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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: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Dmitry Adamushko 2007-10-15 17:00:07 +02:00 committed by Ingo Molnar
parent 7074badbcb
commit 30cfdcfc5f
4 changed files with 36 additions and 22 deletions
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1
include/linux/sched.h
View File

@ -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;

1
kernel/sched.c
View File

@ -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;

2
kernel/sched_debug.c
View File

@ -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

54
kernel/sched_fair.c
View File

@ -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);
__enqueue_entity(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
__dequeue_entity(cfs_rq, se);
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);
}