irq(&x->wait.lock);
 	if (!x->done) {
 		DECLARE_WAITQUEUE(wait, current);
 
 		wait.flags |= WQ_FLAG_EXCLUSIVE;
 		__add_wait_queue_tail(&x->wait, &wait);
 		do {
 			__set_current_state(TASK_UNINTERRUPTIBLE);
 			spin_unlock_irq(&x->wait.lock);
 			schedule();
 			spin_lock_irq(&x->wait.lock);
 		} while (!x->done);
 		__remove_wait_queue(&x->wait, &wait);
 	}
 	x->done--;
 	spin_unlock_irq(&x->wait.lock);
 }
 EXPORT_SYMBOL(wait_for_completion);
 
 #define	SLEEP_ON_VAR					\
 	unsigned long flags;				\
 	wait_queue_t wait;				\
 	init_waitqueue_entry(&wait, current);
 
 #define SLEEP_ON_HEAD					\
 	spin_lock_irqsave(&q->lock,flags);		\
 	__add_wait_queue(q, &wait);			\
 	spin_unlock(&q->lock);
 
 #define	SLEEP_ON_TAIL					\
 	spin_lock_irq(&q->lock);			\
 	__remove_wait_queue(q, &wait);			\
 	spin_unlock_irqrestore(&q->lock, flags);
 
 void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
 {
 	SLEEP_ON_VAR
 
 	current->state = TASK_INTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
 	schedule();
 	SLEEP_ON_TAIL
 }
 
 EXPORT_SYMBOL(interruptible_sleep_on);
 
 long fastcall __sched interruptible_sleep_on_timeout(wait_queue_head_t *q, 
 						long timeout)
 {
 	SLEEP_ON_VAR
 
 	current->state = TASK_INTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
 	timeout = schedule_timeout(timeout);
 	SLEEP_ON_TAIL
 
 	return timeout;
 }
 
 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
 
 void fastcall __sched sleep_on(wait_queue_head_t *q)
 {
 	SLEEP_ON_VAR
 
 	current->state = TASK_UNINTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
 	schedule();
 	SLEEP_ON_TAIL
 }
 
 EXPORT_SYMBOL(sleep_on);
 
 long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
 {
 	SLEEP_ON_VAR
 
 	current->state = TASK_UNINTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
 	timeout = schedule_timeout(timeout);
 	SLEEP_ON_TAIL
 
 	return timeout;
 }
 
 EXPORT_SYMBOL(sleep_on_timeout);
 
 void set_user_nice(task_t *p, long nice)
 {
 	unsigned long flags;
 	prio_array_t *array;
 	runqueue_t *rq;
 	int old_prio, new_prio, delta;
 
 	if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
 		return;
 	/*
 	 * We have to be careful, if called from sys_setpriority(),
 	 * the task might be in the middle of scheduling on another CPU.
 	 */
 	rq = task_rq_lock(p, &flags);
 	/*
 	 * The RT priorities are set via setscheduler(), but we still
 	 * allow the 'normal' nice value to be set - but as expected
 	 * it wont have any effect on scheduling until the task is
 	 * not SCHED_NORMAL:
 	 */
 	if (rt_task(p)) {
 		p->static_prio = NICE_TO_PRIO(nice);
 		goto out_unlock;
 	}
 	array = p->array;
 	if (array)
 		dequeue_task(p, array);
 
 	old_prio = p->prio;
 	new_prio = NICE_TO_PRIO(nice);
 	delta = new_prio - old_prio;
 	p->static_prio = NICE_TO_PRIO(nice);
 	p->prio += delta;
 
 	if (array) {
 		enqueue_task(p, array);
 		/*
 		 * If the task increased its priority or is running and
 		 * lowered its priority, then reschedule its CPU:
 		 */
 		if (delta < 0 || (delta > 0 && task_running(rq, p)))
 			resched_task(rq->curr);
 	}
 out_unlock:
 	task_rq_unlock(rq, &flags);
 }
 
 EXPORT_SYMBOL(set_user_nice);
 
 #ifdef __ARCH_WANT_SYS_NICE
 
 /*
  * sys_nice - change the priority of the current process.
  * @increment: priority increment
  *
  * sys_setpriority is a more generic, but much slower function that
  * does similar things.
  */
 asmlinkage long sys_nice(int increment)
 {
 	int retval;
 	long nice;
 
 	/*
 	 * Setpriority might change our priority at the same moment.
 	 * We don't have to worry. Conceptually one call occurs first
 	 * and we have a single winner.
 	 */
 	if (increment < 0) {
 		if (!capable(CAP_SYS_NICE))
 			return -EPERM;
 		if (increment < -40)
 			increment = -40;
 	}
 	if (increment > 40)
 		increment = 40;
 
 	nice = PRIO_TO_NICE(current->static_prio) + increment;
 	if (nice < -20)
 		nice = -20;
 	if (nice > 19)
 		nice = 19;
 
 	retval = security_task_setnice(current, nice);
 	if (retval)
 		return retval;
 
 	set_user_nice(current, nice);
 	return 0;
 }
 
 #endif
 
 /**
  * task_prio - return the priority value of a given task.
  * @p: the task in question.
  *
  * This is the priority value as seen by users in /proc.
  * RT tasks are offset by -200. Normal tasks are centered
  * around 0, value goes from -16 to +15.
  */
 int task_prio(const task_t *p)
 {
 	return p->prio - MAX_RT_PRIO;
 }
 
 /**
  * task_nice - return the nice value of a given task.
  * @p: the task in question.
  */
 int task_nice(const task_t *p)
 {
 	return TASK_NICE(p);
 }
 
 EXPORT_SYMBOL(task_nice);
 
 /**
  * idle_cpu - is a given cpu idle currently?
  * @cpu: the processor in question.
  */
 int idle_cpu(int cpu)
 {
 	return cpu_curr(cpu) == cpu_rq(cpu)->idle;
 }
 
 EXPORT_SYMBOL_GPL(idle_cpu);
 
 /**
  * find_process_by_pid - find a process with a matching PID value.
  * @pid: the pid in question.
  */
 static inline task_t *find_process_by_pid(pid_t pid)
 {
 	return pid ? find_task_by_pid(pid) : current;
 }
 
 /* Actually do priority change: must hold rq lock. */
 static void __setscheduler(struct task_struct *p, int policy, int prio)
 {
 	BUG_ON(p->array);
 	p->policy = policy;
 	p->rt_priority = prio;
 	if (policy != SCHED_NORMAL)
 		p->prio = MAX_USER_RT_PRIO-1 - p->rt_priority;
 	else
 		p->prio = p->static_prio;
 }
 
 /*
  * setscheduler - change the scheduling policy and/or RT priority of a thread.
  */
 static int setscheduler(pid_t pid, int policy, struct sched_param __user *param)
 {
 	struct sched_param lp;
 	int retval = -EINVAL;
 	int oldprio;
 	prio_array_t *array;
 	unsigned long flags;
 	runqueue_t *rq;
 	task_t *p;
 
 	if (!param || pid < 0)
 		goto out_nounlock;
 
 	retval = -EFAULT;
 	if (copy_from_user(&lp, param, sizeof(struct sched_param)))
 		goto out_nounlock;
 
