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Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 5004 |
1 files changed, 5004 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c new file mode 100644 index 000000000000..f69c4a5361e3 --- /dev/null +++ b/kernel/sched.c @@ -0,0 +1,5004 @@ +/* + * kernel/sched.c + * + * Kernel scheduler and related syscalls + * + * Copyright (C) 1991-2002 Linus Torvalds + * + * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and + * make semaphores SMP safe + * 1998-11-19 Implemented schedule_timeout() and related stuff + * by Andrea Arcangeli + * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: + * hybrid priority-list and round-robin design with + * an array-switch method of distributing timeslices + * and per-CPU runqueues. Cleanups and useful suggestions + * by Davide Libenzi, preemptible kernel bits by Robert Love. + * 2003-09-03 Interactivity tuning by Con Kolivas. + * 2004-04-02 Scheduler domains code by Nick Piggin + */ + +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/nmi.h> +#include <linux/init.h> +#include <asm/uaccess.h> +#include <linux/highmem.h> +#include <linux/smp_lock.h> +#include <asm/mmu_context.h> +#include <linux/interrupt.h> +#include <linux/completion.h> +#include <linux/kernel_stat.h> +#include <linux/security.h> +#include <linux/notifier.h> +#include <linux/profile.h> +#include <linux/suspend.h> +#include <linux/blkdev.h> +#include <linux/delay.h> +#include <linux/smp.h> +#include <linux/threads.h> +#include <linux/timer.h> +#include <linux/rcupdate.h> +#include <linux/cpu.h> +#include <linux/cpuset.h> +#include <linux/percpu.h> +#include <linux/kthread.h> +#include <linux/seq_file.h> +#include <linux/syscalls.h> +#include <linux/times.h> +#include <linux/acct.h> +#include <asm/tlb.h> + +#include <asm/unistd.h> + +/* + * Convert user-nice values [ -20 ... 0 ... 19 ] + * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], + * and back. + */ +#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20) +#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20) +#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio) + +/* + * 'User priority' is the nice value converted to something we + * can work with better when scaling various scheduler parameters, + * it's a [ 0 ... 39 ] range. + */ +#define USER_PRIO(p) ((p)-MAX_RT_PRIO) +#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio) +#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO)) + +/* + * Some helpers for converting nanosecond timing to jiffy resolution + */ +#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ)) +#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ)) + +/* + * These are the 'tuning knobs' of the scheduler: + * + * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger), + * default timeslice is 100 msecs, maximum timeslice is 800 msecs. + * Timeslices get refilled after they expire. + */ +#define MIN_TIMESLICE max(5 * HZ / 1000, 1) +#define DEF_TIMESLICE (100 * HZ / 1000) +#define ON_RUNQUEUE_WEIGHT 30 +#define CHILD_PENALTY 95 +#define PARENT_PENALTY 100 +#define EXIT_WEIGHT 3 +#define PRIO_BONUS_RATIO 25 +#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100) +#define INTERACTIVE_DELTA 2 +#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS) +#define STARVATION_LIMIT (MAX_SLEEP_AVG) +#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG)) + +/* + * 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. + */ + +#define CURRENT_BONUS(p) \ + (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \ + MAX_SLEEP_AVG) + +#define GRANULARITY (10 * HZ / 1000 ? : 1) + +#ifdef CONFIG_SMP +#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ + (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \ + num_online_cpus()) +#else +#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ + (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1))) +#endif + +#define SCALE(v1,v1_max,v2_max) \ + (v1) * (v2_max) / (v1_max) + +#define DELTA(p) \ + (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA) + +#define TASK_INTERACTIVE(p) \ + ((p)->prio <= (p)->static_prio - DELTA(p)) + +#define INTERACTIVE_SLEEP(p) \ + (JIFFIES_TO_NS(MAX_SLEEP_AVG * \ + (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1)) + +#define TASK_PREEMPTS_CURR(p, rq) \ + ((p)->prio < (rq)->curr->prio) + +/* + * 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 inline 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) + +/* + * 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; + + /* + * This is part of a global counter where only the total sum + * over all CPUs matters. A task can increase this counter on + * one CPU and if it got migrated afterwards it may decrease + * it on another CPU. Always updated under the runqueue lock: + */ + unsigned long nr_uninterruptible; + + unsigned long expired_timestamp; + 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_switch; + unsigned long sched_cnt; + unsigned long sched_goidle; + + /* try_to_wake_up() stats */ + unsigned long ttwu_cnt; + unsigned long ttwu_local; +#endif +}; + +static DEFINE_PER_CPU(struct