forked from Minki/linux
da7a735e51
When a task is taken out of the fair class we must ensure the vruntime
is properly normalized because when we put it back in it will assume
to be normalized.
The case that goes wrong is when changing away from the fair class
while sleeping. Sleeping tasks have non-normalized vruntime in order
to make sleeper-fairness work. So treat the switch away from fair as a
wakeup and preserve the relative vruntime.
Also update sysrq-n to call the ->switch_{to,from} methods.
Reported-by: Onkalo Samu <samu.p.onkalo@nokia.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
100 lines
2.1 KiB
C
100 lines
2.1 KiB
C
/*
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* idle-task scheduling class.
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*
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* (NOTE: these are not related to SCHED_IDLE tasks which are
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* handled in sched_fair.c)
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*/
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#ifdef CONFIG_SMP
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static int
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select_task_rq_idle(struct rq *rq, struct task_struct *p, int sd_flag, int flags)
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{
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return task_cpu(p); /* IDLE tasks as never migrated */
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}
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#endif /* CONFIG_SMP */
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/*
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* Idle tasks are unconditionally rescheduled:
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*/
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static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
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{
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resched_task(rq->idle);
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}
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static struct task_struct *pick_next_task_idle(struct rq *rq)
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{
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schedstat_inc(rq, sched_goidle);
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calc_load_account_idle(rq);
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return rq->idle;
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}
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/*
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* It is not legal to sleep in the idle task - print a warning
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* message if some code attempts to do it:
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*/
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static void
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dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
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{
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raw_spin_unlock_irq(&rq->lock);
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printk(KERN_ERR "bad: scheduling from the idle thread!\n");
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dump_stack();
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raw_spin_lock_irq(&rq->lock);
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}
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static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
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{
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}
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static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
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{
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}
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static void set_curr_task_idle(struct rq *rq)
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{
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}
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static void switched_to_idle(struct rq *rq, struct task_struct *p)
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{
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BUG();
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}
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static void
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prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
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{
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BUG();
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}
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static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
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{
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return 0;
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}
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/*
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* Simple, special scheduling class for the per-CPU idle tasks:
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*/
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static const struct sched_class idle_sched_class = {
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/* .next is NULL */
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/* no enqueue/yield_task for idle tasks */
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/* dequeue is not valid, we print a debug message there: */
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.dequeue_task = dequeue_task_idle,
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.check_preempt_curr = check_preempt_curr_idle,
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.pick_next_task = pick_next_task_idle,
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.put_prev_task = put_prev_task_idle,
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#ifdef CONFIG_SMP
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.select_task_rq = select_task_rq_idle,
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#endif
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.set_curr_task = set_curr_task_idle,
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.task_tick = task_tick_idle,
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.get_rr_interval = get_rr_interval_idle,
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.prio_changed = prio_changed_idle,
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.switched_to = switched_to_idle,
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/* no .task_new for idle tasks */
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};
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