| /* |
| * 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/capability.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/vmalloc.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 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) |
| |
| void __put_task_struct_cb(struct rcu_head *rhp) |
| { |
| __put_task_struct(container_of(rhp, struct task_struct, rcu)); |
| } |
| |
| EXPORT_SYMBOL_GPL(__put_task_struct_cb); |
| |
| /* |
| * 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 prio_bias; |
| unsigned long cpu_load[3]; |
| #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); |
| |
| /* |
| * The domain tree (rq->sd) is protected by RCU's quiescent state transition. |
| * See detach_destroy_domains: synchronize_sched for details. |
| * |
| * The domain tree of any CPU may only be accessed from within |
| * preempt-disabled sections. |
| */ |
| #define for_each_domain(cpu, domain) \ |
| for (domain = rcu_dereference(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) |
| |
| #ifndef prepare_arch_switch |
| # define prepare_arch_switch(next) do { } while (0) |
| #endif |
| #ifndef finish_arch_switch |
| # define finish_arch_switch(prev) do { } while (0) |
| #endif |
| |
| #ifndef __ARCH_WANT_UNLOCKED_CTXSW |
| static inline int task_running(runqueue_t *rq, task_t *p) |
| { |
| return rq->curr == p; |
| } |
| |
| static inline void prepare_lock_switch(runqueue_t *rq, task_t *next) |
| { |
| } |
| |
| static inline void finish_lock_switch(runqueue_t *rq, task_t *prev) |
| { |
| #ifdef CONFIG_DEBUG_SPINLOCK |
| /* this is a valid case when another task releases the spinlock */ |
| rq->lock.owner = current; |
| #endif |
| spin_unlock_irq(&rq->lock); |
| } |
| |
| #else /* __ARCH_WANT_UNLOCKED_CTXSW */ |
| static inline int task_running(runqueue_t *rq, task_t *p) |
| { |
| #ifdef CONFIG_SMP |
| return p->oncpu; |
| #else |
| return rq->curr == p; |
| #endif |
| } |
| |
| static inline void prepare_lock_switch(runqueue_t *rq, task_t *next) |
| { |
| #ifdef CONFIG_SMP |
| /* |
| * We can optimise this out completely for !SMP, because the |
| * SMP rebalancing from interrupt is the only thing that cares |
| * here. |
| */ |
| next->oncpu = 1; |
| #endif |
| #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW |
| spin_unlock_irq(&rq->lock); |
| #else |
| spin_unlock(&rq->lock); |
| #endif |
| } |
| |
| static inline void finish_lock_switch(runqueue_t *rq, task_t *prev) |
| { |
| #ifdef CONFIG_SMP |
| /* |
| * After ->oncpu is cleared, the task can be moved to a different CPU. |
| * We must ensure this doesn't happen until the switch is completely |
| * finished. |
| */ |
| smp_wmb(); |
| prev->oncpu = 0; |
| #endif |
| #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW |
| local_irq_enable(); |
| #endif |
| } |
| #endif /* __ARCH_WANT_UNLOCKED_CTXSW */ |
| |
| /* |
| * 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 12 |
| |
| 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 */ |
| preempt_disable(); |
| 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 %lu %lu %lu %lu\n", |
| sd->alb_cnt, sd->alb_failed, sd->alb_pushed, |
| sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed, |
| sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed, |
| sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance); |
| } |
| preempt_enable(); |
| #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_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; |
| } |
| |
| #ifdef CONFIG_SMP |
| static inline void inc_prio_bias(runqueue_t *rq, int prio) |
| { |
| rq->prio_bias += MAX_PRIO - prio; |
| } |
| |
| static inline void dec_prio_bias(runqueue_t *rq, int prio) |
| { |
| rq->prio_bias -= MAX_PRIO - prio; |
| } |
| |
| static inline void inc_nr_running(task_t *p, runqueue_t *rq) |
| { |
| rq->nr_running++; |
| if (rt_task(p)) { |
| if (p != rq->migration_thread) |
| /* |
| * The migration thread does the actual balancing. Do |
| * not bias by its priority as the ultra high priority |
| * will skew balancing adversely. |
| */ |
| inc_prio_bias(rq, p->prio); |
| } else |
| inc_prio_bias(rq, p->static_prio); |
| } |
| |
| static inline void dec_nr_running(task_t *p, runqueue_t *rq) |
| { |
| rq->nr_running--; |
| if (rt_task(p)) { |
| if (p != rq->migration_thread) |
| dec_prio_bias(rq, p->prio); |
| } else |
| dec_prio_bias(rq, p->static_prio); |
| } |
| #else |
| static inline void inc_prio_bias(runqueue_t *rq, int prio) |
| { |
| } |
| |
| static inline void dec_prio_bias(runqueue_t *rq, int prio) |
| { |
| } |
| |
| static inline void inc_nr_running(task_t *p, runqueue_t *rq) |
| { |
| rq->nr_running++; |
| } |
| |
| static inline void dec_nr_running(task_t *p, runqueue_t *rq) |
| { |
| rq->nr_running--; |
| } |
| #endif |
| |
| /* |
| * __activate_task - move a task to the runqueue. |
| */ |
| static inline void __activate_task(task_t *p, runqueue_t *rq) |
| { |
| enqueue_task(p, rq->active); |
| inc_nr_running(p, rq); |
| } |
| |
| /* |
| * __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); |
| inc_nr_running(p, rq); |
| } |
| |
| static int 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; |
| } |
| } |
| |
| return 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 |
| |
| if (!rt_task(p)) |
| p->prio = 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) |
| { |
| dec_nr_running(p, rq); |
| 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 cpu; |
| |
| assert_spin_locked(&task_rq(p)->lock); |
| |
| if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED))) |
| return; |
| |
| set_tsk_thread_flag(p, TIF_NEED_RESCHED); |
| |
| cpu = task_cpu(p); |
| if (cpu == smp_processor_id()) |
| return; |
| |
| /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */ |
| smp_mb(); |
| if (!test_tsk_thread_flag(p, TIF_POLLING_NRFLAG)) |
| smp_send_reschedule(cpu); |
| } |
| #else |
| static inline void resched_task(task_t *p) |
| { |
| assert_spin_locked(&task_rq(p)->lock); |
| 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 |
| typedef struct { |
| struct list_head list; |
| |
| task_t *task; |
| int dest_cpu; |
| |
| 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->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, int type, enum idle_type idle) |
| { |
| runqueue_t *rq = cpu_rq(cpu); |
| unsigned long running = rq->nr_running; |
| unsigned long source_load, cpu_load = rq->cpu_load[type-1], |
| load_now = running * SCHED_LOAD_SCALE; |
| |
| if (type == 0) |
| source_load = load_now; |
| else |
| source_load = min(cpu_load, load_now); |
| |
| if (running > 1 || (idle == NOT_IDLE && running)) |
| /* |
| * If we are busy rebalancing the load is biased by |
| * priority to create 'nice' support across cpus. When |
| * idle rebalancing we should only bias the source_load if |
| * there is more than one task running on that queue to |
| * prevent idle rebalance from trying to pull tasks from a |
| * queue with only one running task. |
| */ |
| source_load = source_load * rq->prio_bias / running; |
| |
| return source_load; |
| } |
| |
| static inline unsigned long source_load(int cpu, int type) |
| { |
| return __source_load(cpu, type, NOT_IDLE); |
| } |
| |
| /* |
| * Return a high guess at the load of a migration-target cpu |
| */ |
| static inline unsigned long __target_load(int cpu, int type, enum idle_type idle) |
| { |
| runqueue_t *rq = cpu_rq(cpu); |
| unsigned long running = rq->nr_running; |
| unsigned long target_load, cpu_load = rq->cpu_load[type-1], |
| load_now = running * SCHED_LOAD_SCALE; |
| |
| if (type == 0) |
| target_load = load_now; |
| else |
| target_load = max(cpu_load, load_now); |
| |
| if (running > 1 || (idle == NOT_IDLE && running)) |
| target_load = target_load * rq->prio_bias / running; |
| |
| return target_load; |
| } |
| |
| static inline unsigned long target_load(int cpu, int type) |
| { |
| return __target_load(cpu, type, NOT_IDLE); |
| } |
| |
| /* |
| * find_idlest_group finds and returns the least busy CPU group within the |
| * domain. |
| */ |
| static struct sched_group * |
| find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) |
| { |
| struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups; |
| unsigned long min_load = ULONG_MAX, this_load = 0; |