runqueue, runqueues); + +#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 inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags) + __acquires(rq->lock) +{ + 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) + __releases(rq->lock) +{ + 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 11 + +static int show_schedstat(struct seq_file *seq, void *v) +{ + int cpu; + + 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", + cpu, rq->yld_both_empty, + rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt, + rq->sched_switch, rq->sched_cnt, rq->sched_goidle, + rq->ttwu_cnt, rq->ttwu_local, + rq->rq_sched_info.cpu_time, + rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt); + + seq_printf(seq, "\n"); + +#ifdef CONFIG_SMP + /* domain-specific stats */ + for_each_domain(cpu, sd) { + enum idle_type itype; + char mask_str[NR_CPUS]; + + cpumask_scnprintf(mask_str, NR_CPUS, sd->span); + seq_printf(seq, "domain%d %s", dcnt++, mask_str); + for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES; + itype++) { + seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu", + sd->lb_cnt[itype], + sd->lb_balanced[itype], + sd->lb_failed[itype], + sd->lb_imbalance[itype], + sd->lb_gained[itype], + sd->lb_hot_gained[itype], + sd->lb_nobusyq[itype], + sd->lb_nobusyg[itype]); + } + seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu\n", + sd->alb_cnt, sd->alb_failed, sd->alb_pushed, + sd->sbe_pushed, sd->sbe_attempts, + sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_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) do { (rq)->field++; } while (0) +# define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0) +#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 inline runqueue_t *this_rq_lock(void) + __acquires(rq->lock) +{ + runqueue_t *rq; + + local_irq_disable(); + rq = this_rq(); + spin_lock(&rq->lock); + + return rq; +} + +#ifdef CONFIG_SCHED_SMT +static int cpu_and_siblings_are_idle(int cpu) +{ + int sib; + for_each_cpu_mask(sib, cpu_sibling_map[cpu]) { + if (idle_cpu(sib)) + continue; + return 0; + } + + return 1; +} +#else +#define cpu_and_siblings_are_idle(A) idle_cpu(A) +#endif + +#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; +} + +/* + * Put task to the end of the run list without the overhead of dequeue + * followed by enqueue. + */ +static void requeue_task(struct task_struct *p, prio_array_t *array) +{ + list_move_tail(&p->run_list, array->queue + p->prio); +} + +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) +{ + /* Caller must always ensure 'now >= p->timestamp' */ + 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); + } 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 waking from uninterruptible sleep are + * limited in their sleep_avg rise as they + * are likely to be waiting on I/O + */ + if (p->activated == -1 && 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; + } + } + + 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--; + 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; + + assert_spin_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 || task_running(rq, p))) { + /* 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.) + * + * NOTE: this function doesnt have to take the runqueue lock, + * because all it wants to ensure is that the remote task enters + * the kernel. If the IPI races and the task has been migrated + * to another CPU then no harm is done and the purpose has been + * achieved as well. + */ +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(); +} + +/* + * 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() will wake a task on an idle cpu if task->cpu is + * not idle and an idle cpu is available. The span of cpus to + * search starts with cpus closest then further out as needed, + * so we always favor a closer, idle cpu. + * + * 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; + struct sched_domain *sd; + int i; + + if (idle_cpu(cpu)) + return cpu; + + for_each_domain(cpu, sd) { + if (sd->flags & SD_WAKE_IDLE) { + 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; + } + } + else break; + } + 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); + 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; + +#ifdef CONFIG_SCHEDSTATS + schedstat_inc(rq, ttwu_cnt); + if (cpu == this_cpu) { + schedstat_inc(rq, ttwu_local); + } else { + for_each_domain(this_cpu, sd) { + if (cpu_isset(cpu, sd->span)) { + schedstat_inc(sd, ttwu_wake_remote); + break; + } + } + } +#endif + + 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_move_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_move_balance); + goto out_set_cpu; + } + } + } + + new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */ +out_set_cpu: + new_cpu = wake_idle(new_cpu, p); + if (new_cpu != cpu) { + 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(); + 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); + + /* + * 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->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); + + /* + * 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 inline