 	/*
 	 * We play safe to avoid deadlocks.
 	 */
 	read_lock_irq(&tasklist_lock);
 
 	p = find_process_by_pid(pid);
 
 	retval = -ESRCH;
 	if (!p)
 		goto out_unlock_tasklist;
 
 	/*
 	 * To be able to change p->policy safely, the apropriate
 	 * runqueue lock must be held.
 	 */
 	rq = task_rq_lock(p, &flags);
 
 	if (policy < 0)
 		policy = p->policy;
 	else {
 		retval = -EINVAL;
 		if (policy != SCHED_FIFO && policy != SCHED_RR &&
 				policy != SCHED_NORMAL)
 			goto out_unlock;
 	}
 	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
 
 	/*
 	 * Valid priorities for SCHED_FIFO and SCHED_RR are
 	 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
 	 */
 	retval = -EINVAL;
 	if (lp.sched_priority < 0 || lp.sched_priority > MAX_USER_RT_PRIO-1)
 		goto out_unlock;
 	if ((policy == SCHED_NORMAL) != (lp.sched_priority == 0))
 		goto out_unlock;
 
 	retval = -EPERM;
 	if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
 	    !capable(CAP_SYS_NICE))
 		goto out_unlock;
 	if ((current->euid != p->euid) && (current->euid != p->uid) &&
 	    !capable(CAP_SYS_NICE))
 		goto out_unlock;
 
 	retval = security_task_setscheduler(p, policy, &lp);
 	if (retval)
 		goto out_unlock;
 
 	array = p->array;
 	if (array)
 		deactivate_task(p, task_rq(p));
 	retval = 0;
 	oldprio = p->prio;
 	__setscheduler(p, policy, lp.sched_priority);
 	if (array) {
 		__activate_task(p, task_rq(p));
 		/*
 		 * Reschedule if we are currently running on this runqueue and
 		 * our priority decreased, or if we are not currently running on
 		 * this runqueue and our priority is higher than the current's
 		 */
 		if (task_running(rq, p)) {
 			if (p->prio > oldprio)
 				resched_task(rq->curr);
 		} else if (TASK_PREEMPTS_CURR(p, rq))
 			resched_task(rq->curr);
 	}
 
 out_unlock:
 	task_rq_unlock(rq, &flags);
 out_unlock_tasklist:
 	read_unlock_irq(&tasklist_lock);
 
 out_nounlock:
 	return retval;
 }
 
 /**
  * sys_sched_setscheduler - set/change the scheduler policy and RT priority
  * @pid: the pid in question.
  * @policy: new policy
  * @param: structure containing the new RT priority.
  */
 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
 				       struct sched_param __user *param)
 {
 	return setscheduler(pid, policy, param);
 }
 
 /**
  * sys_sched_setparam - set/change the RT priority of a thread
  * @pid: the pid in question.
  * @param: structure containing the new RT priority.
  */
 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
 {
 	return setscheduler(pid, -1, param);
 }
 
 /**
  * sys_sched_getscheduler - get the policy (scheduling class) of a thread
  * @pid: the pid in question.
  */
 asmlinkage long sys_sched_getscheduler(pid_t pid)
 {
 	int retval = -EINVAL;
 	task_t *p;
 
 	if (pid < 0)
 		goto out_nounlock;
 
 	retval = -ESRCH;
 	read_lock(&tasklist_lock);
 	p = find_process_by_pid(pid);
 	if (p) {
 		retval = security_task_getscheduler(p);
 		if (!retval)
 			retval = p->policy;
 	}
 	read_unlock(&tasklist_lock);
 
 out_nounlock:
 	return retval;
 }
 
 /**
  * sys_sched_getscheduler - get the RT priority of a thread
  * @pid: the pid in question.
  * @param: structure containing the RT priority.
  */
 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
 {
 	struct sched_param lp;
 	int retval = -EINVAL;
 	task_t *p;
 
 	if (!param || pid < 0)
 		goto out_nounlock;
 
 	read_lock(&tasklist_lock);
 	p = find_process_by_pid(pid);
 	retval = -ESRCH;
 	if (!p)
 		goto out_unlock;
 
 	retval = security_task_getscheduler(p);
 	if (retval)
 		goto out_unlock;
 
 	lp.sched_priority = p->rt_priority;
 	read_unlock(&tasklist_lock);
 
 	/*
 	 * This one might sleep, we cannot do it with a spinlock held ...
 	 */
 	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
 
 out_nounlock:
 	return retval;
 
 out_unlock:
 	read_unlock(&tasklist_lock);
 	return retval;
 }
 
 long sched_setaffinity(pid_t pid, cpumask_t new_mask)
 {
 	task_t *p;
 	int retval;
 
 	lock_cpu_hotplug();
 	read_lock(&tasklist_lock);
 
 	p = find_process_by_pid(pid);
 	if (!p) {
 		read_unlock(&tasklist_lock);
 		unlock_cpu_hotplug();
 		return -ESRCH;
 	}
 
 	/*
 	 * It is not safe to call set_cpus_allowed with the
 	 * tasklist_lock held.  We will bump the task_struct's
 	 * usage count and then drop tasklist_lock.
 	 */
 	get_task_struct(p);
 	read_unlock(&tasklist_lock);
 
 	retval = -EPERM;
 	if ((current->euid != p->euid) && (current->euid != p->uid) &&
 			!capable(CAP_SYS_NICE))
 		goto out_unlock;
 
 	retval = set_cpus_allowed(p, new_mask);
 
 out_unlock:
 	put_task_struct(p);
 	unlock_cpu_hotplug();
 	return retval;
 }
 
 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
 			     cpumask_t *new_mask)
 {
 	if (len < sizeof(cpumask_t)) {
 		memset(new_mask, 0, sizeof(cpumask_t));
 	} else if (len > sizeof(cpumask_t)) {
 		len = sizeof(cpumask_t);
 	}
 	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
 }
 
 /**
  * sys_sched_setaffinity - set the cpu affinity of a process
  * @pid: pid of the process
  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
  * @user_mask_ptr: user-space pointer to the new cpu mask
  */
 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
 				      unsigned long __user *user_mask_ptr)
 {
 	cpumask_t new_mask;
 	int retval;
 
 	retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
 	if (retval)
 		return retval;
 
 	return sched_setaffinity(pid, new_mask);
 }
 
 /*
  * Represents all cpu's present in the system
  * In systems capable of hotplug, this map could dynamically grow
  * as new cpu's are detected in the system via any platform specific
  * method, such as ACPI for e.g.
  */
 
 cpumask_t cpu_present_map;
 EXPORT_SYMBOL(cpu_present_map);
 
