e7693a362e
The current wake-up code path tries to determine if it can optimize the wake-up to "this_cpu" by computing load calculations. The problem is that these calculations are only relevant to SCHED_OTHER tasks where load is king. For RT tasks, priority is king. So the load calculation is completely wasted bandwidth. Therefore, we create a new sched_class interface to help with pre-wakeup routing decisions and move the load calculation as a function of CFS task's class. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
99 lines
2.2 KiB
C
99 lines
2.2 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 select_task_rq_idle(struct task_struct *p, int sync)
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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)
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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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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 sleep)
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{
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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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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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#ifdef CONFIG_SMP
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static unsigned long
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load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
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unsigned long max_load_move,
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struct sched_domain *sd, enum cpu_idle_type idle,
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int *all_pinned, int *this_best_prio)
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{
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return 0;
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}
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static int
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move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
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struct sched_domain *sd, enum cpu_idle_type idle)
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{
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return 0;
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}
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#endif
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static void task_tick_idle(struct rq *rq, struct task_struct *curr)
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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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/*
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* Simple, special scheduling class for the per-CPU idle tasks:
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*/
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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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#ifdef CONFIG_SMP
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.select_task_rq = select_task_rq_idle,
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#endif /* CONFIG_SMP */
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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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.load_balance = load_balance_idle,
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.move_one_task = move_one_task_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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/* no .task_new for idle tasks */
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};
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