void finish_task_switch(task_t *prev) + __releases(rq->lock) +{ + 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 EXIT_ZOMBIE in tsk->exit_state and + * calls schedule one last time. The schedule call will never return, + * and the scheduled task must drop that reference. + * The test for EXIT_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 <manfred@colorfullife.com> + */ + 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) + __releases(rq->lock) +{ + 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; + + /* + * Since we read the counters lockless, it might be slightly + * inaccurate. Do not allow it to go below zero though: + */ + if (unlikely((long)sum < 0)) + sum = 0; + + 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) + __acquires(rq1->lock) + __acquires(rq2->lock) +{ + if (rq1 == rq2) { + spin_lock(&rq1->lock); + __acquire(rq2->lock); /* Fake it out ;) */ + } 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) + __releases(rq1->lock) + __releases(rq2->lock) +{ + spin_unlock(&rq1->lock); + if (rq1 != rq2) + spin_unlock(&rq2->lock); + else + __release(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) + __releases(this_rq->lock) + __acquires(busiest->lock) + __acquires(this_rq->lock) +{ + 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, 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; + + /* 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(); + + /* 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: + * 1) the [whole] cpu is idle, or + * 2) too many balance attempts have failed. + */ + + if (cpu_and_siblings_are_idle(this_cpu) || \ + sd->nr_balance_failed > sd->cache_nice_tries) + return 1; + + 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; + } + +#ifdef CONFIG_SCHEDSTATS + if (task_hot(tmp, busiest->timestamp_last_tick, sd)) + schedstat_inc(sd, lb_hot_gained[idle]); +#endif + + 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: + /* + * 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_add(sd, lb_gained[idle], pulled); + 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 { + unsigned long load; + int local_group; + int i; + + local_group = cpu_isset(this_cpu, group->cpumask); + + /* Tally up the load of all CPUs in the group */ + avg_load = 0; + + for_each_cpu_mask(i, group->cpumask) { + /* Bias balancing toward cpus of our domain */ + if (local_group) + load = target_load(i); + else + load = source_load(i); + + avg_load += load; + } + + 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. + */ + /* How much load to actually move to equalise the imbalance */ + *imbalance = min((max_load - avg_load) * busiest->cpu_power, + (avg_load - this_load) * this->cpu_power) + / SCHED_LOAD_SCALE; + + if (*imbalance < SCHED_LOAD_SCALE) { + 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 */ + if (max_load*busiest->cpu_power < + SCHED_LOAD_SCALE*SCHED_LOAD_SCALE) + tmp = max_load*busiest->cpu_power/this->cpu_power; + else + tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power; + pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp); + pwr_move /= SCHED_LOAD_SCALE; + + /* Move if we gain throughput */ + if (pwr_move <= pwr_now) + goto out_balanced; + + *imbalance = 1; + return busiest; + } + + /* Get rid of the scaling factor, rounding down as we divide */ + *imbalance = *imbalance / SCHED_LOAD_SCALE; + + return busiest; + +out_balanced: + if (busiest && (idle == NEWLY_IDLE || + (idle == SCHED_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) +{ + unsigned long load, max_load = 0; + runqueue_t *busiest = NULL; + int i; + + for_each_cpu_mask(i, group->cpumask) { + 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; + } + + /* + * We were unbalanced, but unsuccessful in move_tasks(), + * so bump the balance_interval to lessen the lock contention. + */ + if (sd->balance_interval < sd->max_interval) + sd->balance_interval++; + } 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); + + schedstat_inc(sd, lb_balanced[idle]); + + /* 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_balanced[NEWLY_IDLE]); + schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]); + goto out; + } + + busiest = find_busiest_queue(group); + if (!busiest || busiest == this_rq) { + schedstat_inc(sd, lb_balanced[NEWLY_IDLE]); + 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 running tasks + * off the busiest CPU onto idle CPUs. It requires at least 1 task to be + * running on each physical CPU where possible, and avoids physical / + * logical imbalances. + * + * Called with busiest_rq locked. + */ +static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu) +{ + struct sched_domain *sd; + struct sched_group *cpu_group; + runqueue_t *target_rq; + cpumask_t visited_cpus; + int cpu; + + /* + * Search for suitable CPUs to push tasks to in successively higher + * domains with SD_LOAD_BALANCE set. + */ + visited_cpus = CPU_MASK_NONE; + for_each_domain(busiest_cpu, sd) { + if (!