#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 15

static int show_schedstat(struct seq_file *seq, void *v)
{
        int cpu;
        int mask_len = DIV_ROUND_UP(NR_CPUS, 32) * 9;
        char *mask_str = kmalloc(mask_len, GFP_KERNEL);

        if (mask_str == NULL)
                return -ENOMEM;

        seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
        seq_printf(seq, "timestamp %lu\n", jiffies);
        for_each_online_cpu(cpu) {
                struct rq *rq = cpu_rq(cpu);
#ifdef CONFIG_SMP
                struct sched_domain *sd;
                int dcount = 0;
#endif

                /* runqueue-specific stats */
                seq_printf(seq,
                    "cpu%d %u %u %u %u %u %u %llu %llu %lu",
                    cpu, rq->yld_count,
                    rq->sched_switch, rq->sched_count, rq->sched_goidle,
                    rq->ttwu_count, rq->ttwu_local,
                    rq->rq_cpu_time,
                    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);

                seq_printf(seq, "\n");

#ifdef CONFIG_SMP
                /* domain-specific stats */
                preempt_disable();
                for_each_domain(cpu, sd) {
                        enum cpu_idle_type itype;

                        cpumask_scnprintf(mask_str, mask_len,
                                          sched_domain_span(sd));
                        seq_printf(seq, "domain%d %s", dcount++, mask_str);
                        for (itype = CPU_IDLE; itype < CPU_MAX_IDLE_TYPES;
                                        itype++) {
                                seq_printf(seq, " %u %u %u %u %u %u %u %u",
                                    sd->lb_count[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,
                                   " %u %u %u %u %u %u %u %u %u %u %u %u\n",
                            sd->alb_count, sd->alb_failed, sd->alb_pushed,
                            sd->sbe_count, sd->sbe_balanced, sd->sbe_pushed,
                            sd->sbf_count, sd->sbf_balanced, sd->sbf_pushed,
                            sd->ttwu_wake_remote, sd->ttwu_move_affine,
                            sd->ttwu_move_balance);
                }
                preempt_enable();
#endif
        }
        kfree(mask_str);
        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;
}

static const struct file_operations proc_schedstat_operations = {
        .open    = schedstat_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = single_release,
};

static int __init proc_schedstat_init(void)
{
        proc_create("schedstat", 0, NULL, &proc_schedstat_operations);
        return 0;
}
module_init(proc_schedstat_init);

/*
 * Expects runqueue lock to be held for atomicity of update
 */
static inline void
rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
{
        if (rq) {
                rq->rq_sched_info.run_delay += delta;
                rq->rq_sched_info.pcount++;
        }
}

/*
 * Expects runqueue lock to be held for atomicity of update
 */
static inline void
rq_sched_info_depart(struct rq *rq, unsigned long long delta)
{
        if (rq)
                rq->rq_cpu_time += delta;
}

static inline void
rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
{
        if (rq)
                rq->rq_sched_info.run_delay += delta;
}
# define schedstat_inc(rq, field)       do { (rq)->field++; } while (0)
# define schedstat_add(rq, field, amt)  do { (rq)->field += (amt); } while (0)
# define schedstat_set(var, val)        do { var = (val); } while (0)
#else /* !CONFIG_SCHEDSTATS */
static inline void
rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
{}
static inline void
rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
{}
static inline void
rq_sched_info_depart(struct rq *rq, unsigned long long delta)
{}
# define schedstat_inc(rq, field)       do { } while (0)
# define schedstat_add(rq, field, amt)  do { } while (0)
# define schedstat_set(var, val)        do { } while (0)
#endif

#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
static inline void sched_info_reset_dequeued(struct task_struct *t)
{
        t->sched_info.last_queued = 0;
}