| int load_idx = sd->forkexec_idx; |
| int imbalance = 100 + (sd->imbalance_pct-100)/2; |
| |
| do { |
| unsigned long load, avg_load; |
| int local_group; |
| int i; |
| |
| /* Skip over this group if it has no CPUs allowed */ |
| if (!cpus_intersects(group->cpumask, p->cpus_allowed)) |
| goto nextgroup; |
| |
| 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 = source_load(i, load_idx); |
| else |
| load = target_load(i, load_idx); |
| |
| avg_load += load; |
| } |
| |
| /* 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; |
| } else if (avg_load < min_load) { |
| min_load = avg_load; |
| idlest = group; |
| } |
| nextgroup: |
| group = group->next; |
| } while (group != sd->groups); |
| |
| if (!idlest || 100*this_load < imbalance*min_load) |
| return NULL; |
| return idlest; |
| } |
| |
| /* |
| * find_idlest_queue - find the idlest runqueue among the cpus in group. |
| */ |
| static int |
| find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) |
| { |
| cpumask_t tmp; |
| unsigned long load, min_load = ULONG_MAX; |
| int idlest = -1; |
| int i; |
| |
| /* Traverse only the allowed CPUs */ |
| cpus_and(tmp, group->cpumask, p->cpus_allowed); |
| |
| for_each_cpu_mask(i, tmp) { |
| load = source_load(i, 0); |
| |
| if (load < min_load || (load == min_load && i == this_cpu)) { |
| min_load = load; |
| idlest = i; |
| } |
| } |
| |
| return idlest; |
| } |
| |
| /* |
| * sched_balance_self: balance the current task (running on cpu) in domains |
| * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and |
| * SD_BALANCE_EXEC. |
| * |
| * Balance, ie. select the least loaded group. |
| * |
| * Returns the target CPU number, or the same CPU if no balancing is needed. |
| * |
| * preempt must be disabled. |
| */ |
| static int sched_balance_self(int cpu, int flag) |
| { |
| struct task_struct *t = current; |
| struct sched_domain *tmp, *sd = NULL; |
| |
| for_each_domain(cpu, tmp) |
| if (tmp->flags & flag) |
| sd = tmp; |
| |
| while (sd) { |
| cpumask_t span; |
| struct sched_group *group; |
| int new_cpu; |
| int weight; |
| |
| span = sd->span; |
| group = find_idlest_group(sd, t, cpu); |
| if (!group) |
| goto nextlevel; |
| |
| new_cpu = find_idlest_cpu(group, t, cpu); |
| if (new_cpu == -1 || new_cpu == cpu) |
| goto nextlevel; |
| |
| /* Now try balancing at a lower domain level */ |
| cpu = new_cpu; |
| nextlevel: |
| sd = NULL; |
| weight = cpus_weight(span); |
| for_each_domain(cpu, tmp) { |
| if (weight <= cpus_weight(tmp->span)) |
| break; |
| if (tmp->flags & flag) |
| sd = tmp; |
| } |
| /* while loop will break here if sd == NULL */ |
| } |
| |
| return cpu; |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| /* |
| * 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, 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, *this_sd = NULL; |
| 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; |
| |
| new_cpu = cpu; |
| |
| schedstat_inc(rq, ttwu_cnt); |
| if (cpu == this_cpu) { |
| schedstat_inc(rq, ttwu_local); |
| goto out_set_cpu; |
| } |
| |
| for_each_domain(this_cpu, sd) { |
| if (cpu_isset(cpu, sd->span)) { |
| schedstat_inc(sd, ttwu_wake_remote); |
| this_sd = sd; |
| break; |
| } |
| } |
| |
| if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed))) |
| goto out_set_cpu; |
| |
| /* |
| * Check for affine wakeup and passive balancing possibilities. |
| */ |
| if (this_sd) { |
| int idx = this_sd->wake_idx; |
| unsigned int imbalance; |
| |
| imbalance = 100 + (this_sd->imbalance_pct - 100) / 2; |
| |
| load = source_load(cpu, idx); |
| this_load = target_load(this_cpu, idx); |
| |
| new_cpu = this_cpu; /* Wake to this CPU if we can */ |
| |
| if (this_sd->flags & SD_WAKE_AFFINE) { |
| unsigned long tl = this_load; |
| /* |
| * If sync wakeup then subtract the (maximum possible) |
| * effect of the currently running task from the load |
| * of the current CPU: |
| */ |
| if (sync) |
| tl -= SCHED_LOAD_SCALE; |
| |
| if ((tl <= load && |
| tl + target_load(cpu, idx) <= SCHED_LOAD_SCALE) || |
| 100*(tl + SCHED_LOAD_SCALE) <= imbalance*load) { |
| /* |
| * This domain has SD_WAKE_AFFINE and |
| * p is cache cold in this domain, and |
| * there is no bad imbalance. |
| */ |
| schedstat_inc(this_sd, ttwu_move_affine); |
| goto out_set_cpu; |
| } |
| } |
| |
| /* |
| * Start passive balancing when half the imbalance_pct |
| * limit is reached. |
| */ |
| if (this_sd->flags & SD_WAKE_BALANCE) { |
| if (imbalance*this_load <= 100*load) { |
| schedstat_inc(this_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; |
| } |
| |
| /* |
| * Tasks that have marked their sleep as noninteractive get |
| * woken up without updating their sleep average. (i.e. their |
| * sleep is handled in a priority-neutral manner, no priority |
| * boost and no penalty.) |
| */ |
| if (old_state & TASK_NONINTERACTIVE) |
| __activate_task(p, rq); |
| else |
| activate_task(p, rq, cpu == this_cpu); |
| /* |
| * 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.) |
| */ |
| 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); |
| } |
| |
| /* |
| * Perform scheduler related setup for a newly forked process p. |
| * p is forked by current. |
| */ |
| void fastcall sched_fork(task_t *p, int clone_flags) |
| { |
| int cpu = get_cpu(); |
| |
| #ifdef CONFIG_SMP |
| cpu = sched_balance_self(cpu, SD_BALANCE_FORK); |
| #endif |
| set_task_cpu(p, cpu); |
| |
| /* |
| * 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; |
| #ifdef CONFIG_SCHEDSTATS |
| memset(&p->sched_info, 0, sizeof(p->sched_info)); |
| #endif |
| #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) |
| p->oncpu = 0; |
| #endif |
| #ifdef CONFIG_PREEMPT |
| /* Want to start with kernel preemption disabled. */ |
| task_thread_info(p)->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; |
| scheduler_tick(); |
| } |
| local_irq_enable(); |
| put_cpu(); |
| } |
| |
| /* |
| * 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); |
| BUG_ON(p->state != TASK_RUNNING); |
| this_cpu = smp_processor_id(); |
| cpu = task_cpu(p); |
| |
| /* |
| * 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++; |
| inc_nr_running(p, rq); |
| } |
| 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 && task_cpu(p) == task_cpu(p->parent)) { |
| 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); |
| } |
| |
| /** |
| * prepare_task_switch - prepare to switch tasks |
| * @rq: the runqueue preparing to switch |
| * @next: the task we are going to switch to. |
| * |
| * This is called with the rq lock held and interrupts off. It must |
| * be paired with a subsequent finish_task_switch after the context |
| * switch. |
| * |
| * prepare_task_switch sets up locking and calls architecture specific |
| * hooks. |
| */ |
| static inline void prepare_task_switch(runqueue_t *rq, task_t *next) |
| { |
| prepare_lock_switch(rq, next); |
| prepare_arch_switch(next); |
| } |
| |
| /** |
| * finish_task_switch - clean up after a task-switch |
| * @rq: runqueue associated with task-switch |
| * @prev: the thread we just switched away from. |
| * |
| * finish_task_switch must be called after the context switch, paired |
| * with a prepare_task_switch call before the context switch. |
| * finish_task_switch will reconcile locking set up by prepare_task_switch, |
| * and do 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(runqueue_t *rq, task_t *prev) |
| __releases(rq->lock) |
| { |
| 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(prev); |
| finish_lock_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) |
| { |
| runqueue_t *rq = this_rq(); |
| finish_task_switch(rq, prev); |
| #ifdef __ARCH_WANT_UNLOCKED_CTXSW |
| /* In this case, finish_task_switch does not reenable preemption */ |
| preempt_enable(); |
| #endif |
| 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); |
| } |
| } |
| |
| /* |
| * 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 - execve() is a valuable balancing opportunity, because at |
| * this point the task has the smallest effective memory and cache footprint. |
| */ |
| void sched_exec(void) |
| { |
| int new_cpu, this_cpu = get_cpu(); |
| new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC); |
| put_cpu(); |
| if (new_cpu != this_cpu) |