 #ifndef CONFIG_SMP
 cpumask_t cpu_online_map = CPU_MASK_ALL;
 cpumask_t cpu_possible_map = CPU_MASK_ALL;
 #endif
 
 long sched_getaffinity(pid_t pid, cpumask_t *mask)
 {
 	int retval;
 	task_t *p;
 
 	lock_cpu_hotplug();
 	read_lock(&tasklist_lock);
 
 	retval = -ESRCH;
 	p = find_process_by_pid(pid);
 	if (!p)
 		goto out_unlock;
 
 	retval = 0;
 	cpus_and(*mask, p->cpus_allowed, cpu_possible_map);
 
 out_unlock:
 	read_unlock(&tasklist_lock);
 	unlock_cpu_hotplug();
 	if (retval)
 		return retval;
 
 	return 0;
 }
 
 /**
  * sys_sched_getaffinity - get the cpu affinity of a process
  * @pid: pid of the process
  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
  * @user_mask_ptr: user-space pointer to hold the current cpu mask
  */
 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
 				      unsigned long __user *user_mask_ptr)
 {
 	int ret;
 	cpumask_t mask;
 
 	if (len < sizeof(cpumask_t))
 		return -EINVAL;
 
 	ret = sched_getaffinity(pid, &mask);
 	if (ret < 0)
 		return ret;
 
 	if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
 		return -EFAULT;
 
 	return sizeof(cpumask_t);
 }
 
 /**
  * sys_sched_yield - yield the current processor to other threads.
  *
  * this function yields the current CPU by moving the calling thread
  * to the expired array. If there are no other threads running on this
  * CPU then this function will return.
  */
 asmlinkage long sys_sched_yield(void)
 {
 	runqueue_t *rq = this_rq_lock();
 	prio_array_t *array = current->array;
 	prio_array_t *target = rq->expired;
 
 	schedstat_inc(rq, yld_cnt);
 	/*
 	 * We implement yielding by moving the task into the expired
 	 * queue.
 	 *
 	 * (special rule: RT tasks will just roundrobin in the active
 	 *  array.)
 	 */
 	if (rt_task(current))
 		target = rq->active;
 
 	if (current->array->nr_active == 1) {
 		schedstat_inc(rq, yld_act_empty);
 		if (!rq->expired->nr_active)
 			schedstat_inc(rq, yld_both_empty);
 	} else if (!rq->expired->nr_active)
 		schedstat_inc(rq, yld_exp_empty);
 
 	dequeue_task(current, array);
 	enqueue_task(current, target);
 
 	/*
 	 * Since we are going to call schedule() anyway, there's
 	 * no need to preempt or enable interrupts:
 	 */
 	_raw_spin_unlock(&rq->lock);
 	preempt_enable_no_resched();
 
 	schedule();
 
 	return 0;
 }
 
 void __sched __cond_resched(void)
 {
 	set_current_state(TASK_RUNNING);
 	schedule();
 }
 
 EXPORT_SYMBOL(__cond_resched);
 
 /**
  * yield - yield the current processor to other threads.
  *
  * this is a shortcut for kernel-space yielding - it marks the
  * thread runnable and calls sys_sched_yield().
  */
 void __sched yield(void)
 {
 	set_current_state(TASK_RUNNING);
 	sys_sched_yield();
 }
 
 EXPORT_SYMBOL(yield);
 
 /*
  * This task is about to go to sleep on IO.  Increment rq->nr_iowait so
  * that process accounting knows that this is a task in IO wait state.
  *
  * But don't do that if it is a deliberate, throttling IO wait (this task
  * has set its backing_dev_info: the queue against which it should throttle)
  */
 void __sched io_schedule(void)
 {
 	struct runqueue *rq = this_rq();
 
 	atomic_inc(&rq->nr_iowait);
 	schedule();
 	atomic_dec(&rq->nr_iowait);
 }
 
 EXPORT_SYMBOL(io_schedule);
 
 long __sched io_schedule_timeout(long timeout)
 {
 	struct runqueue *rq = this_rq();
 	long ret;
 
 	atomic_inc(&rq->nr_iowait);
 	ret = schedule_timeout(timeout);
 	atomic_dec(&rq->nr_iowait);
 	return ret;
 }
 
 /**
  * sys_sched_get_priority_max - return maximum RT priority.
  * @policy: scheduling class.
  *
  * this syscall returns the maximum rt_priority that can be used
  * by a given scheduling class.
  */
 asmlinkage long sys_sched_get_priority_max(int policy)
 {
 	int ret = -EINVAL;
 
 	switch (policy) {
 	case SCHED_FIFO:
 	case SCHED_RR:
 		ret = MAX_USER_RT_PRIO-1;
 		break;
 	case SCHED_NORMAL:
 		ret = 0;
 		break;
 	}
 	return ret;
 }
 
 /**
  * sys_sched_get_priority_min - return minimum RT priority.
  * @policy: scheduling class.
  *
  * this syscall returns the minimum rt_priority that can be used
  * by a given scheduling class.
  */
 asmlinkage long sys_sched_get_priority_min(int policy)
 {
 	int ret = -EINVAL;
 
 	switch (policy) {
 	case SCHED_FIFO:
 	case SCHED_RR:
 		ret = 1;
 		break;
 	case SCHED_NORMAL:
 		ret = 0;
 	}
 	return ret;
 }
 
 /**
  * sys_sched_rr_get_interval - return the default timeslice of a process.
  * @pid: pid of the process.
  * @interval: userspace pointer to the timeslice value.
  *
  * this syscall writes the default timeslice value of a given process
  * into the user-space timespec buffer. A value of '0' means infinity.
  */
 asmlinkage
 long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
 {
 	int retval = -EINVAL;
 	struct timespec t;
 	task_t *p;
 
 	if (pid < 0)
 		goto out_nounlock;
 
 	retval = -ESRCH;
 	read_lock(&tasklist_lock);
 	p = find_process_by_pid(pid);
 	if (!p)
 		goto out_unlock;
 
 	retval = security_task_getscheduler(p);
 	if (retval)
 		goto out_unlock;
 
 	jiffies_to_timespec(p->policy & SCHED_FIFO ?
 				0 : task_timeslice(p), &t);
 	read_unlock(&tasklist_lock);
 	retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
 out_nounlock:
 	return retval;
 out_unlock:
 	read_unlock(&tasklist_lock);
 	return retval;
 }
 
 static inline struct task_struct *eldest_child(struct task_struct *p)
 {
 	if (list_empty(&p->children)) return NULL;
 	return list_entry(p->children.next,struct task_struct,sibling);
 }
 
 static inline struct task_struct *older_sibling(struct task_struct *p)
 {
 	if (p->sibling.prev==&p->parent->children) return NULL;
 	return list_entry(p->sibling.prev,struct task_struct,sibling);
 }
 
 static inline struct task_struct *younger_sibling(struct task_struct *p)
 {
 	if (p->sibling.next==&p->parent->children) return NULL;
 	return list_entry(p->sibling.next,struct task_struct,sibling);
 }
 
 static void show_task(task_t * p)
 {
 	task_t *relative;
 	unsigned state;
 	unsigned long free = 0;
 	static const char *stat_nam[] = { "R", "S", "D", "T", "t", "Z", "X" };
 