/*
 * 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()).
 *
 * Though we are interested in knowing how long it was from the *first* time a
 * task was queued to the time that it finally hit a cpu, we call this routine
 * from dequeue_task() to account for possible rq->clock skew across cpus. The
 * delta taken on each cpu would annul the skew.
 */
static inline void sched_info_dequeued(struct task_struct *t)
{
        unsigned long long now = task_rq(t)->clock, delta = 0;

        if (unlikely(sched_info_on()))
                if (t->sched_info.last_queued)
                        delta = now - t->sched_info.last_queued;
        sched_info_reset_dequeued(t);
        t->sched_info.run_delay += delta;

        rq_sched_info_dequeued(task_rq(t), delta);
}

/*
 * 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 void sched_info_arrive(struct task_struct *t)
{
        unsigned long long now = task_rq(t)->clock, delta = 0;

        if (t->sched_info.last_queued)
                delta = now - t->sched_info.last_queued;
        sched_info_reset_dequeued(t);
        t->sched_info.run_delay += delta;
        t->sched_info.last_arrival = now;
        t->sched_info.pcount++;

        rq_sched_info_arrive(task_rq(t), delta);
}

/*
 * 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(struct task_struct *t)
{
        if (unlikely(sched_info_on()))
                if (!t->sched_info.last_queued)
                        t->sched_info.last_queued = task_rq(t)->clock;
}

/*
 * Called when a process ceases being the active-running process, either
 * voluntarily or involuntarily.  Now we can calculate how long we ran.
 * Also, if the process is still in the TASK_RUNNING state, call
 * sched_info_queued() to mark that it has now again started waiting on
 * the runqueue.
 */
static inline void sched_info_depart(struct task_struct *t)
{
        unsigned long long delta = task_rq(t)->clock -
                                        t->sched_info.last_arrival;

        rq_sched_info_depart(task_rq(t), delta);

        if (t->state == TASK_RUNNING)
                sched_info_queued(t);
}

/*
 * 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(struct task_struct *prev, struct task_struct *next)
{
        struct rq *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);
}
static inline void
sched_info_switch(struct task_struct *prev, struct task_struct *next)
{
        if (unlikely(sched_info_on()))
                __sched_info_switch(prev, next);
}
#else
#define sched_info_queued(t)                    do { } while (0)
#define sched_info_reset_dequeued(t)    do { } while (0)
#define sched_info_dequeued(t)                  do { } while (0)
#define sched_info_switch(t, next)              do { } while (0)
#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */

/*
 * The following are functions that support scheduler-internal time accounting.
 * These functions are generally called at the timer tick.  None of this depends
 * on CONFIG_SCHEDSTATS.
 */

/**
 * account_group_user_time - Maintain utime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @cputime:    Time value by which to increment the utime field of the
 *              thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the utime field there.
 */
static inline void account_group_user_time(struct task_struct *tsk,
                                           cputime_t cputime)
{
        struct thread_group_cputimer *cputimer;

        /* tsk == current, ensure it is safe to use ->signal */
        if (unlikely(tsk->exit_state))
                return;

        cputimer = &tsk->signal->cputimer;

        if (!cputimer->running)
                return;

        spin_lock(&cputimer->lock);
        cputimer->cputime.utime =
                cputime_add(cputimer->cputime.utime, cputime);
        spin_unlock(&cputimer->lock);
}

/**
 * account_group_system_time - Maintain stime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @cputime:    Time value by which to increment the stime field of the
 *              thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the stime field there.
 */
static inline void account_group_system_time(struct task_struct *tsk,
                                             cputime_t cputime)
{
        struct thread_group_cputimer *cputimer;

        /* tsk == current, ensure it is safe to use ->signal */
        if (unlikely(tsk->exit_state))
                return;

        cputimer = &tsk->signal->cputimer;

        if (!cputimer->running)
                return;

        spin_lock(&cputimer->lock);
        cputimer->cputime.stime =
                cputime_add(cputimer->cputime.stime, cputime);
        spin_unlock(&cputimer->lock);
}

/**
 * account_group_exec_runtime - Maintain exec runtime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @ns:         Time value by which to increment the sum_exec_runtime field
 *              of the thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the sum_exec_runtime field there.
 */
static inline void account_group_exec_runtime(struct task_struct *tsk,
                                              unsigned long long ns)
{
        struct thread_group_cputimer *cputimer;
        struct signal_struct *sig;

        sig = tsk->signal;
        /* see __exit_signal()->task_rq_unlock_wait() */
        barrier();
        if (unlikely(!sig))
                return;

        cputimer = &sig->cputimer;

        if (!cputimer->running)
                return;

        spin_lock(&cputimer->lock);
        cputimer->cputime.sum_exec_runtime += ns;
        spin_unlock(&cputimer->lock);
}