stats.h

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#ifdef CONFIG_SCHEDSTATS

/*
 * 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;
}

/*
 * 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);
}

/*
 * 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.
 */

static inline void account_group_user_time(struct task_struct *tsk,
                       cputime_t cputime)
{
    struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

    if (!cputimer->running)
        return;

    raw_spin_lock(&cputimer->lock);
    cputimer->cputime.utime += cputime;
    raw_spin_unlock(&cputimer->lock);
}

static inline void account_group_system_time(struct task_struct *tsk,
                         cputime_t cputime)
{
    struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

    if (!cputimer->running)
        return;

    raw_spin_lock(&cputimer->lock);
    cputimer->cputime.stime += cputime;
    raw_spin_unlock(&cputimer->lock);
}

static inline void account_group_exec_runtime(struct task_struct *tsk,
                          unsigned long long ns)
{
    struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

    if (!cputimer->running)
        return;

    raw_spin_lock(&cputimer->lock);
    cputimer->cputime.sum_exec_runtime += ns;
    raw_spin_unlock(&cputimer->lock);
}