| sched_migrate_task(current, new_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); |
| dec_nr_running(p, src_rq); |
| set_task_cpu(p, this_cpu); |
| inc_nr_running(p, this_rq); |
| 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, |
| int *all_pinned) |
| { |
| /* |
| * 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 (!cpu_isset(this_cpu, p->cpus_allowed)) |
| return 0; |
| *all_pinned = 0; |
| |
| if (task_running(rq, p)) |
| return 0; |
| |
| /* |
| * Aggressive migration if: |
| * 1) task is cache cold, or |
| * 2) too many balance attempts have failed. |
| */ |
| |
| if (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, int *all_pinned) |
| { |
| prio_array_t *array, *dst_array; |
| struct list_head *head, *curr; |
| int idx, pulled = 0, pinned = 0; |
| task_t *tmp; |
| |
| if (max_nr_move == 0) |
| goto out; |
| |
| pinned = 1; |
| |
| /* |
| * 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, &pinned)) { |
| 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); |
| |
| if (all_pinned) |
| *all_pinned = pinned; |
| 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, int *sd_idle) |
| { |
| struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups; |
| unsigned long max_load, avg_load, total_load, this_load, total_pwr; |
| unsigned long max_pull; |
| int load_idx; |
| |
| max_load = this_load = total_load = total_pwr = 0; |
| if (idle == NOT_IDLE) |
| load_idx = sd->busy_idx; |
| else if (idle == NEWLY_IDLE) |
| load_idx = sd->newidle_idx; |
| else |
| load_idx = sd->idle_idx; |
| |
| 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) { |
| if (*sd_idle && !idle_cpu(i)) |
| *sd_idle = 0; |
| |
| /* Bias balancing toward cpus of our domain */ |
| if (local_group) |
| load = __target_load(i, load_idx, idle); |
| else |
| load = __source_load(i, load_idx, idle); |
| |
| 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; |
| } else if (avg_load > max_load) { |
| max_load = avg_load; |
| busiest = group; |
| } |
| group = group->next; |
| } while (group != sd->groups); |
| |
| if (!busiest || this_load >= max_load || max_load <= SCHED_LOAD_SCALE) |
| 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. |
| */ |
| |
| /* Don't want to pull so many tasks that a group would go idle */ |
| max_pull = min(max_load - avg_load, max_load - SCHED_LOAD_SCALE); |
| |
| /* How much load to actually move to equalise the imbalance */ |
| *imbalance = min(max_pull * 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: |
| |
| *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, |
| enum idle_type idle) |
| { |
| unsigned long load, max_load = 0; |
| runqueue_t *busiest = NULL; |
| int i; |
| |
| for_each_cpu_mask(i, group->cpumask) { |
| load = __source_load(i, 0, idle); |
| |
| if (load > max_load) { |
| max_load = load; |
| busiest = cpu_rq(i); |
| } |
| } |
| |
| return busiest; |
| } |
| |
| /* |
| * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but |
| * so long as it is large enough. |
| */ |
| #define MAX_PINNED_INTERVAL 512 |
| |
| /* |
| * 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, all_pinned = 0; |
| int active_balance = 0; |
| int sd_idle = 0; |
| |
| if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER) |
| sd_idle = 1; |
| |
| schedstat_inc(sd, lb_cnt[idle]); |
| |
| group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle); |
| if (!group) { |
| schedstat_inc(sd, lb_nobusyg[idle]); |
| goto out_balanced; |
| } |
| |
| busiest = find_busiest_queue(group, idle); |
| if (!busiest) { |
| schedstat_inc(sd, lb_nobusyq[idle]); |
| goto out_balanced; |
| } |
| |
| BUG_ON(busiest == this_rq); |
| |
| 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_rq_lock(this_rq, busiest); |
| nr_moved = move_tasks(this_rq, this_cpu, busiest, |
| imbalance, sd, idle, &all_pinned); |
| double_rq_unlock(this_rq, busiest); |
| |
| /* All tasks on this runqueue were pinned by CPU affinity */ |
| if (unlikely(all_pinned)) |
| goto out_balanced; |
| } |
| |
| if (!nr_moved) { |
| schedstat_inc(sd, lb_failed[idle]); |
| sd->nr_balance_failed++; |
| |
| if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) { |
| |
| spin_lock(&busiest->lock); |
| |
| /* don't kick the migration_thread, if the curr |
| * task on busiest cpu can't be moved to this_cpu |
| */ |
| if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) { |
| spin_unlock(&busiest->lock); |
| all_pinned = 1; |
| goto out_one_pinned; |
| } |
| |
| if (!busiest->active_balance) { |
| busiest->active_balance = 1; |
| busiest->push_cpu = this_cpu; |
| active_balance = 1; |
| } |
| spin_unlock(&busiest->lock); |
| if (active_balance) |
| wake_up_process(busiest->migration_thread); |
| |
| /* |
| * We've kicked active balancing, reset the failure |
| * counter. |
| */ |
| sd->nr_balance_failed = sd->cache_nice_tries+1; |
| } |
| } else |
| sd->nr_balance_failed = 0; |
| |
| if (likely(!active_balance)) { |
| /* We were unbalanced, so reset the balancing interval */ |
| sd->balance_interval = sd->min_interval; |
| } else { |
| /* |
| * If we've begun active balancing, start to back off. This |
| * case may not be covered by the all_pinned logic if there |
| * is only 1 task on the busy runqueue (because we don't call |
| * move_tasks). |
| */ |
| if (sd->balance_interval < sd->max_interval) |
| sd->balance_interval *= 2; |
| } |
| |
| if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER) |
| return -1; |
| return nr_moved; |
| |
| out_balanced: |
| schedstat_inc(sd, lb_balanced[idle]); |
| |
| sd->nr_balance_failed = 0; |
| |
| out_one_pinned: |
| /* tune up the balancing interval */ |
| if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) || |
| (sd->balance_interval < sd->max_interval)) |
| sd->balance_interval *= 2; |
| |
| if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER) |
| return -1; |
| 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; |
| int sd_idle = 0; |
| |
| if (sd->flags & SD_SHARE_CPUPOWER) |
| sd_idle = 1; |
| |
| schedstat_inc(sd, lb_cnt[NEWLY_IDLE]); |
| group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE, &sd_idle); |
| if (!group) { |
| schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]); |
| goto out_balanced; |
| } |
| |
| busiest = find_busiest_queue(group, NEWLY_IDLE); |
| if (!busiest) { |
| schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]); |
| goto out_balanced; |
| } |
| |
| BUG_ON(busiest == this_rq); |
| |
| schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance); |
| |
| nr_moved = 0; |
| if (busiest->nr_running > 1) { |
| /* Attempt to move tasks */ |
| double_lock_balance(this_rq, busiest); |
| nr_moved = move_tasks(this_rq, this_cpu, busiest, |
| imbalance, sd, NEWLY_IDLE, NULL); |
| spin_unlock(&busiest->lock); |
| } |
| |
| if (!nr_moved) { |
| schedstat_inc(sd, lb_failed[NEWLY_IDLE]); |
| if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER) |
| return -1; |
| } else |
| sd->nr_balance_failed = 0; |
| |
| return nr_moved; |
| |
| out_balanced: |
| schedstat_inc(sd, lb_balanced[NEWLY_IDLE]); |
| if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER) |
| return -1; |
| sd->nr_balance_failed = 0; |
| return 0; |
| } |
| |
| /* |
| * 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; |
| runqueue_t *target_rq; |
| int target_cpu = busiest_rq->push_cpu; |
| |
| if (busiest_rq->nr_running <= 1) |
| /* no task to move */ |
| return; |
| |
| target_rq = cpu_rq(target_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); |
| |
| /* Search for an sd spanning us and the target CPU. */ |
| for_each_domain(target_cpu, sd) |
| if ((sd->flags & SD_LOAD_BALANCE) && |
| cpu_isset(busiest_cpu, sd->span)) |
| break; |
| |
| if (unlikely(sd == NULL)) |
| goto out; |
| |
| schedstat_inc(sd, alb_cnt); |
| |
| if (move_tasks(target_rq, target_cpu, busiest_rq, 1, sd, SCHED_IDLE, NULL)) |
| schedstat_inc(sd, alb_pushed); |
| else |
| schedstat_inc(sd, alb_failed); |
| out: |
| spin_unlock(&target_rq->lock); |
| } |
| |
| /* |
| * 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; |
| int i; |
| |
| this_load = this_rq->nr_running * SCHED_LOAD_SCALE; |
| /* Update our load */ |
| for (i = 0; i < 3; i++) { |
| unsigned long new_load = this_load; |
| int scale = 1 << i; |
