Hi Kirill,
10/24/14, 2:01 PM, Kirill Tkhai:
Hi, Wanpeng,
the commit commentary confuses, I'm agree. Really it's just a cleanup.
On Пт, 2014-10-24 at 07:27 +0800, Wanpeng Li wrote:
Hi Kirill,
8/6/14, 4:06 PM, Kirill Tkhai:
(sched_entity::on_rq == 1) does not guarantee the task is pickable;
changes on throttled cfs_rq must not lead to reschedule.
Why (sched_entity::on_rq == 1) doesn't guarantee the task is pickable
since entity will be dequeued during throttling cfs_rq?
Because one of task's (grand)parents in hierarhy may be throtthed and
dequeued.
But task_struct::on_rq check doesn't guarantee this too. So, just ignore
commit commentary; the commentary is wrong.
Check for task_struct::on_rq instead.
Do you mean task_struct::on_rq will be cleared during throttling cfs_rq?
I can't find codes do this.
No, it not cleared. The commit commentary should be:
"sched: Cleanup. Check task_struct::on_rq instead of sched_entity::on_rq,
because it is the same for a task"
IIUR, for fair class, sched_entity::on_rq will be set/clear during
enqueue/dequeue, task_struct::on_rq will changed during task migration,
I'm not sure why they are the same.
Regards,
Wanpeng Li
Regards,
Wanpeng Li
Signed-off-by: Kirill Tkhai <ktk...@parallels.com>
---
kernel/sched/fair.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bfa3c86..6f0ce2b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7465,7 +7465,7 @@ static void task_fork_fair(struct task_struct *p)
static void
prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
{
- if (!p->se.on_rq)
+ if (!p->on_rq)
return;
/*
@@ -7521,15 +7521,15 @@ static void switched_from_fair(struct rq *rq, struct
task_struct *p)
*/
static void switched_to_fair(struct rq *rq, struct task_struct *p)
{
- struct sched_entity *se = &p->se;
#ifdef CONFIG_FAIR_GROUP_SCHED
+ struct sched_entity *se = &p->se;
/*
* Since the real-depth could have been changed (only FAIR
* class maintain depth value), reset depth properly.
*/
se->depth = se->parent ? se->parent->depth + 1 : 0;
#endif
- if (!se->on_rq)
+ if (!p->on_rq)
return;
/*
--
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