sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks
Remove the direct {push,pull} balancing operations from switched_{from,to}_rt() / prio_changed_rt() and use the balance callback queue. Again, err on the side of too many reschedules; since too few is a hard bug while too many is just annoying. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: ktkhai@parallels.com Cc: rostedt@goodmis.org Cc: juri.lelli@gmail.com Cc: pang.xunlei@linaro.org Cc: oleg@redhat.com Cc: wanpeng.li@linux.intel.com Cc: umgwanakikbuti@gmail.com Link: http://lkml.kernel.org/r/20150611124742.766832367@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -354,16 +354,23 @@ static inline int has_pushable_tasks(struct rq *rq)
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return !plist_head_empty(&rq->rt.pushable_tasks);
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}
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static DEFINE_PER_CPU(struct callback_head, rt_balance_head);
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static DEFINE_PER_CPU(struct callback_head, rt_push_head);
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static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
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static void push_rt_tasks(struct rq *);
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static void pull_rt_task(struct rq *);
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static inline void queue_push_tasks(struct rq *rq)
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{
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if (!has_pushable_tasks(rq))
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return;
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queue_balance_callback(rq, &per_cpu(rt_balance_head, rq->cpu), push_rt_tasks);
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queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
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}
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static inline void queue_pull_task(struct rq *rq)
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{
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queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
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}
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static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
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@ -2139,7 +2146,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
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if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
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return;
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pull_rt_task(rq);
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queue_pull_task(rq);
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}
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void __init init_sched_rt_class(void)
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@ -2160,8 +2167,6 @@ void __init init_sched_rt_class(void)
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*/
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static void switched_to_rt(struct rq *rq, struct task_struct *p)
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{
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int check_resched = 1;
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/*
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* If we are already running, then there's nothing
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* that needs to be done. But if we are not running
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@ -2171,13 +2176,12 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
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*/
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if (task_on_rq_queued(p) && rq->curr != p) {
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#ifdef CONFIG_SMP
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if (p->nr_cpus_allowed > 1 && rq->rt.overloaded &&
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/* Don't resched if we changed runqueues */
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push_rt_task(rq) && rq != task_rq(p))
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check_resched = 0;
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#endif /* CONFIG_SMP */
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if (check_resched && p->prio < rq->curr->prio)
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if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
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queue_push_tasks(rq);
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#else
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if (p->prio < rq->curr->prio)
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resched_curr(rq);
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#endif /* CONFIG_SMP */
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}
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}
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@ -2198,14 +2202,13 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
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* may need to pull tasks to this runqueue.
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*/
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if (oldprio < p->prio)
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pull_rt_task(rq);
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queue_pull_task(rq);
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/*
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* If there's a higher priority task waiting to run
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* then reschedule. Note, the above pull_rt_task
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* can release the rq lock and p could migrate.
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* Only reschedule if p is still on the same runqueue.
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* then reschedule.
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*/
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if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
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if (p->prio > rq->rt.highest_prio.curr)
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resched_curr(rq);
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#else
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/* For UP simply resched on drop of prio */
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