 	printk("%-13.13s ", p->comm);
 	state = p->state ? __ffs(p->state) + 1 : 0;
 	if (state < ARRAY_SIZE(stat_nam))
 		printk(stat_nam[state]);
 	else
 		printk("?");
 #if (BITS_PER_LONG == 32)
 	if (state == TASK_RUNNING)
 		printk(" running ");
 	else
 		printk(" %08lX ", thread_saved_pc(p));
 #else
 	if (state == TASK_RUNNING)
 		printk("  running task   ");
 	else
 		printk(" %016lx ", thread_saved_pc(p));
 #endif
 #ifdef CONFIG_DEBUG_STACK_USAGE
 	{
 		unsigned long * n = (unsigned long *) (p->thread_info+1);
 		while (!*n)
 			n++;
 		free = (unsigned long) n - (unsigned long)(p->thread_info+1);
 	}
 #endif
 	printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);
 	if ((relative = eldest_child(p)))
 		printk("%5d ", relative->pid);
 	else
 		printk("      ");
 	if ((relative = younger_sibling(p)))
 		printk("%7d", relative->pid);
 	else
 		printk("       ");
 	if ((relative = older_sibling(p)))
 		printk(" %5d", relative->pid);
 	else
 		printk("      ");
 	if (!p->mm)
 		printk(" (L-TLB)\n");
 	else
 		printk(" (NOTLB)\n");
 
 	if (state != TASK_RUNNING)
 		show_stack(p, NULL);
 }
 
 void show_state(void)
 {
 	task_t *g, *p;
 
 #if (BITS_PER_LONG == 32)
 	printk("\n"
 	       "                                               sibling\n");
 	printk("  task             PC      pid father child younger older\n");
 #else
 	printk("\n"
 	       "                                                       sibling\n");
 	printk("  task                 PC          pid father child younger older\n");
 #endif
 	read_lock(&tasklist_lock);
 	do_each_thread(g, p) {
 		/*
 		 * reset the NMI-timeout, listing all files on a slow
 		 * console might take alot of time:
 		 */
 		touch_nmi_watchdog();
 		show_task(p);
 	} while_each_thread(g, p);
 
 	read_unlock(&tasklist_lock);
 }
 
 void __devinit init_idle(task_t *idle, int cpu)
 {
 	runqueue_t *rq = cpu_rq(cpu);
 	unsigned long flags;
 
 	idle->sleep_avg = 0;
 	idle->interactive_credit = 0;
 	idle->array = NULL;
 	idle->prio = MAX_PRIO;
 	idle->state = TASK_RUNNING;
 	set_task_cpu(idle, cpu);
 
 	spin_lock_irqsave(&rq->lock, flags);
 	rq->curr = rq->idle = idle;
 	set_tsk_need_resched(idle);
 	spin_unlock_irqrestore(&rq->lock, flags);
 
 	/* Set the preempt count _outside_ the spinlocks! */
 #ifdef CONFIG_PREEMPT
 	idle->thread_info->preempt_count = (idle->lock_depth >= 0);
 #else
 	idle->thread_info->preempt_count = 0;
 #endif
 }
 
 /*
  * In a system that switches off the HZ timer nohz_cpu_mask
  * indicates which cpus entered this state. This is used
  * in the rcu update to wait only for active cpus. For system
  * which do not switch off the HZ timer nohz_cpu_mask should
  * always be CPU_MASK_NONE.
  */
 cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
 
 #ifdef CONFIG_SMP
 /*
  * This is how migration works:
  *
  * 1) we queue a migration_req_t structure in the source CPU's
  *    runqueue and wake up that CPU's migration thread.
  * 2) we down() the locked semaphore => thread blocks.
  * 3) migration thread wakes up (implicitly it forces the migrated
  *    thread off the CPU)
  * 4) it gets the migration request and checks whether the migrated
  *    task is still in the wrong runqueue.
  * 5) if it's in the wrong runqueue then the migration thread removes
  *    it and puts it into the right queue.
  * 6) migration thread up()s the semaphore.
  * 7) we wake up and the migration is done.
  */
 
 /*
  * Change a given task's CPU affinity. Migrate the thread to a
  * proper CPU and schedule it away if the CPU it's executing on
  * is removed from the allowed bitmask.
  *
  * NOTE: the caller must have a valid reference to the task, the
  * task must not exit() & deallocate itself prematurely.  The
  * call is not atomic; no spinlocks may be held.
  */
 int set_cpus_allowed(task_t *p, cpumask_t new_mask)
 {
 	unsigned long flags;
 	int ret = 0;
 	migration_req_t req;
 	runqueue_t *rq;
 
 	rq = task_rq_lock(p, &flags);
 	if (!cpus_intersects(new_mask, cpu_online_map)) {
 		ret = -EINVAL;
 		goto out;
 	}
 
 	p->cpus_allowed = new_mask;
 	/* Can the task run on the task's current CPU? If so, we're done */
 	if (cpu_isset(task_cpu(p), new_mask))
 		goto out;
 
 	if (migrate_task(p, any_online_cpu(new_mask), &req)) {
 		/* Need help from migration thread: drop lock and wait. */
 		task_rq_unlock(rq, &flags);
 		wake_up_process(rq->migration_thread);
 		wait_for_completion(&req.done);
 		tlb_migrate_finish(p->mm);
 		return 0;
 	}
 out:
 	task_rq_unlock(rq, &flags);
 	return ret;
 }
 
 EXPORT_SYMBOL_GPL(set_cpus_allowed);
 
 /*
  * Move (not current) task off this cpu, onto dest cpu.  We're doing
  * this because either it can't run here any more (set_cpus_allowed()
  * away from this CPU, or CPU going down), or because we're
  * attempting to rebalance this task on exec (sched_exec).
  *
  * So we race with normal scheduler movements, but that's OK, as long
  * as the task is no longer on this CPU.
  */
 static void __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
 {
 	runqueue_t *rq_dest, *rq_src;
 
 	if (unlikely(cpu_is_offline(dest_cpu)))
 		return;
 
 	rq_src = cpu_rq(src_cpu);
 	rq_dest = cpu_rq(dest_cpu);
 
 	double_rq_lock(rq_src, rq_dest);
 	/* Already moved. */
 	if (task_cpu(p) != src_cpu)
 		goto out;
 	/* Affinity changed (again). */
 	if (!cpu_isset(dest_cpu, p->cpus_allowed))
 		goto out;
 
 	set_task_cpu(p, dest_cpu);
 	if (p->array) {
 		/*
 		 * Sync timestamp with rq_dest's before activating.
 		 * The same thing could be achieved by doing this step
 		 * afterwards, and pretending it was a local activate.
 		 * This way is cleaner and logically correct.
 		 */
 		p->timestamp = p->timestamp - rq_src->timestamp_last_tick
 				+ rq_dest->timestamp_last_tick;
 		deactivate_task(p, rq_src);
 		activate_task(p, rq_dest, 0);
 		if (TASK_PREEMPTS_CURR(p, rq_dest))
 			resched_task(rq_dest->curr);
 	}
 
 out:
 	double_rq_unlock(rq_src, rq_dest);
 }
 
 /*
  * migration_thread - this is a highprio system thread that performs
  * thread migration by bumping thread off CPU then 'pushing' onto
  * another runqueue.
  */
 static int migration_thread(void * data)
 {
 	runqueue_t *rq;
 	int cpu = (long)data;
 
