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#include "sched.h"
/*
* stop-task scheduling class.
*
* The stop task is the highest priority task in the system, it preempts
* everything and will be preempted by nothing.
*
* See kernel/stop_machine.c
*/
#ifdef CONFIG_SMP
static int
select_task_rq_stop(struct task_struct *p, int cpu, int sd_flag, int flags)
{
return task_cpu(p); /* stop tasks as never migrate */
}
#endif /* CONFIG_SMP */
#ifdef CONFIG_SCHED_HMP
static void
inc_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p)
{
inc_cumulative_runnable_avg(&rq->hmp_stats, p);
}
static void
dec_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p)
{
dec_cumulative_runnable_avg(&rq->hmp_stats, p);
}
static void
fixup_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p,
u32 new_task_load, u32 new_pred_demand)
{
s64 task_load_delta = (s64)new_task_load - task_load(p);
s64 pred_demand_delta = PRED_DEMAND_DELTA;
fixup_cumulative_runnable_avg(&rq->hmp_stats, p, task_load_delta,
pred_demand_delta);
}
#else /* CONFIG_SCHED_HMP */
static inline void
inc_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p) { }
static inline void
dec_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p) { }
#endif /* CONFIG_SCHED_HMP */
static void
check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags)
{
/* we're never preempted */
}
static struct task_struct *
pick_next_task_stop(struct rq *rq, struct task_struct *prev)
{
struct task_struct *stop = rq->stop;
if (!stop || !task_on_rq_queued(stop))
return NULL;
put_prev_task(rq, prev);
stop->se.exec_start = rq_clock_task(rq);
return stop;
}
static void
enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
{
add_nr_running(rq, 1);
inc_hmp_sched_stats_stop(rq, p);
}
static void
dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
{
sub_nr_running(rq, 1);
dec_hmp_sched_stats_stop(rq, p);
}
static void yield_task_stop(struct rq *rq)
{
BUG(); /* the stop task should never yield, its pointless. */
}
static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
{
struct task_struct *curr = rq->curr;
u64 delta_exec;
delta_exec = rq_clock_task(rq) - curr->se.exec_start;
if (unlikely((s64)delta_exec < 0))
delta_exec = 0;
schedstat_set(curr->se.statistics.exec_max,
max(curr->se.statistics.exec_max, delta_exec));
curr->se.sum_exec_runtime += delta_exec;
account_group_exec_runtime(curr, delta_exec);
curr->se.exec_start = rq_clock_task(rq);
cpuacct_charge(curr, delta_exec);
}
static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
{
}
static void set_curr_task_stop(struct rq *rq)
{
struct task_struct *stop = rq->stop;
stop->se.exec_start = rq_clock_task(rq);
}
static void switched_to_stop(struct rq *rq, struct task_struct *p)
{
BUG(); /* its impossible to change to this class */
}
static void
prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio)
{
BUG(); /* how!?, what priority? */
}
static unsigned int
get_rr_interval_stop(struct rq *rq, struct task_struct *task)
{
return 0;
}
static void update_curr_stop(struct rq *rq)
{
}
/*
* Simple, special scheduling class for the per-CPU stop tasks:
*/
const struct sched_class stop_sched_class = {
.next = &dl_sched_class,
.enqueue_task = enqueue_task_stop,
.dequeue_task = dequeue_task_stop,
.yield_task = yield_task_stop,
.check_preempt_curr = check_preempt_curr_stop,
.pick_next_task = pick_next_task_stop,
.put_prev_task = put_prev_task_stop,
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_stop,
.set_cpus_allowed = set_cpus_allowed_common,
#endif
.set_curr_task = set_curr_task_stop,
.task_tick = task_tick_stop,
.get_rr_interval = get_rr_interval_stop,
.prio_changed = prio_changed_stop,
.switched_to = switched_to_stop,
.update_curr = update_curr_stop,
#ifdef CONFIG_SCHED_HMP
.inc_hmp_sched_stats = inc_hmp_sched_stats_stop,
.dec_hmp_sched_stats = dec_hmp_sched_stats_stop,
.fixup_hmp_sched_stats = fixup_hmp_sched_stats_stop,
#endif
};
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