linux-kernel - Re: [PATCH] sched: Remove WAKEUP_PREEMPT feature check in entity

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Date:	Fri, 29 Jul 2011 14:24:49 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Lin Ming <ming.m.lin@...el.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>, mingo@...e.hu,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sched: Remove WAKEUP_PREEMPT feature check in entity_tick

On Fri, Jul 29, 2011 at 2:21 PM, Yong Zhang <yong.zhang0@...il.com> wrote:
> On Thu, Jul 28, 2011 at 05:43:23PM +0800, Lin Ming wrote:
>> Currently, entity_tick calls check_preempt_tick if WAKEUP_PREEMPT feature is
>> disabled. That's wrong. It should do that if the feature is enabled.
>
> Why is it wrong?
> check_preempt_wakeup() is used for wakeup.
>
>>
>> And actually the check is duplicate because check_preempt_tick will do
>> that. So just remove it from entity_tick.
>
> It's not exactly duplicated. entity_tick() will resched_task(*p)

s/entity_tick/check_preempt_tick

> if p's slice is over. So if there is an following wakeup(say X),
> then there is an opportunity for X to schedule quickly.
>
> Thanks,
> Yong
>
>>
>> Signed-off-by: Lin Ming <ming.m.lin@...el.com>
>> ---
>>  kernel/sched_fair.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
>> index bc8ee99..af2fe9d 100644
>> --- a/kernel/sched_fair.c
>> +++ b/kernel/sched_fair.c
>> @@ -1233,7 +1233,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
>>               return;
>>  #endif
>>
>> -     if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
>> +     if (cfs_rq->nr_running > 1)
>>               check_preempt_tick(cfs_rq, curr);
>>  }
>>
>> --
>> 1.7.2.3
>>
>>
>>
>> --
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>
> --
> Only stand for myself
>



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