[PATCH 1/4 v2] Replace hooks with pre/post schedule and wakeup methods

[Steven Rostedt]

To make the main sched.c code more agnostic to the schedule classes.
Instead of having specific hooks in the schedule code for the RT class
balancing. They are replaced with a pre_schedule, post_schedule
and task_wake_up methods. These methods may be used by any of the classes
but currently, only the sched_rt class implements them.

Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
---
 include/linux/sched.h |    3 +++
 kernel/sched.c        |   20 ++++++++++++++++----
 kernel/sched_rt.c     |   17 +++++++----------
 3 files changed, 26 insertions(+), 14 deletions(-)

Index: linux-sched/include/linux/sched.h
===================================================================
--- linux-sched.orig/include/linux/sched.h	2007-12-10 20:39:11.000000000 -0500
+++ linux-sched/include/linux/sched.h	2007-12-10 20:39:14.000000000 -0500
@@ -848,6 +848,9 @@ struct sched_class {
 	int (*move_one_task) (struct rq *this_rq, int this_cpu,
 			      struct rq *busiest, struct sched_domain *sd,
 			      enum cpu_idle_type idle);
+	void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
+	void (*post_schedule) (struct rq *this_rq);
+	void (*task_wake_up) (struct rq *this_rq, struct task_struct *task);
 #endif
 
 	void (*set_curr_task) (struct rq *rq);
Index: linux-sched/kernel/sched.c
===================================================================
--- linux-sched.orig/kernel/sched.c	2007-12-10 20:39:11.000000000 -0500
+++ linux-sched/kernel/sched.c	2007-12-10 20:39:14.000000000 -0500
@@ -1620,7 +1620,10 @@ out_activate:
 
 out_running:
 	p->state = TASK_RUNNING;
-	wakeup_balance_rt(rq, p);
+#ifdef CONFIG_SMP
+	if (p->sched_class->task_wake_up)
+		p->sched_class->task_wake_up(rq, p);
+#endif
 out:
 	task_rq_unlock(rq, &flags);
 
@@ -1743,7 +1746,10 @@ void fastcall wake_up_new_task(struct ta
 		inc_nr_running(p, rq);
 	}
 	check_preempt_curr(rq, p);
-	wakeup_balance_rt(rq, p);
+#ifdef CONFIG_SMP
+	if (p->sched_class->task_wake_up)
+		p->sched_class->task_wake_up(rq, p);
+#endif
 	task_rq_unlock(rq, &flags);
 }
 
@@ -1864,7 +1870,10 @@ static void finish_task_switch(struct rq
 	prev_state = prev->state;
 	finish_arch_switch(prev);
 	finish_lock_switch(rq, prev);
-	schedule_tail_balance_rt(rq);
+#ifdef CONFIG_SMP
+	if (current->sched_class->post_schedule)
+		current->sched_class->post_schedule(rq);
+#endif
 
 	fire_sched_in_preempt_notifiers(current);
 	if (mm)
@@ -3633,7 +3642,10 @@ need_resched_nonpreemptible:
 		switch_count = &prev->nvcsw;
 	}
 
-	schedule_balance_rt(rq, prev);
+#ifdef CONFIG_SMP
+	if (prev->sched_class->pre_schedule)
+		prev->sched_class->pre_schedule(rq, prev);
+#endif
 
 	if (unlikely(!rq->nr_running))
 		idle_balance(cpu, rq);
Index: linux-sched/kernel/sched_rt.c
===================================================================
--- linux-sched.orig/kernel/sched_rt.c	2007-12-10 20:39:11.000000000 -0500
+++ linux-sched/kernel/sched_rt.c	2007-12-10 20:39:14.000000000 -0500
@@ -689,14 +689,14 @@ static int pull_rt_task(struct rq *this_
 	return ret;
 }
 
-static void schedule_balance_rt(struct rq *rq, struct task_struct *prev)
+static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
 {
 	/* Try to pull RT tasks here if we lower this rq's prio */
 	if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
 		pull_rt_task(rq);
 }
 
-static void schedule_tail_balance_rt(struct rq *rq)
+static void post_schedule_rt(struct rq *rq)
 {
 	/*
 	 * If we have more than one rt_task queued, then
@@ -713,10 +713,9 @@ static void schedule_tail_balance_rt(str
 }
 
 
-static void wakeup_balance_rt(struct rq *rq, struct task_struct *p)
+static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
 {
-	if (unlikely(rt_task(p)) &&
-	    !task_running(rq, p) &&
+	if (!task_running(rq, p) &&
 	    (p->prio >= rq->rt.highest_prio) &&
 	    rq->rt.overloaded)
 		push_rt_tasks(rq);
@@ -780,11 +779,6 @@ static void leave_domain_rt(struct rq *r
 	if (rq->rt.overloaded)
 		rt_clear_overload(rq);
 }
-
-#else /* CONFIG_SMP */
-# define schedule_tail_balance_rt(rq)	do { } while (0)
-# define schedule_balance_rt(rq, prev)	do { } while (0)
-# define wakeup_balance_rt(rq, p)	do { } while (0)
 #endif /* CONFIG_SMP */
 
 static void task_tick_rt(struct rq *rq, struct task_struct *p)
@@ -838,6 +832,9 @@ const struct sched_class rt_sched_class 
 	.set_cpus_allowed       = set_cpus_allowed_rt,
 	.join_domain            = join_domain_rt,
 	.leave_domain           = leave_domain_rt,
+	.pre_schedule		= pre_schedule_rt,
+	.post_schedule		= post_schedule_rt,
+	.task_wake_up		= task_wake_up_rt,
 #endif
 
 	.set_curr_task          = set_curr_task_rt,

-- 
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