| old_load = this_rq->cpu_load[i]; |
| /* |
| * 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 (new_load > old_load) |
| new_load += scale-1; |
| this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale; |
| } |
| |
| 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 either we're no |
| * longer idle, or one of our SMT siblings is |
| * not 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); |
| } |
| |
| /* |
| * 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 wakeup_busy_runqueue(runqueue_t *rq) |
| { |
| /* If an SMT runqueue is sleeping due to priority reasons wake it up */ |
| if (rq->curr == rq->idle && rq->nr_running) |
| resched_task(rq->idle); |
| } |
| |
| static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq) |
| { |
| struct sched_domain *tmp, *sd = NULL; |
| cpumask_t sibling_map; |
| int i; |
| |
| for_each_domain(this_cpu, tmp) |
| if (tmp->flags & SD_SHARE_CPUPOWER) |
| sd = tmp; |
| |
| if (!sd) |
| 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); |
| |
| wakeup_busy_runqueue(smt_rq); |
| } |
| |
| 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: |
| */ |
| } |
| |
| /* |
| * number of 'lost' timeslices this task wont be able to fully |
| * utilize, if another task runs on a sibling. This models the |
| * slowdown effect of other tasks running on siblings: |
| */ |
| static inline unsigned long smt_slice(task_t *p, struct sched_domain *sd) |
| { |
| return p->time_slice * (100 - sd->per_cpu_gain) / 100; |
| } |
| |
| static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq) |
| { |
| struct sched_domain *tmp, *sd = NULL; |
| cpumask_t sibling_map; |
| prio_array_t *array; |
| int ret = 0, i; |
| task_t *p; |
| |
| for_each_domain(this_cpu, tmp) |
| if (tmp->flags & SD_SHARE_CPUPOWER) |
| sd = tmp; |
| |
| if (!sd) |
| 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; |
| |
| /* Kernel threads do not participate in dependent sleeping */ |
| if (!p->mm || !smt_curr->mm || rt_task(p)) |
| goto check_smt_task; |
| |
| /* |
| * 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 (rt_task(smt_curr)) { |
| /* |
| * With real time tasks we run non-rt tasks only |
| * per_cpu_gain% of the time. |
| */ |
| if ((jiffies % DEF_TIMESLICE) > |
| (sd->per_cpu_gain * DEF_TIMESLICE / 100)) |
| ret = 1; |
| } else |
| if (smt_curr->static_prio < p->static_prio && |
| !TASK_PREEMPTS_CURR(p, smt_rq) && |
| smt_slice(smt_curr, sd) > task_timeslice(p)) |
| ret = 1; |
| |
| check_smt_task: |
| if ((!smt_curr->mm && smt_curr != smt_rq->idle) || |
| rt_task(smt_curr)) |
| continue; |
| if (!p->mm) { |
| wakeup_busy_runqueue(smt_rq); |
| continue; |
| } |
| |
| /* |
| * Reschedule a lower priority task on the SMT sibling for |
| * it to be put to sleep, or wake it up if it has been put to |
| * sleep for priority reasons to see if it should run now. |
| */ |
| if (rt_task(p)) { |
| if ((jiffies % DEF_TIMESLICE) > |
| (sd->per_cpu_gain * DEF_TIMESLICE / 100)) |
| resched_task(smt_curr); |
| } else { |
| if (TASK_PREEMPTS_CURR(p, smt_rq) && |
| smt_slice(p, sd) > task_timeslice(smt_curr)) |
| resched_task(smt_curr); |
| else |
| wakeup_busy_runqueue(smt_rq); |
| } |
| } |
| 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((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, new_prio; |
| |
| /* |
| * 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; |
| new_prio = recalc_task_prio(next, next->timestamp + delta); |
| |
| if (unlikely(next->prio != new_prio)) { |
| dequeue_task(next, array); |
| next->prio = new_prio; |
| enqueue_task(next, array); |
| } else |
| requeue_task(next, array); |
| } |
| next->activated = 0; |
| switch_tasks: |
| if (next == rq->idle) |
| schedstat_inc(rq, sched_goidle); |
| prefetch(next); |
| prefetch_stack(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_task_switch(rq, next); |
| prev = context_switch(rq, prev, next); |
| barrier(); |
| /* |
| * this_rq must be evaluated again because prev may have moved |
| * CPUs since it called schedule(), thus the 'rq' on its stack |
| * frame will be invalid. |
| */ |
| finish_task_switch(this_rq(), 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->private; |
| 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 |
| * @key: is directly passed to the wakeup function |
| */ |
| 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); |
| dec_prio_bias(rq, p->static_prio); |
| } |
| |
| 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); |
| inc_prio_bias(rq, p->static_prio); |
| /* |
| * 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); |
| |
| /* |
| * can_nice - check if a task can reduce its nice value |
| * @p: task |
| * @nice: nice value |
| */ |
| int can_nice(const task_t *p, const int nice) |
| { |
| /* convert nice value [19,-20] to rlimit style value [1,40] */ |
| int nice_rlim = 20 - nice; |
| return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur || |
| capable(CAP_SYS_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 < -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; |
| |
| if (increment < 0 && !can_nice(current, nice)) |
| return -EPERM; |
| |
| retval = security_task_setnice(current, nice); |
| if (retval) |
| return retval; |
| |
| set_user_nice(current, nice); |
| return 0; |
| } |
| |
| #endif |
| |
| /** |
| * task_prio - return the priority value of a given task. |
| * @p: the task in question. |
| * |
| * This is the priority value as seen by users in /proc. |
| * RT tasks are offset by -200. Normal tasks are centered |
| * around 0, value goes from -16 to +15. |
| */ |
| int task_prio(const task_t *p) |
| { |
| return p->prio - MAX_RT_PRIO; |
| } |
| |
| /** |
| * task_nice - return the nice value of a given task. |
| * @p: the task in question. |
| */ |
| int task_nice(const task_t *p) |
| { |
| return TASK_NICE(p); |
| } |
| EXPORT_SYMBOL_GPL(task_nice); |
| |
| /** |
| * idle_cpu - is a given cpu idle currently? |
| * @cpu: the processor in question. |
| */ |
| int idle_cpu(int cpu) |
| { |
| return cpu_curr(cpu) == cpu_rq(cpu)->idle; |
| } |
| |
| /** |
| * 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_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 || |
| (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || |
| (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) |
| return -EINVAL; |
| if ((policy == SCHED_NORMAL) != (param->sched_priority == 0)) |
| return -EINVAL; |
| |
| /* |
| * Allow unprivileged RT tasks to decrease priority: |
| */ |
| if (!capable(CAP_SYS_NICE)) { |
| /* can't change policy */ |
| if (policy != p->policy && |
| !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) |
| return -EPERM; |
| /* can't increase priority */ |
| if (policy != SCHED_NORMAL && |
| param->sched_priority > p->rt_priority && |
| param->sched_priority > |
| p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) |
| return -EPERM; |
| /* can't change other user's priorities */ |
| if ((current->euid != p->euid) && |
| (current->euid != p->uid)) |
| 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 __read_mostly; |
| EXPORT_SYMBOL(cpu_present_map); |
| |
| #ifndef CONFIG_SMP |
| cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL; |
| cpumask_t cpu_possible_map __read_mostly = 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 (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) |
| { |
| /* |
| * The BKS might be reacquired before we have dropped |
| * PREEMPT_ACTIVE, which could trigger a second |
| * cond_resched() call. |
| */ |
| if (unlikely(preempt_count())) |
| return; |
| 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) |
| { |
| int ret = 0; |
| |
| if (need_lockbreak(lock)) { |
| spin_unlock(lock); |
| cpu_relax(); |
| ret = 1; |
| spin_lock(lock); |
| } |
| if (need_resched()) { |
| _raw_spin_unlock(lock); |
| preempt_enable_no_resched(); |
| __cond_resched(); |
| ret = 1; |
| spin_lock(lock); |
| } |
| return ret; |
| } |
| |
| 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, raw_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, raw_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 = end_of_stack(p); |
| while (!*n) |
| n++; |
| free = (unsigned long)n - (unsigned long)end_of_stack(p); |
