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sched: redundant reschedule when set_user_nice() boosts a prio of a task from the "expired" array

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- Make TASK_PREEMPTS_CURR(task, rq) return "true" only if the task's prio
  is higher than the current's one and the task is in the "active" array.
  This ensures we don't make redundant resched_task() calls when the task
  is in the "expired" array (as may happen now in set_user_prio(),
  rt_mutex_setprio() and pull_task() ) ;

- generalise conditions for a call to resched_task() in set_user_nice(),
  rt_mutex_setprio() and sched_setscheduler()

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dmitry Adamushko 2007-05-08 00:33:06 -07:00 committed by Linus Torvalds
parent 4953198b6c
commit bd53f96ca5
1 changed files with 16 additions and 18 deletions
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34
kernel/sched.c
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@ -169,7 +169,7 @@ unsigned long long __attribute__((weak)) sched_clock(void)
(MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
#define TASK_PREEMPTS_CURR(p, rq) \
((p)->prio < (rq)->curr->prio)
(((p)->prio < (rq)->curr->prio) && ((p)->array == (rq)->active))
#define SCALE_PRIO(x, prio) \
max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
@ -4076,13 +4076,13 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
struct prio_array *array;
unsigned long flags;
struct rq *rq;
int oldprio;
int delta;
BUG_ON(prio < 0 || prio > MAX_PRIO);
rq = task_rq_lock(p, &flags);
oldprio = p->prio;
delta = prio - p->prio;
array = p->array;
if (array)
dequeue_task(p, array);
@ -4098,13 +4098,11 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
enqueue_task(p, array);
/*
* Reschedule if we are currently running on this runqueue and
* our priority decreased, or if we are not currently running on
* this runqueue and our priority is higher than the current's
* our priority decreased, or if our priority became higher
* than the current's.
*/
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
} else if (TASK_PREEMPTS_CURR(p, rq))
if (TASK_PREEMPTS_CURR(p, rq) ||
(delta > 0 && task_running(rq, p)))
resched_task(rq->curr);
}
task_rq_unlock(rq, &flags);
@ -4152,10 +4150,12 @@ void set_user_nice(struct task_struct *p, long nice)
enqueue_task(p, array);
inc_raw_weighted_load(rq, p);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
* Reschedule if we are currently running on this runqueue and
* our priority decreased, or if our priority became higher
* than the current's.
*/
if (delta < 0 || (delta > 0 && task_running(rq, p)))
if (TASK_PREEMPTS_CURR(p, rq) ||
(delta > 0 && task_running(rq, p)))
resched_task(rq->curr);
}
out_unlock:
@ -4382,13 +4382,11 @@ int sched_setscheduler(struct task_struct *p, int policy,
__activate_task(p, rq);
/*
* Reschedule if we are currently running on this runqueue and
* our priority decreased, or if we are not currently running on
* this runqueue and our priority is higher than the current's
* our priority decreased, or our priority became higher
* than the current's.
*/
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
} else if (TASK_PREEMPTS_CURR(p, rq))
if (TASK_PREEMPTS_CURR(p, rq) ||
(task_running(rq, p) && p->prio > oldprio))
resched_task(rq->curr);
}
__task_rq_unlock(rq);