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sched: RT-balance, add new methods to sched_class

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Dmitry Adamushko found that the current implementation of the RT
balancing code left out changes to the sched_setscheduler and
rt_mutex_setprio.

This patch addresses this issue by adding methods to the schedule classes
to handle being switched out of (switched_from) and being switched into
(switched_to) a sched_class. Also a method for changing of priorities
is also added (prio_changed).

This patch also removes some duplicate logic between rt_mutex_setprio and
sched_setscheduler.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt
2008-01-25 21:08:22 +01:00
committed by Ingo Molnar
parent 9a897c5a67
commit cb46984504
5 changed files with 186 additions and 22 deletions
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89
kernel/sched_rt.c
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@@ -779,8 +779,93 @@ static void leave_domain_rt(struct rq *rq)
if (rq->rt.overloaded)
rt_clear_overload(rq);
}
/*
* When switch from the rt queue, we bring ourselves to a position
* that we might want to pull RT tasks from other runqueues.
*/
static void switched_from_rt(struct rq *rq, struct task_struct *p,
int running)
{
/*
* If there are other RT tasks then we will reschedule
* and the scheduling of the other RT tasks will handle
* the balancing. But if we are the last RT task
* we may need to handle the pulling of RT tasks
* now.
*/
if (!rq->rt.rt_nr_running)
pull_rt_task(rq);
}
#endif /* CONFIG_SMP */
/*
* When switching a task to RT, we may overload the runqueue
* with RT tasks. In this case we try to push them off to
* other runqueues.
*/
static void switched_to_rt(struct rq *rq, struct task_struct *p,
int running)
{
int check_resched = 1;
/*
* If we are already running, then there's nothing
* that needs to be done. But if we are not running
* we may need to preempt the current running task.
* If that current running task is also an RT task
* then see if we can move to another run queue.
*/
if (!running) {
#ifdef CONFIG_SMP
if (rq->rt.overloaded && push_rt_task(rq) &&
/* Don't resched if we changed runqueues */
rq != task_rq(p))
check_resched = 0;
#endif /* CONFIG_SMP */
if (check_resched && p->prio < rq->curr->prio)
resched_task(rq->curr);
}
}
/*
* Priority of the task has changed. This may cause
* us to initiate a push or pull.
*/
static void prio_changed_rt(struct rq *rq, struct task_struct *p,
int oldprio, int running)
{
if (running) {
#ifdef CONFIG_SMP
/*
* If our priority decreases while running, we
* may need to pull tasks to this runqueue.
*/
if (oldprio < p->prio)
pull_rt_task(rq);
/*
* If there's a higher priority task waiting to run
* then reschedule.
*/
if (p->prio > rq->rt.highest_prio)
resched_task(p);
#else
/* For UP simply resched on drop of prio */
if (oldprio < p->prio)
resched_task(p);
#endif /* CONFIG_SMP */
} else {
/*
* This task is not running, but if it is
* greater than the current running task
* then reschedule.
*/
if (p->prio < rq->curr->prio)
resched_task(rq->curr);
}
}
static void task_tick_rt(struct rq *rq, struct task_struct *p)
{
update_curr_rt(rq);
@@ -837,8 +922,12 @@ const struct sched_class rt_sched_class = {
.pre_schedule = pre_schedule_rt,
.post_schedule = post_schedule_rt,
.task_wake_up = task_wake_up_rt,
.switched_from = switched_from_rt,
#endif
.set_curr_task = set_curr_task_rt,
.task_tick = task_tick_rt,
.prio_changed = prio_changed_rt,
.switched_to = switched_to_rt,
};