| } |
| #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); |
| mutex_debug_show_all_locks(); |
| } |
| |
| /** |
| * init_idle - set up an idle thread for a given CPU |
| * @idle: task in question |
| * @cpu: cpu the idle task belongs to |
| * |
| * NOTE: this function does not set the idle thread's NEED_RESCHED |
| * flag, to make booting more robust. |
| */ |
| 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; |
| #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) |
| idle->oncpu = 1; |
| #endif |
| spin_unlock_irqrestore(&rq->lock, flags); |
| |
| /* Set the preempt count _outside_ the spinlocks! */ |
| #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL) |
| task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0); |
| #else |
| task_thread_info(idle)->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; |
| |
| try_to_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); |
| |
| spin_unlock(&rq->lock); |
| __migrate_task(req->task, cpu, req->dest_cpu); |
| local_irq_enable(); |
| |
| complete(&req->done); |
| } |
| __set_current_state(TASK_RUNNING); |
| return 0; |
| |
| wait_to_die: |
| /* Wait for kthread_stop */ |
| set_current_state(TASK_INTERRUPTIBLE); |
| while (!kthread_should_stop()) { |
| schedule(); |
| set_current_state(TASK_INTERRUPTIBLE); |
| } |
| __set_current_state(TASK_RUNNING); |
| return 0; |
| } |
| |
| #ifdef CONFIG_HOTPLUG_CPU |
| /* Figure out where task on dead CPU should go, use force if neccessary. */ |
| static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *tsk) |
| { |
| int dest_cpu; |
| cpumask_t mask; |
| |
| /* On same node? */ |
| mask = node_to_cpumask(cpu_to_node(dead_cpu)); |
| cpus_and(mask, mask, tsk->cpus_allowed); |
| dest_cpu = any_online_cpu(mask); |
| |
| /* On any allowed CPU? */ |
| if (dest_cpu == NR_CPUS) |
| dest_cpu = any_online_cpu(tsk->cpus_allowed); |
| |
| /* No more Mr. Nice Guy. */ |
| if (dest_cpu == NR_CPUS) { |
| cpus_setall(tsk->cpus_allowed); |
| dest_cpu = any_online_cpu(tsk->cpus_allowed); |
| |
| /* |
| * Don't tell them about moving exiting tasks or |
| * kernel threads (both mm NULL), since they never |
| * leave kernel. |
| */ |
| if (tsk->mm && printk_ratelimit()) |
| printk(KERN_INFO "process %d (%s) no " |
| "longer affine to cpu%d\n", |
| tsk->pid, tsk->comm, dead_cpu); |
| } |
| __migrate_task(tsk, dead_cpu, dest_cpu); |
| } |
| |
| /* |
| * 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, |
| any_online_cpu(cpu_online_map)); |
| 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); |
| 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 |
| #undef SCHED_DOMAIN_DEBUG |
| #ifdef SCHED_DOMAIN_DEBUG |
| static void sched_domain_debug(struct sched_domain *sd, int cpu) |
| { |
| int level = 0; |
| |
| if (!sd) { |
| printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); |
| return; |
| } |
| |
| 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 |
| |
| static int sd_degenerate(struct sched_domain *sd) |
| { |
| if (cpus_weight(sd->span) == 1) |
| return 1; |
| |
| /* Following flags need at least 2 groups */ |
| if (sd->flags & (SD_LOAD_BALANCE | |
| SD_BALANCE_NEWIDLE | |
| SD_BALANCE_FORK | |
| SD_BALANCE_EXEC)) { |
| if (sd->groups != sd->groups->next) |
| return 0; |
| } |
| |
| /* Following flags don't use groups */ |
| if (sd->flags & (SD_WAKE_IDLE | |
| SD_WAKE_AFFINE | |
| SD_WAKE_BALANCE)) |
| return 0; |
| |
| return 1; |
| } |
| |
| static int sd_parent_degenerate(struct sched_domain *sd, |
| struct sched_domain *parent) |
| { |
| unsigned long cflags = sd->flags, pflags = parent->flags; |
| |
| if (sd_degenerate(parent)) |
| return 1; |
| |
| if (!cpus_equal(sd->span, parent->span)) |
| return 0; |
| |
| /* Does parent contain flags not in child? */ |
| /* WAKE_BALANCE is a subset of WAKE_AFFINE */ |
| if (cflags & SD_WAKE_AFFINE) |
| pflags &= ~SD_WAKE_BALANCE; |
| /* Flags needing groups don't count if only 1 group in parent */ |
| if (parent->groups == parent->groups->next) { |
| pflags &= ~(SD_LOAD_BALANCE | |
| SD_BALANCE_NEWIDLE | |
| SD_BALANCE_FORK | |
| SD_BALANCE_EXEC); |
| } |
| if (~cflags & pflags) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * Attach the domain 'sd' to 'cpu' as its base domain. Callers must |
| * hold the hotplug lock. |
| */ |
| static void cpu_attach_domain(struct sched_domain *sd, int cpu) |
| { |
| runqueue_t *rq = cpu_rq(cpu); |
| struct sched_domain *tmp; |
| |
| /* Remove the sched domains which do not contribute to scheduling. */ |
| for (tmp = sd; tmp; tmp = tmp->parent) { |
| struct sched_domain *parent = tmp->parent; |
| if (!parent) |
| break; |
| if (sd_parent_degenerate(tmp, parent)) |
| tmp->parent = parent->parent; |
| } |
| |
| if (sd && sd_degenerate(sd)) |
| sd = sd->parent; |
| |
| sched_domain_debug(sd, cpu); |
| |
| rcu_assign_pointer(rq->sd, sd); |
| } |
| |
| /* cpus with isolated domains */ |
| static 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. |
| */ |
| static void init_sched_build_groups(struct sched_group groups[], cpumask_t span, |
| int (*group_fn)(int cpu)) |
| { |
| struct sched_group *first = NULL, *last = NULL; |
| cpumask_t covered = CPU_MASK_NONE; |
| int i; |
| |
| for_each_cpu_mask(i, span) { |
| int group = group_fn(i); |
| struct sched_group *sg = &groups[group]; |
| int j; |
| |
| if (cpu_isset(i, covered)) |
| continue; |
| |
| sg->cpumask = CPU_MASK_NONE; |
| sg->cpu_power = 0; |
| |
| for_each_cpu_mask(j, span) { |
| if (group_fn(j) != group) |
| continue; |
| |
| cpu_set(j, covered); |
| cpu_set(j, sg->cpumask); |
| } |
| if (!first) |
| first = sg; |
| if (last) |
| last->next = sg; |
| last = sg; |
| } |
| last->next = first; |
| } |
| |
| #define SD_NODES_PER_DOMAIN 16 |
| |
| /* |
| * Self-tuning task migration cost measurement between source and target CPUs. |
| * |
| * This is done by measuring the cost of manipulating buffers of varying |
| * sizes. For a given buffer-size here are the steps that are taken: |
| * |
| * 1) the source CPU reads+dirties a shared buffer |
| * 2) the target CPU reads+dirties the same shared buffer |
| * |
| * We measure how long they take, in the following 4 scenarios: |
| * |
| * - source: CPU1, target: CPU2 | cost1 |
| * - source: CPU2, target: CPU1 | cost2 |
| * - source: CPU1, target: CPU1 | cost3 |
| * - source: CPU2, target: CPU2 | cost4 |
| * |
| * We then calculate the cost3+cost4-cost1-cost2 difference - this is |
| * the cost of migration. |
| * |
| * We then start off from a small buffer-size and iterate up to larger |
| * buffer sizes, in 5% steps - measuring each buffer-size separately, and |
| * doing a maximum search for the cost. (The maximum cost for a migration |
| * normally occurs when the working set size is around the effective cache |
| * size.) |
| */ |
| #define SEARCH_SCOPE 2 |
| #define MIN_CACHE_SIZE (64*1024U) |
| #define DEFAULT_CACHE_SIZE (5*1024*1024U) |
| #define ITERATIONS 2 |
| #define SIZE_THRESH 130 |
| #define COST_THRESH 130 |
| |
| /* |
| * The migration cost is a function of 'domain distance'. Domain |
| * distance is the number of steps a CPU has to iterate down its |
| * domain tree to share a domain with the other CPU. The farther |
| * two CPUs are from each other, the larger the distance gets. |
| * |
| * Note that we use the distance only to cache measurement results, |
| * the distance value is not used numerically otherwise. When two |
| * CPUs have the same distance it is assumed that the migration |
| * cost is the same. (this is a simplification but quite practical) |
| */ |
| #define MAX_DOMAIN_DISTANCE 32 |
| |
| static unsigned long long migration_cost[MAX_DOMAIN_DISTANCE] = |
| { [ 0 ... MAX_DOMAIN_DISTANCE-1 ] = -1LL }; |
| |
| /* |
| * Allow override of migration cost - in units of microseconds. |
| * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost |
| * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs: |
| */ |
| static int __init migration_cost_setup(char *str) |
| { |
| int ints[MAX_DOMAIN_DISTANCE+1], i; |
| |
| str = get_options(str, ARRAY_SIZE(ints), ints); |
| |
| printk("#ints: %d\n", ints[0]); |
| for (i = 1; i <= ints[0]; i++) { |
| migration_cost[i-1] = (unsigned long long)ints[i]*1000; |
