forked from luck/tmp_suning_uos_patched
sched: rt-group: deal with PI
Steven mentioned the fun case where a lock holding task will be throttled. Simple fix: allow groups that have boosted tasks to run anyway. If a runnable task in a throttled group gets boosted the dequeue/enqueue done by rt_mutex_setprio() is enough to unthrottle the group. This is ofcourse not quite correct. Two possible ways forward are: - second prio array for boosted tasks - boost to a prio ceiling (this would also work for deadline scheduling) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -362,6 +362,8 @@ struct rt_rq {
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u64 rt_time;
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#ifdef CONFIG_FAIR_GROUP_SCHED
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unsigned long rt_nr_boosted;
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struct rq *rq;
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struct list_head leaf_rt_rq_list;
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struct task_group *tg;
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@ -7112,6 +7114,7 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
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rt_rq->rt_throttled = 0;
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#ifdef CONFIG_FAIR_GROUP_SCHED
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rt_rq->rt_nr_boosted = 0;
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rt_rq->rq = rq;
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#endif
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}
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@ -110,6 +110,23 @@ static void sched_rt_ratio_dequeue(struct rt_rq *rt_rq)
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dequeue_rt_entity(rt_se);
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}
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static inline int rt_rq_throttled(struct rt_rq *rt_rq)
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{
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return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
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}
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static int rt_se_boosted(struct sched_rt_entity *rt_se)
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{
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struct rt_rq *rt_rq = group_rt_rq(rt_se);
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struct task_struct *p;
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if (rt_rq)
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return !!rt_rq->rt_nr_boosted;
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p = rt_task_of(rt_se);
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return p->prio != p->normal_prio;
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}
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#else
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static inline unsigned int sched_rt_ratio(struct rt_rq *rt_rq)
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@ -149,6 +166,10 @@ static inline void sched_rt_ratio_dequeue(struct rt_rq *rt_rq)
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{
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}
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static inline int rt_rq_throttled(struct rt_rq *rt_rq)
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{
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return rt_rq->rt_throttled;
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}
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#endif
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static inline int rt_se_prio(struct sched_rt_entity *rt_se)
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@ -172,7 +193,7 @@ static int sched_rt_ratio_exceeded(struct rt_rq *rt_rq)
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return 0;
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if (rt_rq->rt_throttled)
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return 1;
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return rt_rq_throttled(rt_rq);
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period = (u64)sysctl_sched_rt_period * NSEC_PER_MSEC;
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ratio = (period * rt_ratio) >> SCHED_RT_FRAC_SHIFT;
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@ -183,8 +204,10 @@ static int sched_rt_ratio_exceeded(struct rt_rq *rt_rq)
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rq->rt_throttled = 1;
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rt_rq->rt_throttled = 1;
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sched_rt_ratio_dequeue(rt_rq);
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return 1;
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if (rt_rq_throttled(rt_rq)) {
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sched_rt_ratio_dequeue(rt_rq);
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return 1;
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}
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}
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return 0;
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@ -265,6 +288,10 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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update_rt_migration(rq_of_rt_rq(rt_rq));
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#endif
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#ifdef CONFIG_FAIR_GROUP_SCHED
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if (rt_se_boosted(rt_se))
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rt_rq->rt_nr_boosted++;
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#endif
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}
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static inline
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@ -295,6 +322,12 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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update_rt_migration(rq_of_rt_rq(rt_rq));
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#endif /* CONFIG_SMP */
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#ifdef CONFIG_FAIR_GROUP_SCHED
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if (rt_se_boosted(rt_se))
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rt_rq->rt_nr_boosted--;
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WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
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#endif
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}
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static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
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@ -303,7 +336,7 @@ static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
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struct rt_prio_array *array = &rt_rq->active;
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struct rt_rq *group_rq = group_rt_rq(rt_se);
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if (group_rq && group_rq->rt_throttled)
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if (group_rq && rt_rq_throttled(group_rq))
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return;
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list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
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@ -496,7 +529,7 @@ static struct task_struct *pick_next_task_rt(struct rq *rq)
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if (unlikely(!rt_rq->rt_nr_running))
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return NULL;
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if (sched_rt_ratio_exceeded(rt_rq))
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if (rt_rq_throttled(rt_rq))
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return NULL;
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do {
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