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sched: rework of "prioritize non-migratable tasks over migratable ones"

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(1) handle in a generic way all cases when a newly woken-up task is
not migratable (not just a corner case when "rt_se->nr_cpus_allowed ==
1")

(2) if current is to be preempted, then make sure "p" will be picked
up by pick_next_task_rt().
i.e. move task's group at the head of its list as well.

currently, it's not a case for the group-scheduling case as described
here: http://www.ussg.iu.edu/hypermail/linux/kernel/0807.0/0134.html

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Dmitry Adamushko 2008-07-01 23:32:15 +02:00 committed by Ingo Molnar
parent 13b40c1e40
commit 7ebefa8cee
1 changed files with 40 additions and 28 deletions
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66
kernel/sched_rt.c
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@ -599,11 +599,7 @@ static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
return;
if (rt_se->nr_cpus_allowed == 1)
list_add(&rt_se->run_list, queue);
else
list_add_tail(&rt_se->run_list, queue);
__set_bit(rt_se_prio(rt_se), array->bitmap);
inc_rt_tasks(rt_se, rt_rq);
@ -688,32 +684,34 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
* Put task to the end of the run list without the overhead of dequeue
* followed by enqueue.
*/
static
void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
static void
requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
{
struct rt_prio_array *array = &rt_rq->active;
if (on_rt_rq(rt_se)) {
list_del_init(&rt_se->run_list);
list_add_tail(&rt_se->run_list,
array->queue + rt_se_prio(rt_se));
struct rt_prio_array *array = &rt_rq->active;
struct list_head *queue = array->queue + rt_se_prio(rt_se);
if (head)
list_move(&rt_se->run_list, queue);
else
list_move_tail(&rt_se->run_list, queue);
}
}
static void requeue_task_rt(struct rq *rq, struct task_struct *p)
static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
{
struct sched_rt_entity *rt_se = &p->rt;
struct rt_rq *rt_rq;
for_each_sched_rt_entity(rt_se) {
rt_rq = rt_rq_of_se(rt_se);
requeue_rt_entity(rt_rq, rt_se);
requeue_rt_entity(rt_rq, rt_se, head);
}
}
static void yield_task_rt(struct rq *rq)
{
requeue_task_rt(rq, rq->curr);
requeue_task_rt(rq, rq->curr, 0);
}
#ifdef CONFIG_SMP
@ -753,6 +751,30 @@ static int select_task_rq_rt(struct task_struct *p, int sync)
*/
return task_cpu(p);
}
static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
{
cpumask_t mask;
if (rq->curr->rt.nr_cpus_allowed == 1)
return;
if (p->rt.nr_cpus_allowed != 1
&& cpupri_find(&rq->rd->cpupri, p, &mask))
return;
if (!cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
return;
/*
* There appears to be other cpus that can accept
* current and none to run 'p', so lets reschedule
* to try and push current away:
*/
requeue_task_rt(rq, p, 1);
resched_task(rq->curr);
}
#endif /* CONFIG_SMP */
/*
@ -778,18 +800,8 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
* to move current somewhere else, making room for our non-migratable
* task.
*/
if((p->prio == rq->curr->prio)
&& p->rt.nr_cpus_allowed == 1
&& rq->curr->rt.nr_cpus_allowed != 1) {
cpumask_t mask;
if (cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
/*
* There appears to be other cpus that can accept
* current, so lets reschedule to try and push it away
*/
resched_task(rq->curr);
}
if (p->prio == rq->curr->prio && !need_resched())
check_preempt_equal_prio(rq, p);
#endif
}
@ -1415,7 +1427,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
* on the queue:
*/
if (p->rt.run_list.prev != p->rt.run_list.next) {
requeue_task_rt(rq, p);
requeue_task_rt(rq, p, 0);
set_tsk_need_resched(p);
}
}