 	rq = cpu_rq(cpu);
 	BUG_ON(rq->migration_thread != current);
 
 	set_current_state(TASK_INTERRUPTIBLE);
 	while (!kthread_should_stop()) {
 		struct list_head *head;
 		migration_req_t *req;
 
 		if (current->flags & PF_FREEZE)
 			refrigerator(PF_FREEZE);
 
 		spin_lock_irq(&rq->lock);
 
 		if (cpu_is_offline(cpu)) {
 			spin_unlock_irq(&rq->lock);
 			goto wait_to_die;
 		}
 
 		if (rq->active_balance) {
 			active_load_balance(rq, cpu);
 			rq->active_balance = 0;
 		}
 
 		head = &rq->migration_queue;
 
 		if (list_empty(head)) {
 			spin_unlock_irq(&rq->lock);
 			schedule();
 			set_current_state(TASK_INTERRUPTIBLE);
 			continue;
 		}
 		req = list_entry(head->next, migration_req_t, list);
 		list_del_init(head->next);
 
 		if (req->type == REQ_MOVE_TASK) {
 			spin_unlock(&rq->lock);
 			__migrate_task(req->task, smp_processor_id(),
 					req->dest_cpu);
 			local_irq_enable();
 		} else if (req->type == REQ_SET_DOMAIN) {
 			rq->sd = req->sd;
 			spin_unlock_irq(&rq->lock);
 		} else {
 			spin_unlock_irq(&rq->lock);
 			WARN_ON(1);
 		}
 
 		complete(&req->done);
 	}
 	__set_current_state(TASK_RUNNING);
 	return 0;
 
 wait_to_die:
 	/* Wait for kthread_stop */
 	set_current_state(TASK_INTERRUPTIBLE);
 	while (!kthread_should_stop()) {
 		schedule();
 		set_current_state(TASK_INTERRUPTIBLE);
 	}
 	__set_current_state(TASK_RUNNING);
 	return 0;
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
 /* Figure out where task on dead CPU should go, use force if neccessary. */
 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *tsk)
 {
 	int dest_cpu;
 	cpumask_t mask;
 
 	/* On same node? */
 	mask = node_to_cpumask(cpu_to_node(dead_cpu));
 	cpus_and(mask, mask, tsk->cpus_allowed);
 	dest_cpu = any_online_cpu(mask);
 
 	/* On any allowed CPU? */
 	if (dest_cpu == NR_CPUS)
 		dest_cpu = any_online_cpu(tsk->cpus_allowed);
 
 	/* No more Mr. Nice Guy. */
 	if (dest_cpu == NR_CPUS) {
 		cpus_setall(tsk->cpus_allowed);
 		dest_cpu = any_online_cpu(tsk->cpus_allowed);
 
 		/*
 		 * Don't tell them about moving exiting tasks or
 		 * kernel threads (both mm NULL), since they never
 		 * leave kernel.
 		 */
 		if (tsk->mm && printk_ratelimit())
 			printk(KERN_INFO "process %d (%s) no "
 			       "longer affine to cpu%d\n",
 			       tsk->pid, tsk->comm, dead_cpu);
 	}
 	__migrate_task(tsk, dead_cpu, dest_cpu);
 }
 
 /* Run through task list and migrate tasks from the dead cpu. */
 static void migrate_live_tasks(int src_cpu)
 {
 	struct task_struct *tsk, *t;
 
 	write_lock_irq(&tasklist_lock);
 
 	do_each_thread(t, tsk) {
 		if (tsk == current)
 			continue;
 
 		if (task_cpu(tsk) == src_cpu)
 			move_task_off_dead_cpu(src_cpu, tsk);
 	} while_each_thread(t, tsk);
 
 	write_unlock_irq(&tasklist_lock);
 }
 
 /* Schedules idle task to be the next runnable task on current CPU.
  * It does so by boosting its priority to highest possible and adding it to
  * the _front_ of runqueue. Used by CPU offline code.
  */
 void sched_idle_next(void)
 {
 	int cpu = smp_processor_id();
 	runqueue_t *rq = this_rq();
 	struct task_struct *p = rq->idle;
 	unsigned long flags;
 
 	/* cpu has to be offline */
 	BUG_ON(cpu_online(cpu));
 
 	/* Strictly not necessary since rest of the CPUs are stopped by now
 	 * and interrupts disabled on current cpu.
 	 */
 	spin_lock_irqsave(&rq->lock, flags);
 
 	__setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
 	/* Add idle task to _front_ of it's priority queue */
 	__activate_idle_task(p, rq);
 
 	spin_unlock_irqrestore(&rq->lock, flags);
 }
 
 static void migrate_dead(unsigned int dead_cpu, task_t *tsk)
 {
 	struct runqueue *rq = cpu_rq(dead_cpu);
 
 	/* Must be exiting, otherwise would be on tasklist. */
 	BUG_ON(tsk->state != TASK_ZOMBIE && tsk->state != TASK_DEAD);
 
 	/* Cannot have done final schedule yet: would have vanished. */
 	BUG_ON(tsk->flags & PF_DEAD);
 
 	get_task_struct(tsk);
 
 	/*
 	 * Drop lock around migration; if someone else moves it,
 	 * that's OK.  No task can be added to this CPU, so iteration is
 	 * fine.
 	 */
 	spin_unlock_irq(&rq->lock);
 	move_task_off_dead_cpu(dead_cpu, tsk);
 	spin_lock_irq(&rq->lock);
 
 	put_task_struct(tsk);
 }
 
 /* release_task() removes task from tasklist, so we won't find dead tasks. */
 static void migrate_dead_tasks(unsigned int dead_cpu)
 {
 	unsigned arr, i;
 	struct runqueue *rq = cpu_rq(dead_cpu);
 
 	for (arr = 0; arr < 2; arr++) {
 		for (i = 0; i < MAX_PRIO; i++) {
 			struct list_head *list = &rq->arrays[arr].queue[i];
 			while (!list_empty(list))
 				migrate_dead(dead_cpu,
 					     list_entry(list->next, task_t,
 							run_list));
 		}
 	}
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
 /*
  * migration_call - callback that gets triggered when a CPU is added.
  * Here we can start up the necessary migration thread for the new CPU.
  */
 static int migration_call(struct notifier_block *nfb, unsigned long action,
 			  void *hcpu)
 {
 	int cpu = (long)hcpu;
 	struct task_struct *p;
 	struct runqueue *rq;
 	unsigned long flags;
 
 	switch (action) {
 	case CPU_UP_PREPARE:
 		p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
 		if (IS_ERR(p))
 			return NOTIFY_BAD;
 		p->flags |= PF_NOFREEZE;
 		kthread_bind(p, cpu);
 		/* Must be high prio: stop_machine expects to yield to it. */
 		rq = task_rq_lock(p, &flags);
 		__setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
 		task_rq_unlock(rq, &flags);
 		cpu_rq(cpu)->migration_thread = p;
 		break;
 	case CPU_ONLINE:
 		/* Strictly unneccessary, as first user will wake it. */
 		wake_up_process(cpu_rq(cpu)->migration_thread);
 		break;
 #ifdef CONFIG_HOTPLUG_CPU
 	case CPU_UP_CANCELED:
 		/* Unbind it from offline cpu so it can run.  Fall thru. */
 		kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id());
 		kthread_stop(cpu_rq(cpu)->migration_thread);
 		cpu_rq(cpu)->migration_thread = NULL;
 		break;
 	case CPU_DEAD:
 		migrate_live_tasks(cpu);
 		rq = cpu_rq(cpu);
 		kthread_stop(rq->migration_thread);
 		rq->migration_thread = NULL;
 		/* Idle task back to normal (off runqueue, low prio) */
 		rq = task_rq_lock(rq->idle, &flags);
 		deactivate_task(rq->idle, rq);
 		rq->idle->static_prio = MAX_PRIO;
 		__setscheduler(rq->idle, SCHED_NORMAL, 0);
 		migrate_dead_tasks(cpu);
 		task_rq_unlock(rq, &flags);
 		BUG_ON(rq->nr_running != 0);
 