(sd->flags & SD_LOAD_BALANCE)) + /* no more domains to search */ + break; + + schedstat_inc(sd, alb_cnt); + + cpu_group = sd->groups; + do { + for_each_cpu_mask(cpu, cpu_group->cpumask) { + if (busiest_rq->nr_running <= 1) + /* no more tasks left to move */ + return; + if (cpu_isset(cpu, visited_cpus)) + continue; + cpu_set(cpu, visited_cpus); + if (!cpu_and_siblings_are_idle(cpu) || cpu == busiest_cpu) + continue; + + target_rq = cpu_rq(cpu); + /* + * This condition is "impossible", if it occurs + * we need to fix it. Originally reported by + * Bjorn Helgaas on a 128-cpu setup. + */ + BUG_ON(busiest_rq == target_rq); + + /* move a task from busiest_rq to target_rq */ + double_lock_balance(busiest_rq, target_rq); + if (move_tasks(target_rq, cpu, busiest_rq, + 1, sd, SCHED_IDLE)) { + schedstat_inc(sd, alb_pushed); + } else { + schedstat_inc(sd, alb_failed); + } + spin_unlock(&target_rq->lock); + } + cpu_group = cpu_group->next; + } while (cpu_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; + + if (!(sd->flags & SD_LOAD_BALANCE)) + continue; + + interval = sd->balance_interval; + if (idle != SCHED_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); + +/* + * This is called on clock ticks and on context switches. + * Bank in p->sched_time the ns elapsed since the last tick or switch. + */ +static inline void update_cpu_clock(task_t *p, runqueue_t *rq, + unsigned long long now) +{ + unsigned long long last = max(p->timestamp, rq->timestamp_last_tick); + p->sched_time += now - last; +} + +/* + * Return current->sched_time plus any more ns on the sched_clock + * that have not yet been banked. + */ +unsigned long long current_sched_time(const task_t *tsk) +{ + unsigned long long ns; + unsigned long flags; + local_irq_save(flags); + ns = max(tsk->timestamp, task_rq(tsk)->timestamp_last_tick); + ns = tsk->sched_time + (sched_clock() - ns); + local_irq_restore(flags); + return ns; +} + +/* + * 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)) + +/* + * Account user cpu time to a process. + * @p: the process that the cpu time gets accounted to + * @hardirq_offset: the offset to subtract from hardirq_count() + * @cputime: the cpu time spent in user space since the last update + */ +void account_user_time(struct task_struct *p, cputime_t cputime) +{ + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + cputime64_t tmp; + + p->utime = cputime_add(p->utime, cputime); + + /* Add user time to cpustat. */ + tmp = cputime_to_cputime64(cputime); + if (TASK_NICE(p) > 0) + cpustat->nice = cputime64_add(cpustat->nice, tmp); + else + cpustat->user = cputime64_add(cpustat->user, tmp); +} + +/* + * Account system cpu time to a process. + * @p: the process that the cpu time gets accounted to + * @hardirq_offset: the offset to subtract from hardirq_count() + * @cputime: the cpu time spent in kernel space since the last update + */ +void account_system_time(struct task_struct *p, int hardirq_offset, + cputime_t cputime) +{ + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + runqueue_t *rq = this_rq(); + cputime64_t tmp; + + p->stime = cputime_add(p->stime, cputime); + + /* Add system time to cpustat. */ + tmp = cputime_to_cputime64(cputime); + if (hardirq_count() - hardirq_offset) + cpustat->irq = cputime64_add(cpustat->irq, tmp); + else if (softirq_count()) + cpustat->softirq = cputime64_add(cpustat->softirq, tmp); + else if (p != rq->idle) + cpustat->system = cputime64_add(cpustat->system, tmp); + else if (atomic_read(&rq->nr_iowait) > 0) + cpustat->iowait = cputime64_add(cpustat->iowait, tmp); + else + cpustat->idle = cputime64_add(cpustat->idle, tmp); + /* Account for system time used */ + acct_update_integrals(p); + /* Update rss highwater mark */ + update_mem_hiwater(p); +} + +/* + * Account for involuntary wait time. + * @p: the process from which the cpu time has been stolen + * @steal: the cpu time spent in involuntary wait + */ +void account_steal_time(struct task_struct *p, cputime_t steal) +{ + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + cputime64_t tmp = cputime_to_cputime64(steal); + runqueue_t *rq = this_rq(); + + if (p == rq->idle) { + p->stime = cputime_add(p->stime, steal); + if (atomic_read(&rq->nr_iowait) > 0) + cpustat->iowait = cputime64_add(cpustat->iowait, tmp); + else + cpustat->idle = cputime64_add(cpustat->idle, tmp); + } else + cpustat->steal = cputime64_add(cpustat->steal, tmp); +} + +/* + * 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(void) +{ + int cpu = smp_processor_id(); + runqueue_t *rq = this_rq(); + task_t *p = current; + unsigned long long now = sched_clock(); + + update_cpu_clock(p, rq, now); + + rq->timestamp_last_tick = now; + + if (p == rq->idle) { + if (wake_priority_sleeper(rq)) + goto out; + rebalance_tick(cpu, rq, SCHED_IDLE); + return; + } + + /* 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: */ + requeue_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)) { + + requeue_task(p, rq->active); + set_tsk_need_resched(p); + } + } +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); + + sibling_map = sd->span; + + 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); + sibling_map = sd->span; + 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 + +#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT) + +void fastcall add_preempt_count(int val) +{ + /* + * Underflow? + */ + BUG_ON(((int)preempt_count() < 0)); + preempt_count() += val; + /* + * Spinlock count overflowing soon? + */ + BUG_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10); +} +EXPORT_SYMBOL(add_preempt_count); + +void fastcall sub_preempt_count(int val) +{ + /* + * Underflow? + */ + BUG_ON(val > preempt_count()); + /* + * Is the spinlock portion underflowing? + */ + BUG_ON((val < PREEMPT_MASK) && !