Commit ff1cdc94 authored by Muchun Song's avatar Muchun Song Committed by Ingo Molnar
Browse files

sched/core: Introduce set_next_task() helper for better code readability 



When we pick the next task, we will do the following for the task:

  1) p->se.exec_start = rq_clock_task(rq);
  2) dequeue_pushable(_dl)_task(rq, p);

When we call set_curr_task(), we also need to do the same thing
above. In rt.c, the code at 1) is in the _pick_next_task_rt()
and the code at 2) is in the pick_next_task_rt(). If we put two
operations in one function, maybe better. So, we introduce a new
function set_next_task(), which is responsible for doing the above.

By introducing the function we can get rid of calling the
dequeue_pushable(_dl)_task() directly(We can call set_next_task())
in pick_next_task() and have better code readability and reuse.
In set_curr_task_rt(), we also can call set_next_task().

Do this things such that we end up with:

  static struct task_struct *pick_next_task(struct rq *rq,
  					    struct task_struct *prev,
  					    struct rq_flags *rf)
  {
  	/* do something else ... */

  	put_prev_task(rq, prev);

  	/* pick next task p */

  	set_next_task(rq, p);

  	/* do something else ... */
  }

put_prev_task() can match set_next_task(), which can make the
code more readable.

Signed-off-by: default avatarMuchun Song <smuchun@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181026131743.21786-1-smuchun@gmail.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3f130a37

kernel/sched/deadline.c

+10 −9
Original line number Diff line number Diff line
@@ -1695,6 +1695,14 @@ static void start_hrtick_dl(struct rq *rq, struct task_struct *p) 
}

#endif



static inline void set_next_task(struct rq *rq, struct task_struct *p)

{

	p->se.exec_start = rq_clock_task(rq);



	/* You can't push away the running task */

	dequeue_pushable_dl_task(rq, p);

}



static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,

						   struct dl_rq *dl_rq)

{
@@ -1750,10 +1758,8 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) 
	BUG_ON(!dl_se);



	p = dl_task_of(dl_se);

	p->se.exec_start = rq_clock_task(rq);



	/* Running task will never be pushed. */

       dequeue_pushable_dl_task(rq, p);

	set_next_task(rq, p);



	if (hrtick_enabled(rq))

		start_hrtick_dl(rq, p);
@@ -1808,12 +1814,7 @@ static void task_fork_dl(struct task_struct *p) 


static void set_curr_task_dl(struct rq *rq)

{

	struct task_struct *p = rq->curr;



	p->se.exec_start = rq_clock_task(rq);



	/* You can't push away the running task */

	dequeue_pushable_dl_task(rq, p);

	set_next_task(rq, rq->curr);

}



#ifdef CONFIG_SMP

kernel/sched/rt.c

+11 −13
Original line number Diff line number Diff line
@@ -1498,6 +1498,14 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flag 
#endif

}



static inline void set_next_task(struct rq *rq, struct task_struct *p)

{

	p->se.exec_start = rq_clock_task(rq);



	/* The running task is never eligible for pushing */

	dequeue_pushable_task(rq, p);

}



static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,

						   struct rt_rq *rt_rq)

{
@@ -1518,7 +1526,6 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq, 
static struct task_struct *_pick_next_task_rt(struct rq *rq)

{

	struct sched_rt_entity *rt_se;

	struct task_struct *p;

	struct rt_rq *rt_rq  = &rq->rt;



	do {
@@ -1527,10 +1534,7 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq) 
		rt_rq = group_rt_rq(rt_se);

	} while (rt_rq);



	p = rt_task_of(rt_se);

	p->se.exec_start = rq_clock_task(rq);



	return p;

	return rt_task_of(rt_se);

}



static struct task_struct *
@@ -1573,8 +1577,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) 


	p = _pick_next_task_rt(rq);



	/* The running task is never eligible for pushing */

	dequeue_pushable_task(rq, p);

	set_next_task(rq, p);



	rt_queue_push_tasks(rq);
@@ -2355,12 +2358,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued) 


static void set_curr_task_rt(struct rq *rq)

{

	struct task_struct *p = rq->curr;



	p->se.exec_start = rq_clock_task(rq);



	/* The running task is never eligible for pushing */

	dequeue_pushable_task(rq, p);

	set_next_task(rq, rq->curr);

}



static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)

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