3.16.36-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Peter Zijlstra <pet...@infradead.org> 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) <pet...@infradead.org> Cc: ktk...@parallels.com Cc: rost...@goodmis.org Cc: juri.le...@gmail.com Cc: pang.xun...@linaro.org Cc: o...@redhat.com Cc: wanpeng...@linux.intel.com Cc: umgwanakikb...@gmail.com Link: http://lkml.kernel.org/r/20150611124742.424032...@infradead.org Signed-off-by: Thomas Gleixner <t...@linutronix.de> [Conflicts: kernel/sched/core.c] Signed-off-by: Byungchul Park <byungchul.p...@lge.com> Signed-off-by: Ben Hutchings <b...@decadent.org.uk> --- 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(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2258,23 +2258,35 @@ static void finish_task_switch(struct rq #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) { } @@ -2295,7 +2307,7 @@ asmlinkage __visible void schedule_tail( * 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 */ @@ -2822,7 +2834,7 @@ need_resched: } else raw_spin_unlock_irq(&rq->lock); - post_schedule(rq); + balance_callback(rq); sched_preempt_enable_no_resched(); if (need_resched()) @@ -7001,7 +7013,7 @@ void __init sched_init(void) rq->sd = NULL; rq->rd = NULL; rq->cpu_capacity = SCHED_CAPACITY_SCALE; - rq->post_schedule = 0; + rq->balance_callback = NULL; rq->active_balance = 0; rq->next_balance = jiffies; rq->push_cpu = 0; --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -213,9 +213,16 @@ static inline bool need_pull_dl_task(str 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); } #else @@ -250,7 +257,7 @@ static inline int pull_dl_task(struct rq return 0; } -static inline void set_post_schedule(struct rq *rq) +static inline void queue_push_tasks(struct rq *rq) { } #endif /* CONFIG_SMP */ @@ -1043,7 +1050,7 @@ struct task_struct *pick_next_task_dl(st start_hrtick_dl(rq, p); #endif - set_post_schedule(rq); + queue_push_tasks(rq); return p; } @@ -1452,11 +1459,6 @@ 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. @@ -1644,7 +1646,6 @@ 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 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -338,13 +338,16 @@ static inline int has_pushable_tasks(str 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) @@ -401,7 +404,7 @@ static inline int pull_rt_task(struct rq return 0; } -static inline void set_post_schedule(struct rq *rq) +static inline void queue_push_tasks(struct rq *rq) { } #endif /* CONFIG_SMP */ @@ -1472,7 +1475,7 @@ pick_next_task_rt(struct rq *rq, struct if (p) dequeue_pushable_task(rq, p); - set_post_schedule(rq); + queue_push_tasks(rq); return p; } @@ -1852,11 +1855,6 @@ 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 @@ -2128,7 +2126,6 @@ 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 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -569,9 +569,10 @@ struct rq { unsigned long cpu_capacity; + 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; @@ -670,6 +671,21 @@ extern int migrate_swap(struct task_stru #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) \ @@ -1127,7 +1143,6 @@ 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);