(preempt_count() & PREEMPT_MASK)); + preempt_count() -= val; +} +EXPORT_SYMBOL(sub_preempt_count); + +#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->exit_state)) { + if (unlikely(in_atomic())) { + printk(KERN_ERR "scheduling while atomic: " + "%s/0x%08x/%d\n", + current->comm, preempt_count(), current->pid); + dump_stack(); + } + } + profile_hit(SCHED_PROFILING, __builtin_return_address(0)); + +need_resched: + preempt_disable(); + prev = current; + release_kernel_lock(prev); +need_resched_nonpreemptible: + rq = this_rq(); + + /* + * The idle thread is not allowed to schedule! + * Remove this check after it has been exercised a bit. + */ + if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) { + printk(KERN_ERR "bad: scheduling from the idle thread!\n"); + dump_stack(); + } + + schedstat_inc(rq, sched_cnt); + now = sched_clock(); + if (likely((long long)now - prev->timestamp < NS_MAX_SLEEP_AVG)) { + run_time = now - prev->timestamp; + if (unlikely((long long)now - prev->timestamp < 0)) + run_time = 0; + } else + run_time = NS_MAX_SLEEP_AVG; + + /* + * Tasks charged proportionately less run_time at high sleep_avg to + * delay them losing their interactive status + */ + run_time /= (CURRENT_BONUS(prev) ? : 1); + + spin_lock_irq(&rq->lock); + + if (unlikely(prev->flags & PF_DEAD)) + prev->state = EXIT_DEAD; + + 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 { + if (prev->state == TASK_UNINTERRUPTIBLE) + rq->nr_uninterruptible++; + 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)) { + 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; + } + + 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 (unlikely((long long)now - next->timestamp < 0)) + delta = 0; + + 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: + if (next == rq->idle) + schedstat_inc(rq, sched_goidle); + prefetch(next); + clear_tsk_need_resched(prev); + rcu_qsctr_inc(task_cpu(prev)); + + update_cpu_clock(prev, rq, now); + + prev->sleep_avg -= run_time; + if ((long)prev->sleep_avg <= 0) + prev->sleep_avg = 0; + 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); + + prev = current; + if (unlikely(reacquire_kernel_lock(prev) < 0)) + goto need_resched_nonpreemptible; + 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(); +#ifdef CONFIG_PREEMPT_BKL + struct task_struct *task = current; + int saved_lock_depth; +#endif + /* + * 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: + add_preempt_count(PREEMPT_ACTIVE); + /* + * We keep the big kernel semaphore locked, but we + * clear ->lock_depth so that schedule() doesnt + * auto-release the semaphore: + */ +#ifdef CONFIG_PREEMPT_BKL + saved_lock_depth = task->lock_depth; + task->lock_depth = -1; +#endif + schedule(); +#ifdef CONFIG_PREEMPT_BKL + task->lock_depth = saved_lock_depth; +#endif + sub_preempt_count(PREEMPT_ACTIVE); + + /* 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); + +/* + * this is is the entry point to schedule() from kernel preemption + * off of irq context. + * Note, that this is called and return with irqs disabled. This will + * protect us against recursive calling from irq. + */ +asmlinkage void __sched preempt_schedule_irq(void) +{ + struct thread_info *ti = current_thread_info(); +#ifdef CONFIG_PREEMPT_BKL + struct task_struct *task = current; + int saved_lock_depth; +#endif + /* Catch callers which need to be fixed*/ + BUG_ON(ti->preempt_count || !irqs_disabled()); + +need_resched: + add_preempt_count(PREEMPT_ACTIVE); + /* + * We keep the big kernel semaphore locked, but we + * clear ->lock_depth so that schedule() doesnt + * auto-release the semaphore: + */ +#ifdef CONFIG_PREEMPT_BKL + saved_lock_depth = task->lock_depth; + task->lock_depth = -1; +#endif + local_irq_enable(); + schedule(); + local_irq_disable(); +#ifdef CONFIG_PREEMPT_BKL + task->lock_depth = saved_lock_depth; +#endif + sub_preempt_count(PREEMPT_ACTIVE); + + /* we could miss a preemption opportunity between schedule and now */ + barrier(); + if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) + goto need_resched; +} + +#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); + +unsigned long fastcall __sched +wait_for_completion_timeout(struct completion *x, unsigned long timeout) +{ + 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); + timeout = schedule_timeout(timeout); + spin_lock_irq(&x->wait.lock); + if (!timeout) { + __remove_wait_queue(&x->wait, &wait); + goto out; + } + } while (!x->done); + __remove_wait_queue(&x->wait, &wait); + } + x->done--; +out: + spin_unlock_irq(&x->wait.lock); + return