[PATCH v3 2/5] sched/deadline: make init_sched_dl_class() __init

[PATCH v3 2/5] sched/deadline: make init_sched_dl_class() __init

[Wanpeng Li]

It's a bootstrap function, make init_sched_dl_class() __init.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 kernel/sched/deadline.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f09f3ad..4303af2 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1686,7 +1686,7 @@ static void rq_offline_dl(struct rq *rq)
 	cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
 }
 
-void init_sched_dl_class(void)
+void __init init_sched_dl_class(void)
 {
 	unsigned int i;
 
-- 
1.9.1

[PATCH v3 3/5] sched/deadline: reduce rq lock contention by eliminating locking of non-feasible target

[Wanpeng Li]

This patch adds check that prevents futile attempts to move dl tasks to
a CPU with active tasks of equal or earlier deadline. The same behavior as
commit 80e3d87b2c55 ("sched/rt: Reduce rq lock contention by eliminating
locking of non-feasible target") for rt class.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
v1 -> v2:
 * add check in find_lock_later_rq()

 kernel/sched/deadline.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 4303af2..e49b1e6 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1012,7 +1012,9 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
 	    (p->nr_cpus_allowed > 1)) {
 		int target = find_later_rq(p);
 
-		if (target != -1)
+		if (target != -1 &&
+				dl_time_before(p->dl.deadline,
+					cpu_rq(target)->dl.earliest_dl.curr))
 			cpu = target;
 	}
 	rcu_read_unlock();
@@ -1360,6 +1362,17 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
 
 		later_rq = cpu_rq(cpu);
 
+		if (!dl_time_before(task->dl.deadline,
+					later_rq->dl.earliest_dl.curr)) {
+			/*
+			 * Target rq has tasks of equal or earlier deadline,
+			 * retrying does not release any lock and is unlikely
+			 * to yield a different result.
+			 */
+			later_rq = NULL;
+			break;
+		}
+
 		/* Retry if something changed. */
 		if (double_lock_balance(rq, later_rq)) {
 			if (unlikely(task_rq(task) != rq ||
-- 
1.9.1

[PATCH v3 4/5] sched/deadline: drop duplicate init_sched_dl_class declaration

[Wanpeng Li]

There are two init_sched_dl_class declarations, this patch drop
the duplicated one.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
v1 -> v2:
 * trim the changelog

 kernel/sched/sched.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index d854555..d62b288 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1290,7 +1290,6 @@ extern void update_max_interval(void);
 extern void init_sched_dl_class(void);
 extern void init_sched_rt_class(void);
 extern void init_sched_fair_class(void);
-extern void init_sched_dl_class(void);
 
 extern void resched_curr(struct rq *rq);
 extern void resched_cpu(int cpu);
-- 
1.9.1

[PATCH v3 5/5] sched/core: remove superfluous resetting of dl_throttled flag

[Wanpeng Li]

Resetting dl_throttled flag in rt_mutex_setprio (for a task that is going
to be boosted) is superfluous, as the natural place to do so is in
replenish_dl_entity(). If the task was on the runqueue and it is boosted
by a DL task, it will be enqueued back with ENQUEUE_REPLENISH flag set,
which can guarantee that dl_throttled is reset in replenish_dl_entity().

This patch drops the resetting of throttled status in function
rt_mutex_setprio().

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
v1 -> v2:
 * rewrite patch subject and changelog

 kernel/sched/core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5140db6..ef2ddd6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3076,7 +3076,6 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 		if (!dl_prio(p->normal_prio) ||
 		    (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
 			p->dl.dl_boosted = 1;
-			p->dl.dl_throttled = 0;
 			enqueue_flag = ENQUEUE_REPLENISH;
 		} else
 			p->dl.dl_boosted = 0;
-- 
1.9.1