| printk("migration_cost[%d]: %Ld\n", i-1, migration_cost[i-1]); |
| } |
| return 1; |
| } |
| |
| __setup ("migration_cost=", migration_cost_setup); |
| |
| /* |
| * Global multiplier (divisor) for migration-cutoff values, |
| * in percentiles. E.g. use a value of 150 to get 1.5 times |
| * longer cache-hot cutoff times. |
| * |
| * (We scale it from 100 to 128 to long long handling easier.) |
| */ |
| |
| #define MIGRATION_FACTOR_SCALE 128 |
| |
| static unsigned int migration_factor = MIGRATION_FACTOR_SCALE; |
| |
| static int __init setup_migration_factor(char *str) |
| { |
| get_option(&str, &migration_factor); |
| migration_factor = migration_factor * MIGRATION_FACTOR_SCALE / 100; |
| return 1; |
| } |
| |
| __setup("migration_factor=", setup_migration_factor); |
| |
| /* |
| * Estimated distance of two CPUs, measured via the number of domains |
| * we have to pass for the two CPUs to be in the same span: |
| */ |
| static unsigned long domain_distance(int cpu1, int cpu2) |
| { |
| unsigned long distance = 0; |
| struct sched_domain *sd; |
| |
| for_each_domain(cpu1, sd) { |
| WARN_ON(!cpu_isset(cpu1, sd->span)); |
| if (cpu_isset(cpu2, sd->span)) |
| return distance; |
| distance++; |
| } |
| if (distance >= MAX_DOMAIN_DISTANCE) { |
| WARN_ON(1); |
| distance = MAX_DOMAIN_DISTANCE-1; |
| } |
| |
| return distance; |
| } |
| |
| static unsigned int migration_debug; |
| |
| static int __init setup_migration_debug(char *str) |
| { |
| get_option(&str, &migration_debug); |
| return 1; |
| } |
| |
| __setup("migration_debug=", setup_migration_debug); |
| |
| /* |
| * Maximum cache-size that the scheduler should try to measure. |
| * Architectures with larger caches should tune this up during |
| * bootup. Gets used in the domain-setup code (i.e. during SMP |
| * bootup). |
| */ |
| unsigned int max_cache_size; |
| |
| static int __init setup_max_cache_size(char *str) |
| { |
| get_option(&str, &max_cache_size); |
| return 1; |
| } |
| |
| __setup("max_cache_size=", setup_max_cache_size); |
| |
| /* |
| * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This |
| * is the operation that is timed, so we try to generate unpredictable |
| * cachemisses that still end up filling the L2 cache: |
| */ |
| static void touch_cache(void *__cache, unsigned long __size) |
| { |
| unsigned long size = __size/sizeof(long), chunk1 = size/3, |
| chunk2 = 2*size/3; |
| unsigned long *cache = __cache; |
| int i; |
| |
| for (i = 0; i < size/6; i += 8) { |
| switch (i % 6) { |
| case 0: cache[i]++; |
| case 1: cache[size-1-i]++; |
| case 2: cache[chunk1-i]++; |
| case 3: cache[chunk1+i]++; |
| case 4: cache[chunk2-i]++; |
| case 5: cache[chunk2+i]++; |
| } |
| } |
| } |
| |
| /* |
| * Measure the cache-cost of one task migration. Returns in units of nsec. |
| */ |
| static unsigned long long measure_one(void *cache, unsigned long size, |
| int source, int target) |
| { |
| cpumask_t mask, saved_mask; |
| unsigned long long t0, t1, t2, t3, cost; |
| |
| saved_mask = current->cpus_allowed; |
| |
| /* |
| * Flush source caches to RAM and invalidate them: |
| */ |
| sched_cacheflush(); |
| |
| /* |
| * Migrate to the source CPU: |
| */ |
| mask = cpumask_of_cpu(source); |
| set_cpus_allowed(current, mask); |
| WARN_ON(smp_processor_id() != source); |
| |
| /* |
| * Dirty the working set: |
| */ |
| t0 = sched_clock(); |
| touch_cache(cache, size); |
| t1 = sched_clock(); |
| |
| /* |
| * Migrate to the target CPU, dirty the L2 cache and access |
| * the shared buffer. (which represents the working set |
| * of a migrated task.) |
| */ |
| mask = cpumask_of_cpu(target); |
| set_cpus_allowed(current, mask); |
| WARN_ON(smp_processor_id() != target); |
| |
| t2 = sched_clock(); |
| touch_cache(cache, size); |
| t3 = sched_clock(); |
| |
| cost = t1-t0 + t3-t2; |
| |
| if (migration_debug >= 2) |
| printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n", |
| source, target, t1-t0, t1-t0, t3-t2, cost); |
| /* |
| * Flush target caches to RAM and invalidate them: |
| */ |
| sched_cacheflush(); |
| |
| set_cpus_allowed(current, saved_mask); |
| |
| return cost; |
| } |
| |
| /* |
| * Measure a series of task migrations and return the average |
| * result. Since this code runs early during bootup the system |
| * is 'undisturbed' and the average latency makes sense. |
| * |
| * The algorithm in essence auto-detects the relevant cache-size, |
| * so it will properly detect different cachesizes for different |
| * cache-hierarchies, depending on how the CPUs are connected. |
| * |
| * Architectures can prime the upper limit of the search range via |
| * max_cache_size, otherwise the search range defaults to 20MB...64K. |
| */ |
| static unsigned long long |
| measure_cost(int cpu1, int cpu2, void *cache, unsigned int size) |
| { |
| unsigned long long cost1, cost2; |
| int i; |
| |
| /* |
| * Measure the migration cost of 'size' bytes, over an |
| * average of 10 runs: |
| * |
| * (We perturb the cache size by a small (0..4k) |
| * value to compensate size/alignment related artifacts. |
| * We also subtract the cost of the operation done on |
| * the same CPU.) |
| */ |
| cost1 = 0; |
| |
| /* |
| * dry run, to make sure we start off cache-cold on cpu1, |
| * and to get any vmalloc pagefaults in advance: |
| */ |
| measure_one(cache, size, cpu1, cpu2); |
| for (i = 0; i < ITERATIONS; i++) |
| cost1 += measure_one(cache, size - i*1024, cpu1, cpu2); |
| |
| measure_one(cache, size, cpu2, cpu1); |
| for (i = 0; i < ITERATIONS; i++) |
| cost1 += measure_one(cache, size - i*1024, cpu2, cpu1); |
| |
| /* |
| * (We measure the non-migrating [cached] cost on both |
| * cpu1 and cpu2, to handle CPUs with different speeds) |
| */ |
| cost2 = 0; |
| |
| measure_one(cache, size, cpu1, cpu1); |
| for (i = 0; i < ITERATIONS; i++) |
| cost2 += measure_one(cache, size - i*1024, cpu1, cpu1); |
| |
| measure_one(cache, size, cpu2, cpu2); |
| for (i = 0; i < ITERATIONS; i++) |
| cost2 += measure_one(cache, size - i*1024, cpu2, cpu2); |
| |
| /* |
| * Get the per-iteration migration cost: |
| */ |
| do_div(cost1, 2*ITERATIONS); |
| do_div(cost2, 2*ITERATIONS); |
| |
| return cost1 - cost2; |
| } |
| |
| static unsigned long long measure_migration_cost(int cpu1, int cpu2) |
| { |
| unsigned long long max_cost = 0, fluct = 0, avg_fluct = 0; |
| unsigned int max_size, size, size_found = 0; |
| long long cost = 0, prev_cost; |
| void *cache; |
| |
| /* |
| * Search from max_cache_size*5 down to 64K - the real relevant |
| * cachesize has to lie somewhere inbetween. |
| */ |
| if (max_cache_size) { |
| max_size = max(max_cache_size * SEARCH_SCOPE, MIN_CACHE_SIZE); |
| size = max(max_cache_size / SEARCH_SCOPE, MIN_CACHE_SIZE); |
| } else { |
| /* |
| * Since we have no estimation about the relevant |
| * search range |
| */ |
| max_size = DEFAULT_CACHE_SIZE * SEARCH_SCOPE; |
| size = MIN_CACHE_SIZE; |
| } |
| |
| if (!cpu_online(cpu1) || !cpu_online(cpu2)) { |
| printk("cpu %d and %d not both online!\n", cpu1, cpu2); |
| return 0; |
| } |
| |
| /* |
| * Allocate the working set: |
| */ |
| cache = vmalloc(max_size); |
| if (!cache) { |
| printk("could not vmalloc %d bytes for cache!\n", 2*max_size); |
| return 1000000; // return 1 msec on very small boxen |
| } |
| |
| while (size <= max_size) { |
| prev_cost = cost; |
| cost = measure_cost(cpu1, cpu2, cache, size); |
| |
| /* |
| * Update the max: |
| */ |
| if (cost > 0) { |
| if (max_cost < cost) { |
| max_cost = cost; |
| size_found = size; |
| } |
| } |
| /* |
| * Calculate average fluctuation, we use this to prevent |
| * noise from triggering an early break out of the loop: |
| */ |
| fluct = abs(cost - prev_cost); |
| avg_fluct = (avg_fluct + fluct)/2; |
| |
| if (migration_debug) |
| printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): (%8Ld %8Ld)\n", |
| cpu1, cpu2, size, |
| (long)cost / 1000000, |
| ((long)cost / 100000) % 10, |
| (long)max_cost / 1000000, |
| ((long)max_cost / 100000) % 10, |
| domain_distance(cpu1, cpu2), |
| cost, avg_fluct); |
| |
| /* |
| * If we iterated at least 20% past the previous maximum, |
| * and the cost has dropped by more than 20% already, |
| * (taking fluctuations into account) then we assume to |
