[PATCH 02/18] sched: Use replace normalize_task() with __sched_setscheduler()

Peter Zijlstra
2015-06-11T12:56:46Z

[-- Attachment #1: peterz-sched-post_schedule-6.patch --]
[-- Type: text/plain, Size: 3953 bytes --]

Reduce duplicate logic; normalize_task() is a simplified version of
__sched_setscheduler(). Parametrize the difference and collapse.

This reduces the amount of check_class_changed() sites.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/core.c | 65 ++++++++++++++++++----------------------------------
1 file changed, 23 insertions(+), 42 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3428,7 +3428,7 @@ static bool dl_param_changed(struct task

static int __sched_setscheduler(struct task_struct *p,
const struct sched_attr *attr,
- bool user)
+ bool user, bool pi)
{
int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
MAX_RT_PRIO - 1 - attr->sched_priority;
@@ -3614,18 +3614,20 @@ static int __sched_setscheduler(struct t
p->sched_reset_on_fork = reset_on_fork;
oldprio = p->prio;

- /*
- * Take priority boosted tasks into account. If the new
- * effective priority is unchanged, we just store the new
- * normal parameters and do not touch the scheduler class and
- * the runqueue. This will be done when the task deboost
- * itself.
- */
- new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
- if (new_effective_prio == oldprio) {
- __setscheduler_params(p, attr);
- task_rq_unlock(rq, p, &flags);
- return 0;
+ if (pi) {
+ /*
+ * Take priority boosted tasks into account. If the new
+ * effective priority is unchanged, we just store the new
+ * normal parameters and do not touch the scheduler class and
+ * the runqueue. This will be done when the task deboost
+ * itself.
+ */
+ new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
+ if (new_effective_prio == oldprio) {
+ __setscheduler_params(p, attr);
+ task_rq_unlock(rq, p, &flags);
+ return 0;
+ }
}

queued = task_on_rq_queued(p);
@@ -3636,7 +3638,7 @@ static int __sched_setscheduler(struct t
put_prev_task(rq, p);

prev_class = p->sched_class;
- __setscheduler(rq, p, attr, true);
+ __setscheduler(rq, p, attr, pi);

if (running)
p->sched_class->set_curr_task(rq);
@@ -3651,7 +3653,8 @@ static int __sched_setscheduler(struct t
check_class_changed(rq, p, prev_class, oldprio);
task_rq_unlock(rq, p, &flags);

- rt_mutex_adjust_pi(p);
+ if (pi)
+ rt_mutex_adjust_pi(p);

return 0;
}
@@ -3672,7 +3675,7 @@ static int _sched_setscheduler(struct ta
attr.sched_policy = policy;
}

- return __sched_setscheduler(p, &attr, check);
+ return __sched_setscheduler(p, &attr, check, true);
}
/**
* sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
@@ -3693,7 +3696,7 @@ EXPORT_SYMBOL_GPL(sched_setscheduler);

int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
{
- return __sched_setscheduler(p, attr, true);
+ return __sched_setscheduler(p, attr, true, true);
}
EXPORT_SYMBOL_GPL(sched_setattr);

@@ -7354,32 +7357,12 @@ EXPORT_SYMBOL(___might_sleep);
#endif

#ifdef CONFIG_MAGIC_SYSRQ
-static void normalize_task(struct rq *rq, struct task_struct *p)
+void normalize_rt_tasks(void)
{
- const struct sched_class *prev_class = p->sched_class;
+ struct task_struct *g, *p;
struct sched_attr attr = {
.sched_policy = SCHED_NORMAL,
};
- int old_prio = p->prio;
- int queued;
-
- queued = task_on_rq_queued(p);
- if (queued)
- dequeue_task(rq, p, 0);
- __setscheduler(rq, p, &attr, false);
- if (queued) {
- enqueue_task(rq, p, 0);
- resched_curr(rq);
- }
-
- check_class_changed(rq, p, prev_class, old_prio);
-}
-
-void normalize_rt_tasks(void)
-{
- struct task_struct *g, *p;
- unsigned long flags;
- struct rq *rq;

read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
@@ -7406,9 +7389,7 @@ void normalize_rt_tasks(void)
continue;
}

- rq = task_rq_lock(p, &flags);
- normalize_task(rq, p);
- task_rq_unlock(rq, p, &flags);
+ __sched_setscheduler(p, &attr, false, false);
}
read_unlock(&tasklist_lock);
}