From e3fca9e7cbfb72694a21c886fcdf9f059cfded9c Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 11 Jun 2015 14:46:37 +0200 Subject: [PATCH] sched: Replace post_schedule with a balance callback list 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) 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/20150611124742.424032725@infradead.org Signed-off-by: Thomas Gleixner --- kernel/sched/core.c | 36 ++++++++++++++++++++++++------------ kernel/sched/deadline.c | 21 +++++++++++---------- kernel/sched/rt.c | 25 +++++++++++-------------- kernel/sched/sched.h | 19 +++++++++++++++++-- 4 files changed, 63 insertions(+), 38 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 41942a5f3315..fa32bc09dadf 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2277,23 +2277,35 @@ static struct rq *finish_task_switch(struct task_struct *prev) #ifdef CONFIG_SMP /* 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 -static inline void post_schedule(struct rq *rq) +static inline void balance_callback(struct rq *rq) { } @@ -2311,7 +2323,7 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev) /* finish_task_switch() drops rq->lock and enables preemtion */ preempt_disable(); rq = finish_task_switch(prev); - post_schedule(rq); + balance_callback(rq); preempt_enable(); if (current->set_child_tid) @@ -2823,7 +2835,7 @@ static void __sched __schedule(void) } else raw_spin_unlock_irq(&rq->lock); - post_schedule(rq); + balance_callback(rq); } static inline void sched_submit_work(struct task_struct *tsk) @@ -7219,7 +7231,7 @@ void __init sched_init(void) rq->sd = NULL; rq->rd = NULL; rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_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/deadline.c b/kernel/sched/deadline.c index 7a08d590990e..d80523fb1de5 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -213,9 +213,16 @@ static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) return dl_task(prev); } -static inline void set_post_schedule(struct rq *rq) +static DEFINE_PER_CPU(struct callback_head, dl_balance_head); + +static void push_dl_tasks(struct rq *); + +static inline void queue_push_tasks(struct rq *rq) { - rq->post_schedule = has_pushable_dl_tasks(rq); + if (!has_pushable_dl_tasks(rq)) + return; + + queue_balance_callback(rq, &per_cpu(dl_balance_head, rq->cpu), push_dl_tasks); } static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq); @@ -296,7 +303,7 @@ static inline int pull_dl_task(struct rq *rq) return 0; } -static inline void set_post_schedule(struct rq *rq) +static inline void queue_push_tasks(struct rq *rq) { } #endif /* CONFIG_SMP */ @@ -1126,7 +1133,7 @@ struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev) if (hrtick_enabled(rq)) start_hrtick_dl(rq, p); - set_post_schedule(rq); + queue_push_tasks(rq); return p; } @@ -1544,11 +1551,6 @@ skip: return ret; } -static void post_schedule_dl(struct rq *rq) -{ - push_dl_tasks(rq); -} - /* * Since the task is not running and a reschedule is not going to happen * anytime soon on its runqueue, we try pushing it away now. @@ -1784,7 +1786,6 @@ const struct sched_class dl_sched_class = { .set_cpus_allowed = set_cpus_allowed_dl, .rq_online = rq_online_dl, .rq_offline = rq_offline_dl, - .post_schedule = post_schedule_dl, .task_woken = task_woken_dl, #endif diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 7d7093c51f8d..4f3726fe1246 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -354,13 +354,16 @@ static inline int has_pushable_tasks(struct rq *rq) return !plist_head_empty(&rq->rt.pushable_tasks); } -static inline void set_post_schedule(struct rq *rq) +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) { - /* - * 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); + 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) @@ -417,7 +420,7 @@ static inline int pull_rt_task(struct rq *this_rq) return 0; } -static inline void set_post_schedule(struct rq *rq) +static inline void queue_push_tasks(struct rq *rq) { } #endif /* CONFIG_SMP */ @@ -1497,7 +1500,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev) /* The running task is never eligible for pushing */ dequeue_pushable_task(rq, p); - set_post_schedule(rq); + queue_push_tasks(rq); return p; } @@ -2042,11 +2045,6 @@ skip: return ret; } -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 @@ -2318,7 +2316,6 @@ const struct sched_class rt_sched_class = { .set_cpus_allowed = set_cpus_allowed_rt, .rq_online = rq_online_rt, .rq_offline = rq_offline_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 f10a445910c9..62949ab06bc2 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -624,9 +624,10 @@ struct rq { unsigned long cpu_capacity; unsigned long cpu_capacity_orig; + 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; @@ -767,6 +768,21 @@ extern int migrate_swap(struct task_struct *, struct task_struct *); #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; +} + extern void sched_ttwu_pending(void); #define rcu_dereference_check_sched_domain(p) \ @@ -1192,7 +1208,6 @@ struct sched_class { int (*select_task_rq)(struct task_struct *p, int task_cpu, int sd_flag, int flags); void (*migrate_task_rq)(struct task_struct *p, int next_cpu); - 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); -- 2.34.1