Re: [PATCH v2 2/3] sched/dl: Cleanup prio_changed_dl()
From: Wanpeng Li
Date: Thu Oct 23 2014 - 19:05:13 EST
10/22/14, 12:24 AM, Juri Lelli:
Hi Kirill,
On 02/10/14 10:52, Kirill Tkhai wrote:
Ð ÐÑ, 02/10/2014 Ð 11:36 +0200, Peter Zijlstra ÐÐÑÐÑ:
On Wed, Oct 01, 2014 at 01:04:35AM +0400, Kirill Tkhai wrote:
From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
rq->curr task can't be in "dequeued" state in prio_changed_dl().
(The only place we can have that is __schedule()). So, we delete
rq->curr check.
the CBS timer can throttle it right?
Yeah, it's better to check for on_dl_rq():
[PATCH]sched/dl: Cleanup prio_changed_dl()
rq->curr task can't be in "dequeued" state in prio_changed_dl().
(The only place we can have that is __schedule()). So, we delete
rq->curr check.
We shouldn't do balancing if deadline task is throttled too.
Also delete "else" branch which is dead code (switched_to_dl()
is not interested in dequeued tasks and we are not interested
in balancing in this case).
So, I agree that calling switched_to_dl() makes little sense,
but don't we have to deal with updates to not running tasks as
in rt.c? Something like this maybe?
From 75ee75a5fd76526baaed3ba8a58f3ff7daa89cd6 Mon Sep 17 00:00:00 2001
From: Juri Lelli <juri.lelli@xxxxxxx>
Date: Tue, 21 Oct 2014 17:15:15 +0100
Subject: [PATCH] sched/deadline: cleanup prio_changed_dl()
---
kernel/sched/deadline.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 28d6088..1e62e31 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1661,7 +1661,10 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
static void prio_changed_dl(struct rq *rq, struct task_struct *p,
int oldprio)
{
- if (task_on_rq_queued(p) || rq->curr == p) {
+ if (!on_dl_rq(&p->dl))
I'm not sure if this should be task_on_rq_queued() check. All
check_class_changed() callsites dequeue entity if task_on_rq_queued() is
true which leads to on_dl_rq(&p->dl) always return false.
Regards,
Wanpeng Li
+ return;
+
+ if (rq->curr == p) {
#ifdef CONFIG_SMP
/*
* This might be too much, but unfortunately
@@ -1688,8 +1691,15 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
*/
resched_curr(rq);
#endif /* CONFIG_SMP */
- } else
- switched_to_dl(rq, p);
+ } else {
+ /*
+ * This task is not running, so if its deadline is
+ * now more imminent than that of the current running
+ * task then reschedule.
+ */
+ if (dl_time_before(p->dl.deadline, rq->curr->dl.deadline))
+ resched_curr(rq);
+ }
}
const struct sched_class dl_sched_class = {
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/