 		/* No need to migrate the tasks: it was best-effort if
 		 * they didn't do lock_cpu_hotplug().  Just wake up
 		 * the requestors. */
 		spin_lock_irq(&rq->lock);
 		while (!list_empty(&rq->migration_queue)) {
 			migration_req_t *req;
 			req = list_entry(rq->migration_queue.next,
 					 migration_req_t, list);
 			BUG_ON(req->type != REQ_MOVE_TASK);
 			list_del_init(&req->list);
 			complete(&req->done);
 		}
 		spin_unlock_irq(&rq->lock);
 		break;
 #endif
 	}
 	return NOTIFY_OK;
 }
 
 /* Register at highest priority so that task migration (migrate_all_tasks)
  * happens before everything else.
  */
 static struct notifier_block __devinitdata migration_notifier = {
 	.notifier_call = migration_call,
 	.priority = 10
 };
 
 int __init migration_init(void)
 {
 	void *cpu = (void *)(long)smp_processor_id();
 	/* Start one for boot CPU. */
 	migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
 	migration_call(&migration_notifier, CPU_ONLINE, cpu);
 	register_cpu_notifier(&migration_notifier);
 	return 0;
 }
 #endif
 
 /*
  * The 'big kernel lock'
  *
  * This spinlock is taken and released recursively by lock_kernel()
  * and unlock_kernel().  It is transparently dropped and reaquired
  * over schedule().  It is used to protect legacy code that hasn't
  * been migrated to a proper locking design yet.
  *
  * Don't use in new code.
  *
  * Note: spinlock debugging needs this even on !CONFIG_SMP.
  */
 spinlock_t kernel_flag __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
 EXPORT_SYMBOL(kernel_flag);
 
 #ifdef CONFIG_SMP
 /* Attach the domain 'sd' to 'cpu' as its base domain */
 static void cpu_attach_domain(struct sched_domain *sd, int cpu)
 {
 	migration_req_t req;
 	unsigned long flags;
 	runqueue_t *rq = cpu_rq(cpu);
 	int local = 1;
 
 	lock_cpu_hotplug();
 
 	spin_lock_irqsave(&rq->lock, flags);
 
 	if (cpu == smp_processor_id() || !cpu_online(cpu)) {
 		rq->sd = sd;
 	} else {
 		init_completion(&req.done);
 		req.type = REQ_SET_DOMAIN;
 		req.sd = sd;
 		list_add(&req.list, &rq->migration_queue);
 		local = 0;
 	}
 
 	spin_unlock_irqrestore(&rq->lock, flags);
 
 	if (!local) {
 		wake_up_process(rq->migration_thread);
 		wait_for_completion(&req.done);
 	}
 
 	unlock_cpu_hotplug();
 }
 
 /*
  * To enable disjoint top-level NUMA domains, define SD_NODES_PER_DOMAIN
  * in arch code. That defines the number of nearby nodes in a node's top
  * level scheduling domain.
  */
 #if defined(CONFIG_NUMA) && defined(SD_NODES_PER_DOMAIN)
 /**
  * find_next_best_node - find the next node to include in a sched_domain
  * @node: node whose sched_domain we're building
  * @used_nodes: nodes already in the sched_domain
  *
  * Find the next node to include in a given scheduling domain.  Simply
  * finds the closest node not already in the @used_nodes map.
  *
  * Should use nodemask_t.
  */
 static int __init find_next_best_node(int node, unsigned long *used_nodes)
 {
 	int i, n, val, min_val, best_node = 0;
 
 	min_val = INT_MAX;
 
 	for (i = 0; i < numnodes; i++) {
 		/* Start at @node */
 		n = (node + i) % numnodes;
 
 		/* Skip already used nodes */
 		if (test_bit(n, used_nodes))
 			continue;
 
 		/* Simple min distance search */
 		val = node_distance(node, i);
 
 		if (val < min_val) {
 			min_val = val;
 			best_node = n;
 		}
 	}
 
 	set_bit(best_node, used_nodes);
 	return best_node;
 }
 
 /**
  * sched_domain_node_span - get a cpumask for a node's sched_domain
  * @node: node whose cpumask we're constructing
  * @size: number of nodes to include in this span
  *
  * Given a node, construct a good cpumask for its sched_domain to span.  It
  * should be one that prevents unnecessary balancing, but also spreads tasks
  * out optimally.
  */
 cpumask_t __init sched_domain_node_span(int node)
 {
 	int i;
 	cpumask_t span;
 	DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
 
 	cpus_clear(span);
 	bitmap_zero(used_nodes, MAX_NUMNODES);
 
 	for (i = 0; i < SD_NODES_PER_DOMAIN; i++) {
 		int next_node = find_next_best_node(node, used_nodes);
 		cpumask_t  nodemask;
 
 		nodemask = node_to_cpumask(next_node);
 		cpus_or(span, span, nodemask);
 	}
 
 	return span;
 }
 #else /* CONFIG_NUMA && SD_NODES_PER_DOMAIN */
 cpumask_t __init sched_domain_node_span(int node)
 {
 	return cpu_possible_map;
 }
 #endif /* CONFIG_NUMA && SD_NODES_PER_DOMAIN */
 
 #ifdef CONFIG_SCHED_SMT
 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
 static struct sched_group sched_group_cpus[NR_CPUS];
 __init static int cpu_to_cpu_group(int cpu)
 {
 	return cpu;
 }
 #endif
 
 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
 static struct sched_group sched_group_phys[NR_CPUS];
 __init static int cpu_to_phys_group(int cpu)
 {
 #ifdef CONFIG_SCHED_SMT
 	return first_cpu(cpu_sibling_map[cpu]);
 #else
 	return cpu;
 #endif
 }
 
 #ifdef CONFIG_NUMA
 
 static DEFINE_PER_CPU(struct sched_domain, node_domains);
 static struct sched_group sched_group_nodes[MAX_NUMNODES];
 __init static int cpu_to_node_group(int cpu)
 {
 	return cpu_to_node(cpu);
 }
 #endif
 
 /* Groups for isolated scheduling domains */
 static struct sched_group sched_group_isolated[NR_CPUS];
 