timeout; +} +EXPORT_SYMBOL(wait_for_completion_timeout); + +int fastcall __sched wait_for_completion_interruptible(struct completion *x) +{ + int ret = 0; + + 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 { + if (signal_pending(current)) { + ret = -ERESTARTSYS; + __remove_wait_queue(&x->wait, &wait); + goto out; + } + __set_current_state(TASK_INTERRUPTIBLE); + spin_unlock_irq(&x->wait.lock); + schedule(); + spin_lock_irq(&x->wait.lock); + } while (!x->done); + __remove_wait_queue(&x->wait, &wait); + } + x->done--; +out: + spin_unlock_irq(&x->wait.lock); + + return ret; +} +EXPORT_SYMBOL(wait_for_completion_interruptible); + +unsigned long fastcall __sched +wait_for_completion_interruptible_timeout(struct completion *x, + unsigned long timeout) +{ + 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 { + if (signal_pending(current)) { + timeout = -ERESTARTSYS; + __remove_wait_queue(&x->wait, &wait); + goto out; + } + __set_current_state(TASK_INTERRUPTIBLE); + spin_unlock_irq(&x->wait.lock); + timeout = schedule_timeout(timeout); + spin_lock_irq(&x->wait.lock); + if (!timeout) { + __remove_wait_queue(&x->wait, &wait); + goto out; + } + } while (!x->done); + __remove_wait_queue(&x->wait, &wait); + } + x->done--; +out: + spin_unlock_irq(&x->wait.lock); + return timeout; +} +EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); + + +#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 sched_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); +} + +/* + * The only users of task_nice are binfmt_elf and binfmt_elf32. + * binfmt_elf is no longer modular, but binfmt_elf32 still is. + * Therefore, task_nice is needed if there is a compat_mode. + */ +#ifdef CONFIG_COMPAT +EXPORT_SYMBOL_GPL(task_nice); +#endif + +/** + * 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); + +/** + * idle_task - return the idle task for a given cpu. + * @cpu: the processor in question. + */ +task_t *idle_task(int cpu) +{ + return cpu_rq(cpu)->idle; +} + +/** + * 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; +} + +/** + * sched_setscheduler - change the scheduling policy and/or RT priority of + * a thread. + * @p: the task in question. + * @policy: new policy. + * @param: structure containing the new RT priority. + */ +int sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param) +{ + int retval; + int oldprio, oldpolicy = -1; + prio_array_t *array; + unsigned long flags; + runqueue_t *rq; + +recheck: + /* double check policy once rq lock held */ + if (policy < 0) + policy = oldpolicy = p->policy; + else if (policy != SCHED_FIFO && policy != SCHED_RR && + policy != SCHED_NORMAL) + return -EINVAL; + /* + * Valid priorities for SCHED_FIFO and SCHED_RR are + * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0. + */ + if (param->sched_priority < 0 || + param->sched_priority > MAX_USER_RT_PRIO-1) + return -EINVAL; + if ((policy == SCHED_NORMAL) != (param->sched_priority == 0)) + return -EINVAL; + + if ((policy == SCHED_FIFO || policy == SCHED_RR) && + !capable(CAP_SYS_NICE)) + return -EPERM; + if ((current->euid != p->euid) && (current->euid != p->uid) && + !capable(CAP_SYS_NICE)) + return -EPERM; + + retval = security_task_setscheduler(p, policy, param); + if (retval) + return retval; + /* + * To be able to change p->policy safely, the apropriate + * runqueue lock must be held. + */ + rq = task_rq_lock(p, &flags); + /* recheck policy now with rq lock held */ + if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { + policy = oldpolicy = -1; + task_rq_unlock(rq, &flags); + goto recheck; + } + array = p->array; + if (array) + deactivate_task(p, rq); + oldprio = p->prio; + __setscheduler(p, policy, param->sched_priority); + if (array) { + __activate_task(p, rq); + /* + * 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); + } + task_rq_unlock(rq, &flags); + return 0; +} +EXPORT_SYMBOL_GPL(sched_setscheduler); + +static int do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) +{ + int retval; + struct sched_param lparam; + struct task_struct *p; + + if (!param || pid < 0) + return -EINVAL; + if (copy_from_user(&lparam, param, sizeof(struct sched_param))) + return -EFAULT; + read_lock_irq(&tasklist_lock); + p = find_process_by_pid(pid); + if (!p) { + read_unlock_irq(&tasklist_lock); + return -ESRCH; + } + retval = sched_setscheduler(p, policy, &lparam); + read_unlock_irq(&tasklist_lock); + 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 do_sched_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 do_sched_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; + cpumask_t cpus_allowed; + + 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; + + cpus_allowed = cpuset_cpus_allowed(p); + cpus_and(new_mask, new_mask, cpus_allowed); + 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); + + if (array != target) { + dequeue_task(current, array); + enqueue_task(current, target); + } else + /* + * requeue_task is cheaper so perform that if possible. + */ + requeue_task(current, array); + + /* + * Since we are going to call schedule() anyway, there's + * no need to preempt or enable interrupts: + */ + __release(rq->lock); + _raw_spin_unlock(&rq->lock); + preempt_enable_no_resched(); + + schedule(); + + return 0; +} + +static inline void __cond_resched(void) +{ + do { + add_preempt_count(PREEMPT_ACTIVE); + schedule(); + sub_preempt_count(PREEMPT_ACTIVE); + } while (need_resched()); +} + +int __sched cond_resched(void) +{ + if (need_resched()) { + __cond_resched(); + return 1; + } + return 0; +} + +EXPORT_SYMBOL(cond_resched); + +/* + * cond_resched_lock() - if a reschedule is pending, drop the given lock, + * call schedule, and on return reacquire the lock. + * + * This works OK both with and without CONFIG_PREEMPT. We do strange low-level + * operations here to prevent schedule() from being called twice (once via + * spin_unlock(), once by hand). + */ +int cond_resched_lock(spinlock_t * lock) +{ + if (need_lockbreak(lock)) { + spin_unlock(lock); + cpu_relax(); + spin_lock(lock); + } + if (need_resched()) { + _raw_spin_unlock(lock); + preempt_enable_no_resched(); + __cond_resched(); + spin_lock(lock); + return 1; + } + return 0; +} + +EXPORT_SYMBOL(cond_resched_lock); + +int __sched cond_resched_softirq(void) +{ + BUG_ON(!in_softirq()); + + if (need_resched()) { + __local_bh_enable(); + __cond_resched(); + local_bh_disable(); + return 1; + } + return 0; +} + +EXPORT_SYMBOL(cond_resched_softirq); + + +/** + * 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 = &per_cpu(runqueues, _smp_processor_id()); + + 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 = &per_cpu(runqueues, _smp_processor_id()); + 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->array = NULL; + idle->prio = MAX_PRIO; + idle->state = TASK_RUNNING; + idle->cpus_allowed = cpumask_of_cpu(cpu); + 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! */ +#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL) + 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, cpu, 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) { + tsk->cpus_allowed = cpuset_cpus_allowed(tsk); + 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); +} + +/* + * While a dead CPU has no uninterruptible tasks queued at this point, + * it might still have a nonzero ->nr_uninterruptible counter, because + * for performance reasons the counter is not stricly tracking tasks to + * their home CPUs. So we just add the counter to another CPU's counter, + * to keep the global sum constant after CPU-down: + */ +static void migrate_nr_uninterruptible(runqueue_t *rq_src) +{ + runqueue_t *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL)); + unsigned long flags; + + local_irq_save(flags); + double_rq_lock(rq_src, rq_dest); + rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible; + rq_src->nr_uninterruptible = 0; + double_rq_unlock(rq_src, rq_dest); + local_irq_restore(flags); +} + +/* 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); +} + +/* Ensures that the idle task is using init_mm right before its cpu goes + * offline. + */ +void idle_task_exit(void) +{ + struct mm_struct *mm = current->active_mm; + + BUG_ON(cpu_online(smp_processor_id())); + + if (mm != &init_mm) + switch_mm(mm, &init_mm, current); + mmdrop(mm); +} + +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->exit_state != EXIT_ZOMBIE && tsk->exit_state != EXIT_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); + migrate_nr_uninterruptible(rq); + 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 + +#ifdef CONFIG_SMP +#define SCHED_DOMAIN_DEBUG +#ifdef SCHED_DOMAIN_DEBUG +static void sched_domain_debug(struct sched_domain *sd, int cpu) +{ + int level = 0; + + printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); + + do { + int i; + 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 (i = 0; i < level + 1; i++) + printk(" "); + printk("domain %d: ", level); + + if (!(sd->flags & SD_LOAD_BALANCE)) { + printk("does not load-balance\n"); + if (sd->parent) + printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent"); + break; + } + + printk("span %s\n", str); + + if (!cpu_isset(cpu, sd->span)) + printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu); + if (!cpu_isset(cpu, group->cpumask)) + printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu); + + printk(KERN_DEBUG); + for (i = 0; i < level + 2; i++) + printk(" "); + printk("groups:"); + do { + if (!group) { + printk("\n"); + printk(KERN_ERR "ERROR: group is NULL\n"); + break; + } + + if (!group->cpu_power) { + printk("\n"); + printk(KERN_ERR "ERROR: domain->cpu_power not set\n"); + } + + if (!cpus_weight(group->cpumask)) { + printk("\n"); + printk(KERN_ERR "ERROR: empty group\n"); + } + + if (cpus_intersects(groupmask, group->cpumask)) { + printk("\n"); + printk(KERN_ERR "ERROR: repeated CPUs\n"); + } + + 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_ERR "ERROR: groups don't span domain->span\n"); + + level++; + sd = sd->parent; + + if (sd) { + if (!cpus_subset(groupmask, sd->span)) + printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n"); + } + + } while (sd); +} +#else +#define sched_domain_debug(sd, cpu) {} +#endif + +/* + * Attach the domain 'sd' to 'cpu' as its