From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit e3fca9e7cbfb72694a21c886fcdf9f059cfded9c upstream. Generalize the post_schedule() stuff into a balance callback list. This allows us to more easily use it outside of schedule() and cross sched_class. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: ktkhai@xxxxxxxxxxxxx Cc: rostedt@xxxxxxxxxxx Cc: juri.lelli@xxxxxxxxx Cc: pang.xunlei@xxxxxxxxxx Cc: oleg@xxxxxxxxxx Cc: wanpeng.li@xxxxxxxxxxxxxxx Cc: umgwanakikbuti@xxxxxxxxx Link: http://lkml.kernel.org/r/20150611124742.424032725@xxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- kernel/sched/core.c | 36 ++++++++++++++++++++++++------------ kernel/sched/rt.c | 27 ++++++++++++++++----------- kernel/sched/sched.h | 19 +++++++++++++++++-- 3 files changed, 57 insertions(+), 25 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0bcdceaca6e2..7bf52708993e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1911,18 +1911,30 @@ static inline void pre_schedule(struct rq *rq, struct task_struct *prev) } /* rq->lock is NOT held, but preemption is disabled */ -static inline void post_schedule(struct rq *rq) +static void __balance_callback(struct rq *rq) { - if (rq->post_schedule) { - unsigned long flags; + struct callback_head *head, *next; + void (*func)(struct rq *rq); + unsigned long flags; - raw_spin_lock_irqsave(&rq->lock, flags); - if (rq->curr->sched_class->post_schedule) - rq->curr->sched_class->post_schedule(rq); - raw_spin_unlock_irqrestore(&rq->lock, flags); + raw_spin_lock_irqsave(&rq->lock, flags); + head = rq->balance_callback; + rq->balance_callback = NULL; + while (head) { + func = (void (*)(struct rq *))head->func; + next = head->next; + head->next = NULL; + head = next; - rq->post_schedule = 0; + func(rq); } + raw_spin_unlock_irqrestore(&rq->lock, flags); +} + +static inline void balance_callback(struct rq *rq) +{ + if (unlikely(rq->balance_callback)) + __balance_callback(rq); } #else @@ -1931,7 +1943,7 @@ static inline void pre_schedule(struct rq *rq, struct task_struct *p) { } -static inline void post_schedule(struct rq *rq) +static inline void balance_callback(struct rq *rq) { } @@ -1952,7 +1964,7 @@ asmlinkage void schedule_tail(struct task_struct *prev) * FIXME: do we need to worry about rq being invalidated by the * task_switch? */ - post_schedule(rq); + balance_callback(rq); #ifdef __ARCH_WANT_UNLOCKED_CTXSW /* In this case, finish_task_switch does not reenable preemption */ @@ -2449,7 +2461,7 @@ need_resched: } else raw_spin_unlock_irq(&rq->lock); - post_schedule(rq); + balance_callback(rq); sched_preempt_enable_no_resched(); if (need_resched()) @@ -6516,7 +6528,7 @@ void __init sched_init(void) rq->sd = NULL; rq->rd = NULL; rq->cpu_power = SCHED_POWER_SCALE; - rq->post_schedule = 0; + rq->balance_callback = NULL; rq->active_balance = 0; rq->next_balance = jiffies; rq->push_cpu = 0; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index e849d4070c7f..25f6d7ae589d 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -315,6 +315,18 @@ static inline int has_pushable_tasks(struct rq *rq) return !plist_head_empty(&rq->rt.pushable_tasks); } +static DEFINE_PER_CPU(struct callback_head, rt_balance_head); + +static void push_rt_tasks(struct rq *); + +static inline void queue_push_tasks(struct rq *rq) +{ + if (!has_pushable_tasks(rq)) + return; + + queue_balance_callback(rq, &per_cpu(rt_balance_head, rq->cpu), push_rt_tasks); +} + static void enqueue_pushable_task(struct rq *rq, struct task_struct *p) { plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks); @@ -359,6 +371,9 @@ void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) { } +static inline void queue_push_tasks(struct rq *rq) +{ +} #endif /* CONFIG_SMP */ static inline int on_rt_rq(struct sched_rt_entity *rt_se) @@ -1344,11 +1359,7 @@ static struct task_struct *pick_next_task_rt(struct rq *rq) dequeue_pushable_task(rq, p); #ifdef CONFIG_SMP - /* - * We detect this state here so that we can avoid taking the RQ - * lock again later if there is no need to push - */ - rq->post_schedule = has_pushable_tasks(rq); + queue_push_tasks(rq); #endif return p; @@ -1726,11 +1737,6 @@ static void pre_schedule_rt(struct rq *rq, struct task_struct *prev) pull_rt_task(rq); } -static void post_schedule_rt(struct rq *rq) -{ - push_rt_tasks(rq); -} - /* * If we are not running and we are not going to reschedule soon, we should * try to push tasks away now @@ -2003,7 +2009,6 @@ const struct sched_class rt_sched_class = { .rq_online = rq_online_rt, .rq_offline = rq_offline_rt, .pre_schedule = pre_schedule_rt, - .post_schedule = post_schedule_rt, .task_woken = task_woken_rt, .switched_from = switched_from_rt, #endif diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1a1cdc3783ed..e09e3e0466f7 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -460,9 +460,10 @@ struct rq { unsigned long cpu_power; + struct callback_head *balance_callback; + unsigned char idle_balance; /* For active balancing */ - int post_schedule; int active_balance; int push_cpu; struct cpu_stop_work active_balance_work; @@ -554,6 +555,21 @@ static inline u64 rq_clock_task(struct rq *rq) #ifdef CONFIG_SMP +static inline void +queue_balance_callback(struct rq *rq, + struct callback_head *head, + void (*func)(struct rq *rq)) +{ + lockdep_assert_held(&rq->lock); + + if (unlikely(head->next)) + return; + + head->func = (void (*)(struct callback_head *))func; + head->next = rq->balance_callback; + rq->balance_callback = head; +} + #define rcu_dereference_check_sched_domain(p) \ rcu_dereference_check((p), \ lockdep_is_held(&sched_domains_mutex)) @@ -981,7 +997,6 @@ struct sched_class { void (*migrate_task_rq)(struct task_struct *p, int next_cpu); void (*pre_schedule) (struct rq *this_rq, struct task_struct *task); - void (*post_schedule) (struct rq *this_rq); void (*task_waking) (struct task_struct *task); void (*task_woken) (struct rq *this_rq, struct task_struct *task); -- 2.7.2 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html