 /* cpus with isolated domains */
 cpumask_t __initdata cpu_isolated_map = CPU_MASK_NONE;
 
 __init static int cpu_to_isolated_group(int cpu)
 {
 	return cpu;
 }
 
 /* Setup the mask of cpus configured for isolated domains */
 static int __init isolated_cpu_setup(char *str)
 {
 	int ints[NR_CPUS], i;
 
 	str = get_options(str, ARRAY_SIZE(ints), ints);
 	cpus_clear(cpu_isolated_map);
 	for (i = 1; i <= ints[0]; i++)
 		cpu_set(ints[i], cpu_isolated_map);
 	return 1;
 }
 
 __setup ("isolcpus=", isolated_cpu_setup);
 
 /*
  * init_sched_build_groups takes an array of groups, the cpumask we wish
  * to span, and a pointer to a function which identifies what group a CPU
  * belongs to. The return value of group_fn must be a valid index into the
  * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
  * keep track of groups covered with a cpumask_t).
  *
  * init_sched_build_groups will build a circular linked list of the groups
  * covered by the given span, and will set each group's ->cpumask correctly,
  * and ->cpu_power to 0.
  */
 __init static void init_sched_build_groups(struct sched_group groups[],
 			cpumask_t span, int (*group_fn)(int cpu))
 {
 	struct sched_group *first = NULL, *last = NULL;
 	cpumask_t covered = CPU_MASK_NONE;
 	int i;
 
 	for_each_cpu_mask(i, span) {
 		int group = group_fn(i);
 		struct sched_group *sg = &groups[group];
 		int j;
 
 		if (cpu_isset(i, covered))
 			continue;
 
 		sg->cpumask = CPU_MASK_NONE;
 		sg->cpu_power = 0;
 
 		for_each_cpu_mask(j, span) {
 			if (group_fn(j) != group)
 				continue;
 
 			cpu_set(j, covered);
 			cpu_set(j, sg->cpumask);
 		}
 		if (!first)
 			first = sg;
 		if (last)
 			last->next = sg;
 		last = sg;
 	}
 	last->next = first;
 }
 
 __init static void arch_init_sched_domains(void)
 {
 	int i;
 	cpumask_t cpu_default_map;
 
 	/*
 	 * Setup mask for cpus without special case scheduling requirements.
 	 * For now this just excludes isolated cpus, but could be used to
 	 * exclude other special cases in the future.
 	 */
 	cpus_complement(cpu_default_map, cpu_isolated_map);
 	cpus_and(cpu_default_map, cpu_default_map, cpu_possible_map);
 
 	/* Set up domains */
 	for_each_cpu(i) {
 		int group;
 		struct sched_domain *sd = NULL, *p;
 		cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
 
 		cpus_and(nodemask, nodemask, cpu_default_map);
 
 		/*
 		 * Set up isolated domains.
 		 * Unlike those of other cpus, the domains and groups are
 		 * single level, and span a single cpu.
 		 */
 		if (cpu_isset(i, cpu_isolated_map)) {
 #ifdef CONFIG_SCHED_SMT
 			sd = &per_cpu(cpu_domains, i);
 #else
 			sd = &per_cpu(phys_domains, i);
 #endif
 			group = cpu_to_isolated_group(i);
 			*sd = SD_CPU_INIT;
 			cpu_set(i, sd->span);
 			sd->balance_interval = INT_MAX;	/* Don't balance */
 			sd->flags = 0;			/* Avoid WAKE_ */
 			sd->groups = &sched_group_isolated[group];
 			printk(KERN_INFO "Setting up cpu %d isolated.\n", i);
 			/* Single level, so continue with next cpu */
 			continue;
 		}
 
 #ifdef CONFIG_NUMA
 		sd = &per_cpu(node_domains, i);
 		group = cpu_to_node_group(i);
 		*sd = SD_NODE_INIT;
 		/* FIXME: should be multilevel, in arch code */
 		sd->span = sched_domain_node_span(i);
 		cpus_and(sd->span, sd->span, cpu_default_map);
 		sd->groups = &sched_group_nodes[group];
 #endif
 
 		p = sd;
 		sd = &per_cpu(phys_domains, i);
 		group = cpu_to_phys_group(i);
 		*sd = SD_CPU_INIT;
 #ifdef CONFIG_NUMA
 		sd->span = nodemask;
 #else
 		sd->span = cpu_possible_map;
 #endif
 		sd->parent = p;
 		sd->groups = &sched_group_phys[group];
 
 #ifdef CONFIG_SCHED_SMT
 		p = sd;
 		sd = &per_cpu(cpu_domains, i);
 		group = cpu_to_cpu_group(i);
 		*sd = SD_SIBLING_INIT;
 		sd->span = cpu_sibling_map[i];
 		cpus_and(sd->span, sd->span, cpu_default_map);
 		sd->parent = p;
 		sd->groups = &sched_group_cpus[group];
 #endif
 	}
 
 #ifdef CONFIG_SCHED_SMT
 	/* Set up CPU (sibling) groups */
 	for_each_cpu(i) {
 		cpumask_t this_sibling_map = cpu_sibling_map[i];
 		cpus_and(this_sibling_map, this_sibling_map, cpu_default_map);
 		if (i != first_cpu(this_sibling_map))
 			continue;
 
 		init_sched_build_groups(sched_group_cpus, this_sibling_map,
 						&cpu_to_cpu_group);
 	}
 #endif
 
 	/* Set up isolated groups */
 	for_each_cpu_mask(i, cpu_isolated_map) {
 		cpumask_t mask;
 		cpus_clear(mask);
 		cpu_set(i, mask);
 		init_sched_build_groups(sched_group_isolated, mask,
 						&cpu_to_isolated_group);
 	}
 
 #ifdef CONFIG_NUMA
 	/* Set up physical groups */
 	for (i = 0; i < MAX_NUMNODES; i++) {
 		cpumask_t nodemask = node_to_cpumask(i);
 
 		cpus_and(nodemask, nodemask, cpu_default_map);
 		if (cpus_empty(nodemask))
 			continue;
 
 		init_sched_build_groups(sched_group_phys, nodemask,
 						&cpu_to_phys_group);
 	}
 #else
 	init_sched_build_groups(sched_group_phys, cpu_possible_map,
 							&cpu_to_phys_group);
 #endif
 
 #ifdef CONFIG_NUMA
 	/* Set up node groups */
 	init_sched_build_groups(sched_group_nodes, cpu_default_map,
 					&cpu_to_node_group);
 #endif
 
 	/* Calculate CPU power for physical packages and nodes */
 	for_each_cpu_mask(i, cpu_default_map) {
 		int power;
 		struct sched_domain *sd;
 #ifdef CONFIG_SCHED_SMT
 		sd = &per_cpu(cpu_domains, i);
 		power = SCHED_LOAD_SCALE;
 		sd->groups->cpu_power = power;
 #endif
 
 		sd = &per_cpu(phys_domains, i);
 		power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
 				(cpus_weight(sd->groups->cpumask)-1) / 10;
 		sd->groups->cpu_power = power;
 