| * have found the maximum and break out of the loop early: |
| */ |
| if (size_found && (size*100 > size_found*SIZE_THRESH)) |
| if (cost+avg_fluct <= 0 || |
| max_cost*100 > (cost+avg_fluct)*COST_THRESH) { |
| |
| if (migration_debug) |
| printk("-> found max.\n"); |
| break; |
| } |
| /* |
| * Increase the cachesize in 5% steps: |
| */ |
| size = size * 20 / 19; |
| } |
| |
| if (migration_debug) |
| printk("[%d][%d] working set size found: %d, cost: %Ld\n", |
| cpu1, cpu2, size_found, max_cost); |
| |
| vfree(cache); |
| |
| /* |
| * A task is considered 'cache cold' if at least 2 times |
| * the worst-case cost of migration has passed. |
| * |
| * (this limit is only listened to if the load-balancing |
| * situation is 'nice' - if there is a large imbalance we |
| * ignore it for the sake of CPU utilization and |
| * processing fairness.) |
| */ |
| return 2 * max_cost * migration_factor / MIGRATION_FACTOR_SCALE; |
| } |
| |
| static void calibrate_migration_costs(const cpumask_t *cpu_map) |
| { |
| int cpu1 = -1, cpu2 = -1, cpu, orig_cpu = raw_smp_processor_id(); |
| unsigned long j0, j1, distance, max_distance = 0; |
| struct sched_domain *sd; |
| |
| j0 = jiffies; |
| |
| /* |
| * First pass - calculate the cacheflush times: |
| */ |
| for_each_cpu_mask(cpu1, *cpu_map) { |
| for_each_cpu_mask(cpu2, *cpu_map) { |
| if (cpu1 == cpu2) |
| continue; |
| distance = domain_distance(cpu1, cpu2); |
| max_distance = max(max_distance, distance); |
| /* |
| * No result cached yet? |
| */ |
| if (migration_cost[distance] == -1LL) |
| migration_cost[distance] = |
| measure_migration_cost(cpu1, cpu2); |
| } |
| } |
| /* |
| * Second pass - update the sched domain hierarchy with |
| * the new cache-hot-time estimations: |
| */ |
| for_each_cpu_mask(cpu, *cpu_map) { |
| distance = 0; |
| for_each_domain(cpu, sd) { |
| sd->cache_hot_time = migration_cost[distance]; |
| distance++; |
| } |
| } |
| /* |
| * Print the matrix: |
| */ |
| if (migration_debug) |
| printk("migration: max_cache_size: %d, cpu: %d MHz:\n", |
| max_cache_size, |
| #ifdef CONFIG_X86 |
| cpu_khz/1000 |
| #else |
| -1 |
| #endif |
| ); |
| printk("migration_cost="); |
| for (distance = 0; distance <= max_distance; distance++) { |
| if (distance) |
| printk(","); |
| printk("%ld", (long)migration_cost[distance] / 1000); |
| } |
| printk("\n"); |
| j1 = jiffies; |
| if (migration_debug) |
| printk("migration: %ld seconds\n", (j1-j0)/HZ); |
| |
| /* |
| * Move back to the original CPU. NUMA-Q gets confused |
| * if we migrate to another quad during bootup. |
| */ |
| if (raw_smp_processor_id() != orig_cpu) { |
| cpumask_t mask = cpumask_of_cpu(orig_cpu), |
| saved_mask = current->cpus_allowed; |
| |
| set_cpus_allowed(current, mask); |
| set_cpus_allowed(current, saved_mask); |
| } |
| } |
| |
| #ifdef CONFIG_NUMA |
| |
| /** |
| * find_next_best_node - find the next node to include in a sched_domain |
| * @node: node whose sched_domain we're building |
| * @used_nodes: nodes already in the sched_domain |
| * |
| * Find the next node to include in a given scheduling domain. Simply |
| * finds the closest node not already in the @used_nodes map. |
| * |
| * Should use nodemask_t. |
| */ |
| static int find_next_best_node(int node, unsigned long *used_nodes) |
| { |
| int i, n, val, min_val, best_node = 0; |
| |
| min_val = INT_MAX; |
| |
| for (i = 0; i < MAX_NUMNODES; i++) { |
| /* Start at @node */ |
| n = (node + i) % MAX_NUMNODES; |
| |
| if (!nr_cpus_node(n)) |
| continue; |
| |
| /* Skip already used nodes */ |
| if (test_bit(n, used_nodes)) |
| continue; |
| |
| /* Simple min distance search */ |
| val = node_distance(node, n); |
| |
| if (val < min_val) { |
| min_val = val; |
| best_node = n; |
| } |
| } |
| |
| set_bit(best_node, used_nodes); |
| return best_node; |
| } |
| |
| /** |
| * sched_domain_node_span - get a cpumask for a node's sched_domain |
| * @node: node whose cpumask we're constructing |
| * @size: number of nodes to include in this span |
| * |
| * Given a node, construct a good cpumask for its sched_domain to span. It |
| * should be one that prevents unnecessary balancing, but also spreads tasks |
| * out optimally. |
| */ |
| static cpumask_t sched_domain_node_span(int node) |
| { |
| int i; |
| cpumask_t span, nodemask; |
| DECLARE_BITMAP(used_nodes, MAX_NUMNODES); |
| |
| cpus_clear(span); |
| bitmap_zero(used_nodes, MAX_NUMNODES); |
| |
| nodemask = node_to_cpumask(node); |
| cpus_or(span, span, nodemask); |
| set_bit(node, used_nodes); |
| |
| for (i = 1; i < SD_NODES_PER_DOMAIN; i++) { |
| int next_node = find_next_best_node(node, used_nodes); |
| nodemask = node_to_cpumask(next_node); |
| cpus_or(span, span, nodemask); |
| } |
| |
| return span; |
| } |
| #endif |
| |
| /* |
| * At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we |
| * can switch it on easily if needed. |
| */ |
| #ifdef CONFIG_SCHED_SMT |
| static DEFINE_PER_CPU(struct sched_domain, cpu_domains); |
| static struct sched_group sched_group_cpus[NR_CPUS]; |
| static int cpu_to_cpu_group(int cpu) |
| { |
| return cpu; |
| } |
| #endif |
| |
| static DEFINE_PER_CPU(struct sched_domain, phys_domains); |
| static struct sched_group sched_group_phys[NR_CPUS]; |
| static int cpu_to_phys_group(int cpu) |
| { |
| #ifdef CONFIG_SCHED_SMT |
| return first_cpu(cpu_sibling_map[cpu]); |
| #else |
| return cpu; |
| #endif |
| } |
| |
| #ifdef CONFIG_NUMA |
| /* |
| * The init_sched_build_groups can't handle what we want to do with node |
| * groups, so roll our own. Now each node has its own list of groups which |
| * gets dynamically allocated. |
| */ |
| static DEFINE_PER_CPU(struct sched_domain, node_domains); |
| static struct sched_group **sched_group_nodes_bycpu[NR_CPUS]; |
| |
| static DEFINE_PER_CPU(struct sched_domain, allnodes_domains); |
| static struct sched_group *sched_group_allnodes_bycpu[NR_CPUS]; |
| |
| static int cpu_to_allnodes_group(int cpu) |
| { |
| return cpu_to_node(cpu); |
| } |
| #endif |
| |
| /* |
| * Build sched domains for a given set of cpus and attach the sched domains |
| * to the individual cpus |
| */ |
| void build_sched_domains(const cpumask_t *cpu_map) |
| { |
| int i; |
| #ifdef CONFIG_NUMA |
| struct sched_group **sched_group_nodes = NULL; |
| struct sched_group *sched_group_allnodes = NULL; |
| |
| /* |
| * Allocate the per-node list of sched groups |
| */ |
| sched_group_nodes = kmalloc(sizeof(struct sched_group*)*MAX_NUMNODES, |
| GFP_ATOMIC); |
| if (!sched_group_nodes) { |
| printk(KERN_WARNING "Can not alloc sched group node list\n"); |
| return; |
| } |
| sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes; |
| #endif |
| |
| /* |
| * Set up domains for cpus specified by the cpu_map. |
| */ |
| for_each_cpu_mask(i, *cpu_map) { |
| int group; |
| struct sched_domain *sd = NULL, *p; |
| cpumask_t nodemask = node_to_cpumask(cpu_to_node(i)); |
| |
| cpus_and(nodemask, nodemask, *cpu_map); |
| |
| #ifdef CONFIG_NUMA |
| if (cpus_weight(*cpu_map) |
| > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) { |
| if (!sched_group_allnodes) { |
| sched_group_allnodes |
| = kmalloc(sizeof(struct sched_group) |
| * MAX_NUMNODES, |
| GFP_KERNEL); |
| if (!sched_group_allnodes) { |
| printk(KERN_WARNING |
| "Can not alloc allnodes sched group\n"); |
| break; |
| } |
| sched_group_allnodes_bycpu[i] |
| = sched_group_allnodes; |
| } |
| sd = &per_cpu(allnodes_domains, i); |
| *sd = SD_ALLNODES_INIT; |
| sd->span = *cpu_map; |
| group = cpu_to_allnodes_group(i); |
| sd->groups = &sched_group_allnodes[group]; |
| p = sd; |
| } else |
| p = NULL; |
| |
| sd = &per_cpu(node_domains, i); |
| *sd = SD_NODE_INIT; |
| sd->span = sched_domain_node_span(cpu_to_node(i)); |
| sd->parent = p; |
| cpus_and(sd->span, sd->span, *cpu_map); |
| #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_map); |
| sd->parent = p; |
| sd->groups = &sched_group_cpus[group]; |
| #endif |
| } |
| |
| #ifdef CONFIG_SCHED_SMT |
| /* Set up CPU (sibling) groups */ |
| for_each_cpu_mask(i, *cpu_map) { |
| cpumask_t this_sibling_map = cpu_sibling_map[i]; |
| cpus_and(this_sibling_map, this_sibling_map, *cpu_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_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 */ |