base domain. Callers must + * hold the hotplug lock. + */ +void __devinit 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; + + sched_domain_debug(sd, cpu); + + 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); + } +} + +/* cpus with isolated domains */ +cpumask_t __devinitdata cpu_isolated_map = CPU_MASK_NONE; + +/* 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++) + if (ints[i] < NR_CPUS) + 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. + */ +void __devinit 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; +} + + +#ifdef ARCH_HAS_SCHED_DOMAIN +extern void __devinit arch_init_sched_domains(void); +extern void __devinit arch_destroy_sched_domains(void); +#else +#ifdef CONFIG_SCHED_SMT +static DEFINE_PER_CPU(struct sched_domain, cpu_domains); +static struct sched_group sched_group_cpus[NR_CPUS]; +static int __devinit 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]; +static int __devinit 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]; +static int __devinit cpu_to_node_group(int cpu) +{ + return cpu_to_node(cpu); +} +#endif + +#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA) +/* + * The domains setup code relies on siblings not spanning + * multiple nodes. Make sure the architecture has a proper + * siblings map: + */ +static void check_sibling_maps(void) +{ + int i, j; + + for_each_online_cpu(i) { + for_each_cpu_mask(j, cpu_sibling_map[i]) { + if (cpu_to_node(i) != cpu_to_node(j)) { + printk(KERN_INFO "warning: CPU %d siblings map " + "to different node - isolating " + "them.\n", i); + cpu_sibling_map[i] = cpumask_of_cpu(i); + break; + } + } + } +} +#endif + +/* + * Set up scheduler domains and groups. Callers must hold the hotplug lock. + */ +static void __devinit arch_init_sched_domains(void) +{ + int i; + cpumask_t cpu_default_map; + +#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA) + check_sibling_maps(); +#endif + /* + * 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_online_map); + + /* + * Set up domains. Isolated domains just stay on the dummy domain. + */ + for_each_cpu_mask(i, cpu_default_map) { + 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); + +#ifdef CONFIG_NUMA + sd = &per_cpu(node_domains, i); + group = cpu_to_node_group(i); + *sd = SD_NODE_INIT; + 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; + sd->span = nodemask; + 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_online_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 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); + } + +#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_online_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); + } +} + +#ifdef CONFIG_HOTPLUG_CPU +static void __devinit arch_destroy_sched_domains(void) +{ + /* Do nothing: everything is statically allocated. */ +} +#endif + +#endif /* ARCH_HAS_SCHED_DOMAIN */ + +/* + * Initial dummy domain for early boot and for hotplug cpu. Being static, + * it is initialized to zero, so all balancing flags are cleared which is + * what we want. + */ +static struct sched_domain sched_domain_dummy; + +#ifdef CONFIG_HOTPLUG_CPU +/* + * Force a reinitialization of the sched domains hierarchy. The domains + * and groups cannot be updated in place without racing with the balancing + * code, so we temporarily attach all running cpus to a "dummy" domain + * which will prevent rebalancing while the sched domains are recalculated. + */ +static int update_sched_domains(struct notifier_block *nfb, + unsigned long action, void *hcpu) +{ + int i; + + switch (action) { + case CPU_UP_PREPARE: + case CPU_DOWN_PREPARE: + for_each_online_cpu(i) + cpu_attach_domain(&sched_domain_dummy, i); + arch_destroy_sched_domains(); + return NOTIFY_OK; + + case CPU_UP_CANCELED: + case CPU_DOWN_FAILED: + case CPU_ONLINE: + case CPU_DEAD: + /* + * Fall through and re-initialise the domains. + */ + break; + default: + return NOTIFY_DONE; + } + + /* The hotplug lock is already held by cpu_up/cpu_down */ + arch_init_sched_domains(); + + return NOTIFY_OK; +} +#endif + +void __init sched_init_smp(void) +{ + lock_cpu_hotplug(); + arch_init_sched_domains(); + unlock_cpu_hotplug(); + /* XXX: Theoretical race here - CPU may be hotplugged now */ + hotcpu_notifier(update_sched_domains, 0); +} +#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; + + 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_dummy; + 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 && !oops_in_progress) { + 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 + +#ifdef CONFIG_MAGIC_SYSRQ +void normalize_rt_tasks(void) +{ + struct task_struct *p; + prio_array_t *array; + unsigned long flags; + runqueue_t *rq; + + read_lock_irq(&tasklist_lock); + for_each_process (p) { + if (!rt_task(p)) + continue; + + rq = task_rq_lock(p, &flags); + + array = p->array; + if (array) + deactivate_task(p, task_rq(p)); + __setscheduler(p, SCHED_NORMAL, 0); + if (array) { + __activate_task(p, task_rq(p)); + resched_task(rq->curr); + } + + task_rq_unlock(rq, &flags); + } + read_unlock_irq(&tasklist_lock); +} + +#endif /* CONFIG_MAGIC_SYSRQ */ |