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Commit 30cfdcfc authored by Dmitry Adamushko's avatar Dmitry Adamushko Committed by Ingo Molnar
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sched: do not keep current in the tree and get rid of sched_entity::fair_key 



Get rid of 'sched_entity::fair_key'.

As a side effect, 'current' is not kept withing the tree for 
SCHED_NORMAL/BATCH tasks anymore. This simplifies some parts of code 
(e.g. entity_tick() and yield_task_fair()) and also somewhat optimizes 
them (e.g. a single update_curr() now vs. dequeue/enqueue() before in 
entity_tick()).

Signed-off-by: default avatarDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 7074badb

include/linux/sched.h

+0 −1
Original line number Diff line number Diff line
@@ -891,7 +891,6 @@ struct load_weight { 
 *     6 se->load.weight

 */

struct sched_entity {

	s64			fair_key;

	struct load_weight	load;		/* for load-balancing */

	struct rb_node		run_node;

	unsigned int		on_rq;

kernel/sched.c

+0 −1
Original line number Diff line number Diff line
@@ -6610,7 +6610,6 @@ void normalize_rt_tasks(void) 


	read_lock_irq(&tasklist_lock);

	do_each_thread(g, p) {

		p->se.fair_key			= 0;

		p->se.exec_start		= 0;

#ifdef CONFIG_SCHEDSTATS

		p->se.wait_start		= 0;

kernel/sched_debug.c

+1 −1
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p) 


	SEQ_printf(m, "%15s %5d %15Ld %13Ld %5d ",

		p->comm, p->pid,

		(long long)p->se.fair_key,

		(long long)p->se.vruntime,

		(long long)(p->nvcsw + p->nivcsw),

		p->prio);

#ifdef CONFIG_SCHEDSTATS

kernel/sched_fair.c

+35 −19
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ set_leftmost(struct cfs_rq *cfs_rq, struct rb_node *leftmost) 
static inline s64

entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	return se->fair_key - cfs_rq->min_vruntime;

	return se->vruntime - cfs_rq->min_vruntime;

}



/*
@@ -181,9 +181,6 @@ __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) 


	rb_link_node(&se->run_node, parent, link);

	rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);

	update_load_add(&cfs_rq->load, se->load.weight);

	cfs_rq->nr_running++;

	se->on_rq = 1;

}



static void
@@ -193,9 +190,6 @@ __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) 
		set_leftmost(cfs_rq, rb_next(&se->run_node));



	rb_erase(&se->run_node, &cfs_rq->tasks_timeline);

	update_load_sub(&cfs_rq->load, se->load.weight);

	cfs_rq->nr_running--;

	se->on_rq = 0;

}



static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
@@ -341,10 +335,6 @@ static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) 
	 */

	if (se != cfs_rq->curr)

		update_stats_wait_start(cfs_rq, se);

	/*

	 * Update the key:

	 */

	se->fair_key = se->vruntime;

}



static void
@@ -392,6 +382,22 @@ update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se) 
 * Scheduling class queueing methods:

 */



static void

account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	update_load_add(&cfs_rq->load, se->load.weight);

	cfs_rq->nr_running++;

	se->on_rq = 1;

}



static void

account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	update_load_sub(&cfs_rq->load, se->load.weight);

	cfs_rq->nr_running--;

	se->on_rq = 0;

}



static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

#ifdef CONFIG_SCHEDSTATS
@@ -479,7 +485,9 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup) 
	}



	update_stats_enqueue(cfs_rq, se);

	if (se != cfs_rq->curr)

		__enqueue_entity(cfs_rq, se);

	account_entity_enqueue(cfs_rq, se);

}



static void
@@ -498,7 +506,9 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep) 
		}

	}

#endif

	if (se != cfs_rq->curr)

		__dequeue_entity(cfs_rq, se);

	account_entity_dequeue(cfs_rq, se);

}



/*
@@ -544,6 +554,10 @@ static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) 
{

	struct sched_entity *se = __pick_next_entity(cfs_rq);



	/* 'current' is not kept within the tree. */

	if (se)

		__dequeue_entity(cfs_rq, se);



	set_next_entity(cfs_rq, se);



	return se;
@@ -560,19 +574,20 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) 


	update_stats_curr_end(cfs_rq, prev);



	if (prev->on_rq)

	if (prev->on_rq) {

		update_stats_wait_start(cfs_rq, prev);

		/* Put 'current' back into the tree. */

		__enqueue_entity(cfs_rq, prev);

	}

	cfs_rq->curr = NULL;

}



static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)

{

	/*

	 * Dequeue and enqueue the task to update its

	 * position within the tree:

	 * Update run-time statistics of the 'current'.

	 */

	dequeue_entity(cfs_rq, curr, 0);

	enqueue_entity(cfs_rq, curr, 0);

	update_curr(cfs_rq);



	if (cfs_rq->nr_running > 1)

		check_preempt_tick(cfs_rq, curr);
@@ -749,7 +764,7 @@ static void yield_task_fair(struct rq *rq, struct task_struct *p) 
	/*

	 * Minimally necessary key value to be last in the tree:

	 */

	se->fair_key = rightmost->fair_key + 1;

	se->vruntime = rightmost->vruntime + 1;



	if (cfs_rq->rb_leftmost == &se->run_node)

		cfs_rq->rb_leftmost = rb_next(&se->run_node);
@@ -965,6 +980,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) 


	update_stats_enqueue(cfs_rq, se);

	__enqueue_entity(cfs_rq, se);

	account_entity_enqueue(cfs_rq, se);

	resched_task(rq->curr);

}