| if (sched_group_allnodes) |
| init_sched_build_groups(sched_group_allnodes, *cpu_map, |
| &cpu_to_allnodes_group); |
| |
| for (i = 0; i < MAX_NUMNODES; i++) { |
| /* Set up node groups */ |
| struct sched_group *sg, *prev; |
| cpumask_t nodemask = node_to_cpumask(i); |
| cpumask_t domainspan; |
| cpumask_t covered = CPU_MASK_NONE; |
| int j; |
| |
| cpus_and(nodemask, nodemask, *cpu_map); |
| if (cpus_empty(nodemask)) { |
| sched_group_nodes[i] = NULL; |
| continue; |
| } |
| |
| domainspan = sched_domain_node_span(i); |
| cpus_and(domainspan, domainspan, *cpu_map); |
| |
| sg = kmalloc(sizeof(struct sched_group), GFP_KERNEL); |
| sched_group_nodes[i] = sg; |
| for_each_cpu_mask(j, nodemask) { |
| struct sched_domain *sd; |
| sd = &per_cpu(node_domains, j); |
| sd->groups = sg; |
| if (sd->groups == NULL) { |
| /* Turn off balancing if we have no groups */ |
| sd->flags = 0; |
| } |
| } |
| if (!sg) { |
| printk(KERN_WARNING |
| "Can not alloc domain group for node %d\n", i); |
| continue; |
| } |
| sg->cpu_power = 0; |
| sg->cpumask = nodemask; |
| cpus_or(covered, covered, nodemask); |
| prev = sg; |
| |
| for (j = 0; j < MAX_NUMNODES; j++) { |
| cpumask_t tmp, notcovered; |
| int n = (i + j) % MAX_NUMNODES; |
| |
| cpus_complement(notcovered, covered); |
| cpus_and(tmp, notcovered, *cpu_map); |
| cpus_and(tmp, tmp, domainspan); |
| if (cpus_empty(tmp)) |
| break; |
| |
| nodemask = node_to_cpumask(n); |
| cpus_and(tmp, tmp, nodemask); |
| if (cpus_empty(tmp)) |
| continue; |
| |
| sg = kmalloc(sizeof(struct sched_group), GFP_KERNEL); |
| if (!sg) { |
| printk(KERN_WARNING |
| "Can not alloc domain group for node %d\n", j); |
| break; |
| } |
| sg->cpu_power = 0; |
| sg->cpumask = tmp; |
| cpus_or(covered, covered, tmp); |
| prev->next = sg; |
| prev = sg; |
| } |
| prev->next = sched_group_nodes[i]; |
| } |
| #endif |
| |
| /* Calculate CPU power for physical packages and nodes */ |
| for_each_cpu_mask(i, *cpu_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 |
| sd = &per_cpu(allnodes_domains, i); |
| if (sd->groups) { |
| power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE * |
| (cpus_weight(sd->groups->cpumask)-1) / 10; |
| sd->groups->cpu_power = power; |
| } |
| #endif |
| } |
| |
| #ifdef CONFIG_NUMA |
| for (i = 0; i < MAX_NUMNODES; i++) { |
| struct sched_group *sg = sched_group_nodes[i]; |
| int j; |
| |
| if (sg == NULL) |
| continue; |
| next_sg: |
| for_each_cpu_mask(j, sg->cpumask) { |
| struct sched_domain *sd; |
| int power; |
| |
| sd = &per_cpu(phys_domains, j); |
| if (j != first_cpu(sd->groups->cpumask)) { |
| /* |
| * Only add "power" once for each |
| * physical package. |
| */ |
| continue; |
| } |
| power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE * |
| (cpus_weight(sd->groups->cpumask)-1) / 10; |
| |
| sg->cpu_power += power; |
| } |
| sg = sg->next; |
| if (sg != sched_group_nodes[i]) |
| goto next_sg; |
| } |
| #endif |
| |
| /* Attach the domains */ |
| for_each_cpu_mask(i, *cpu_map) { |
| 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); |
| } |
| /* |
| * Tune cache-hot values: |
| */ |
| calibrate_migration_costs(cpu_map); |
| } |
| /* |
| * Set up scheduler domains and groups. Callers must hold the hotplug lock. |
| */ |
| static void arch_init_sched_domains(const cpumask_t *cpu_map) |
| { |
| cpumask_t cpu_default_map; |
| |
| /* |
| * Setup mask for cpus without special case scheduling requirements. |
| * For now this just excludes isolated cpus, but could be used to |
| * exclude other special cases in the future. |
| */ |
| cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map); |
| |
| build_sched_domains(&cpu_default_map); |
| } |
| |
| static void arch_destroy_sched_domains(const cpumask_t *cpu_map) |
| { |
| #ifdef CONFIG_NUMA |
| int i; |
| int cpu; |
| |
| for_each_cpu_mask(cpu, *cpu_map) { |
| struct sched_group *sched_group_allnodes |
| = sched_group_allnodes_bycpu[cpu]; |
| struct sched_group **sched_group_nodes |
| = sched_group_nodes_bycpu[cpu]; |
| |
| if (sched_group_allnodes) { |
| kfree(sched_group_allnodes); |
| sched_group_allnodes_bycpu[cpu] = NULL; |
| } |
| |
| if (!sched_group_nodes) |
| continue; |
| |
| for (i = 0; i < MAX_NUMNODES; i++) { |
| cpumask_t nodemask = node_to_cpumask(i); |
| struct sched_group *oldsg, *sg = sched_group_nodes[i]; |
| |
| cpus_and(nodemask, nodemask, *cpu_map); |
| if (cpus_empty(nodemask)) |
| continue; |
| |
| if (sg == NULL) |
| continue; |
| sg = sg->next; |
| next_sg: |
| oldsg = sg; |
| sg = sg->next; |
| kfree(oldsg); |
| if (oldsg != sched_group_nodes[i]) |
| goto next_sg; |
| } |
| kfree(sched_group_nodes); |
| sched_group_nodes_bycpu[cpu] = NULL; |
| } |
| #endif |
| } |
| |
| /* |
| * Detach sched domains from a group of cpus specified in cpu_map |
| * These cpus will now be attached to the NULL domain |
| */ |
| static inline void detach_destroy_domains(const cpumask_t *cpu_map) |
| { |
| int i; |
| |
| for_each_cpu_mask(i, *cpu_map) |
| cpu_attach_domain(NULL, i); |
| synchronize_sched(); |
| arch_destroy_sched_domains(cpu_map); |
| } |
| |
| /* |
| * Partition sched domains as specified by the cpumasks below. |
| * This attaches all cpus from the cpumasks to the NULL domain, |
| * waits for a RCU quiescent period, recalculates sched |
| * domain information and then attaches them back to the |
| * correct sched domains |
| * Call with hotplug lock held |
| */ |
| void partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2) |
| { |
| cpumask_t change_map; |
| |
| cpus_and(*partition1, *partition1, cpu_online_map); |
| cpus_and(*partition2, *partition2, cpu_online_map); |
| cpus_or(change_map, *partition1, *partition2); |
| |
| /* Detach sched domains from all of the affected cpus */ |
| detach_destroy_domains(&change_map); |
| if (!cpus_empty(*partition1)) |
| build_sched_domains(partition1); |
| if (!cpus_empty(*partition2)) |
| build_sched_domains(partition2); |
| } |
| |
| #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 the NULL 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) |
| { |
| switch (action) { |
| case CPU_UP_PREPARE: |
| case CPU_DOWN_PREPARE: |
| detach_destroy_domains(&cpu_online_map); |
| 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(&cpu_online_map); |
| |
| return NOTIFY_OK; |
| } |
| #endif |
| |
| void __init sched_init_smp(void) |
| { |
| lock_cpu_hotplug(); |
| arch_init_sched_domains(&cpu_online_map); |
| 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->nr_running = 0; |
| rq->active = rq->arrays; |
| rq->expired = rq->arrays + 1; |
| rq->best_expired_prio = MAX_PRIO; |
| |
| #ifdef CONFIG_SMP |
| rq->sd = NULL; |
| for (j = 1; j < 3; j++) |
| rq->cpu_load[j] = 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 */ |
| |
| #ifdef CONFIG_IA64 |
| /* |
| * These functions are only useful for the IA64 MCA handling. |
| * |
| * They can only be called when the whole system has been |
| * stopped - every CPU needs to be quiescent, and no scheduling |
| * activity can take place. Using them for anything else would |
| * be a serious bug, and as a result, they aren't even visible |
| * under any other configuration. |
| */ |
| |
| /** |
| * curr_task - return the current task for a given cpu. |
| * @cpu: the processor in question. |
| * |
| * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! |
| */ |
| task_t *curr_task(int cpu) |
| { |
| return cpu_curr(cpu); |
| } |
| |
| /** |
| * set_curr_task - set the current task for a given cpu. |
| * @cpu: the processor in question. |
| * @p: the task pointer to set. |
| * |
| * Description: This function must only be used when non-maskable interrupts |
| * are serviced on a separate stack. It allows the architecture to switch the |
| * notion of the current task on a cpu in a non-blocking manner. This function |
| * must be called with all CPU's synchronized, and interrupts disabled, the |
| * and caller must save the original value of the current task (see |
| * curr_task() above) and restore that value before reenabling interrupts and |
| * re-starting the system. |
| * |
| * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! |
| */ |
| void set_curr_task(int cpu, task_t *p) |
| { |
| cpu_curr(cpu) = p; |
| } |
| |
| #endif |