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Groups > linux.kernel > #1220467
| From | Wanpeng Li <wanpeng.li@hotmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() |
| Date | 2015-09-08 05:50 +0200 |
| Message-ID | <q6i4W-RN-3@gated-at.bofh.it> (permalink) |
| References | <q61dM-1OC-25@gated-at.bofh.it> <q65hn-7Mu-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 9/7/15 10:02 PM, Peter Zijlstra wrote:
> Please always Cc at least the person who wrote the lines you modify.
>
> On Mon, Sep 07, 2015 at 05:45:20PM +0800, Wanpeng Li wrote:
>> The sleeper task will be normalized when moved from fair_sched_class, in
>> order that vruntime will be adjusted either the task is running or sleeping
>> when moved back. The nomalization in switch_to_fair for sleep task will
>> result in lose fair sleeper bonus in place_entity() once the vruntime -
>> cfs_rq->min_vruntime is big when moved from fair_sched_class.
>>
>> This patch fix it by adjusting vruntime just during migrating as original
>> codes since the vruntime of the task has usually NOT been normalized in
>> this case.
> Sorry, I cannot follow that at all. Maybe its me being sleep deprived,
> but could you try that again?
When changing away from the fair class while sleeping, relative vruntime
is calculated to handle the case sleep when moved from fair_sched_class
and running when moved to fair_sched_class. The absolute vruntime will
be calculated in enqueue_entity() either the task is running or sleeping
when moved back. The fair sleeper bonus should be gained in
place_entity() if the task is still sleeping. However, after recent
commit ( 23ec30ddd7c1306: 'sched: add two functions for att(det)aching a
task to(from) a cfs_rq'), the absolute vruntime will be calculated in
switched_to_fair(), so the max_vruntime() which is called in
place_entity() will select the absolute vruntime which is calculated in
switched_to_fair() as the se->vruntime and lose the fair sleeper bonus.
Regards,
Wanpeng Li
>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>> ---
>> kernel/sched/fair.c | 11 +++++++----
>> 1 files changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index d26d3b7..eb9aa35 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -8005,9 +8005,6 @@ static void attach_task_cfs_rq(struct task_struct *p)
>>
>> /* Synchronize task with its cfs_rq */
>> attach_entity_load_avg(cfs_rq, se);
>> -
>> - if (!vruntime_normalized(p))
>> - se->vruntime += cfs_rq->min_vruntime;
>> }
>>
>> static void switched_from_fair(struct rq *rq, struct task_struct *p)
>> @@ -8066,14 +8063,20 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
>> #ifdef CONFIG_FAIR_GROUP_SCHED
>> static void task_move_group_fair(struct task_struct *p)
>> {
>> + struct sched_entity *se = &p->se;
>> + struct cfs_rq *cfs_rq = cfs_rq_of(se);
>> +
>> detach_task_cfs_rq(p);
>> set_task_rq(p, task_cpu(p));
>>
>> #ifdef CONFIG_SMP
>> /* Tell se's cfs_rq has been changed -- migrated */
>> - p->se.avg.last_update_time = 0;
>> + se->avg.last_update_time = 0;
>> #endif
>> attach_task_cfs_rq(p);
>> +
>> + if (!vruntime_normalized(p))
>> + se->vruntime += cfs_rq->min_vruntime;
>> }
>>
>> void free_fair_sched_group(struct task_group *tg)
>> --
>> 1.7.1
>>
--
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[PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-07 11:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Peter Zijlstra <peterz@infradead.org> - 2015-09-07 16:10 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 05:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 07:30 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 07:40 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 08:20 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 08:30 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 08:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 08:40 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 08:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 09:20 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 09:40 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 10:00 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 10:10 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 10:30 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 10:40 +0200
RE: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() "byungchul.park" <byungchul.park@lge.com> - 2015-09-08 10:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 10:50 +0200
RE: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() "byungchul.park" <byungchul.park@lge.com> - 2015-09-08 11:00 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 11:20 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Peter Zijlstra <peterz@infradead.org> - 2015-09-08 13:30 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 08:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Peter Zijlstra <peterz@infradead.org> - 2015-09-08 11:50 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Byungchul Park <byungchul.park@lge.com> - 2015-09-08 04:20 +0200
Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-08 09:00 +0200
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