 #ifdef CONFIG_NUMA
 		if (i == first_cpu(sd->groups->cpumask)) {
 			/* Only add "power" once for each physical package. */
 			sd = &per_cpu(node_domains, i);
 			sd->groups->cpu_power += power;
 		}
 #endif
 	}
 
 	/* Attach the domains */
 	for_each_cpu(i) {
 		struct sched_domain *sd;
 #ifdef CONFIG_SCHED_SMT
 		sd = &per_cpu(cpu_domains, i);
 #else
 		sd = &per_cpu(phys_domains, i);
 #endif
 		cpu_attach_domain(sd, i);
 	}
 }
 
 #undef SCHED_DOMAIN_DEBUG
 #ifdef SCHED_DOMAIN_DEBUG
 void sched_domain_debug(void)
 {
 	int i;
 
 	for_each_cpu(i) {
 		runqueue_t *rq = cpu_rq(i);
 		struct sched_domain *sd;
 		int level = 0;
 
 		sd = rq->sd;
 
 		printk(KERN_DEBUG "CPU%d: %s\n",
 				i, (cpu_online(i) ? " online" : "offline"));
 
 		do {
 			int j;
 			char str[NR_CPUS];
 			struct sched_group *group = sd->groups;
 			cpumask_t groupmask;
 
 			cpumask_scnprintf(str, NR_CPUS, sd->span);
 			cpus_clear(groupmask);
 
 			printk(KERN_DEBUG);
 			for (j = 0; j < level + 1; j++)
 				printk(" ");
 			printk("domain %d: span %s\n", level, str);
 
 			if (!cpu_isset(i, sd->span))
 		printk(KERN_DEBUG "ERROR domain->span does not contain CPU%d\n", i);
 			if (!cpu_isset(i, group->cpumask))
 		printk(KERN_DEBUG "ERROR domain->groups does not contain CPU%d\n", i);
 			if (!group->cpu_power)
 				printk(KERN_DEBUG "ERROR domain->cpu_power not set\n");
 
 			printk(KERN_DEBUG);
 			for (j = 0; j < level + 2; j++)
 				printk(" ");
 			printk("groups:");
 			do {
 				if (!group) {
 					printk(" ERROR: NULL");
 					break;
 				}
 
 				if (!cpus_weight(group->cpumask))
 					printk(" ERROR empty group:");
 
 				if (cpus_intersects(groupmask, group->cpumask))
 					printk(" ERROR repeated CPUs:");
 
 				cpus_or(groupmask, groupmask, group->cpumask);
 
 				cpumask_scnprintf(str, NR_CPUS, group->cpumask);
 				printk(" %s", str);
 
 				group = group->next;
 			} while (group != sd->groups);
 			printk("\n");
 
 			if (!cpus_equal(sd->span, groupmask))
 	printk(KERN_DEBUG "ERROR groups don't span domain->span\n");
 
 			level++;
 			sd = sd->parent;
 
 			if (sd) {
 				if (!cpus_subset(groupmask, sd->span))
 	printk(KERN_DEBUG "ERROR parent span is not a superset of domain->span\n");
 			}
 
 		} while (sd);
 	}
 }
 #else
 #define sched_domain_debug() {}
 #endif
 
 void __init sched_init_smp(void)
 {
 	arch_init_sched_domains();
 	sched_domain_debug();
 }
 #else
 void __init sched_init_smp(void)
 {
 }
 #endif /* CONFIG_SMP */
 
 int in_sched_functions(unsigned long addr)
 {
 	/* Linker adds these: start and end of __sched functions */
 	extern char __sched_text_start[], __sched_text_end[];
 	return in_lock_functions(addr) ||
 		(addr >= (unsigned long)__sched_text_start
 		&& addr < (unsigned long)__sched_text_end);
 }
 
 void __init sched_init(void)
 {
 	runqueue_t *rq;
 	int i, j, k;
 
 #ifdef CONFIG_SMP
 	/* Set up an initial dummy domain for early boot */
 	static struct sched_domain sched_domain_init;
 	static struct sched_group sched_group_init;
 
 	memset(&sched_domain_init, 0, sizeof(struct sched_domain));
 	sched_domain_init.span = CPU_MASK_ALL;
 	sched_domain_init.groups = &sched_group_init;
 	sched_domain_init.last_balance = jiffies;
 	sched_domain_init.balance_interval = INT_MAX; /* Don't balance */
 	sched_domain_init.busy_factor = 1;
 
 	memset(&sched_group_init, 0, sizeof(struct sched_group));
 	sched_group_init.cpumask = CPU_MASK_ALL;
 	sched_group_init.next = &sched_group_init;
 	sched_group_init.cpu_power = SCHED_LOAD_SCALE;
 #endif
 
 	for (i = 0; i < NR_CPUS; i++) {
 		prio_array_t *array;
 
 		rq = cpu_rq(i);
 		spin_lock_init(&rq->lock);
 		rq->active = rq->arrays;
 		rq->expired = rq->arrays + 1;
 		rq->best_expired_prio = MAX_PRIO;
 
 #ifdef CONFIG_SMP
 		rq->sd = &sched_domain_init;
 		rq->cpu_load = 0;
 		rq->active_balance = 0;
 		rq->push_cpu = 0;
 		rq->migration_thread = NULL;
 		INIT_LIST_HEAD(&rq->migration_queue);
 #endif
 		atomic_set(&rq->nr_iowait, 0);
 
 		for (j = 0; j < 2; j++) {
 			array = rq->arrays + j;
 			for (k = 0; k < MAX_PRIO; k++) {
 				INIT_LIST_HEAD(array->queue + k);
 				__clear_bit(k, array->bitmap);
 			}
 			// delimiter for bitsearch
 			__set_bit(MAX_PRIO, array->bitmap);
 		}
 	}
 
 	/*
 	 * The boot idle thread does lazy MMU switching as well:
 	 */
 	atomic_inc(&init_mm.mm_count);
 	enter_lazy_tlb(&init_mm, current);
 
 	/*
 	 * Make us the idle thread. Technically, schedule() should not be
 	 * called from this thread, however somewhere below it might be,
 	 * but because we are the idle thread, we just pick up running again
 	 * when this runqueue becomes "idle".
 	 */
 	init_idle(current, smp_processor_id());
 }
 
 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
 void __might_sleep(char *file, int line)
 {
 #if defined(in_atomic)
 	static unsigned long prev_jiffy;	/* ratelimiting */
 
 	if ((in_atomic() || irqs_disabled()) &&
 	    system_state == SYSTEM_RUNNING) {
 		if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
 			return;
 		prev_jiffy = jiffies;
 		printk(KERN_ERR "Debug: sleeping function called from invalid"
 				" context at %s:%d\n", file, line);
 		printk("in_atomic():%d, irqs_disabled():%d\n",
 			in_atomic(), irqs_disabled());
 		dump_stack();
 	}
 #endif
 }
 EXPORT_SYMBOL(__might_sleep);
 #endif
 
 
 
Оставьте свой комментарий !

Ваше имя:
Комментарий:
Оба поля являются обязательными

 Автор  Комментарий к данной статье