linux-kernel - Re: [PATCH 1/7 v4] sched: factorize attach entity

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Date:   Fri, 7 Oct 2016 01:11:09 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Dietmar Eggemann <dietmar.eggemann@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Wanpeng Li <kernellwp@...il.com>,
        Yuyang Du <yuyang.du@...el.com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
        Paul Turner <pjt@...gle.com>,
        Benjamin Segall <bsegall@...gle.com>
Subject: Re: [PATCH 1/7 v4] sched: factorize attach entity

On 5 October 2016 at 11:38, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
> On 09/26/2016 01:19 PM, Vincent Guittot wrote:
>>
>> Factorize post_init_entity_util_avg and part of attach_task_cfs_rq
>> in one function attach_entity_cfs_rq
>>
>> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
>> ---
>>  kernel/sched/fair.c | 19 +++++++++++--------
>>  1 file changed, 11 insertions(+), 8 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 986c10c..e8ed8d1 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -697,9 +697,7 @@ void init_entity_runnable_average(struct sched_entity
>> *se)
>>  }
>>
>>  static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
>> -static int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool
>> update_freq);
>> -static void update_tg_load_avg(struct cfs_rq *cfs_rq, int force);
>> -static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct
>> sched_entity *se);
>> +static void attach_entity_cfs_rq(struct sched_entity *se);
>>
>>  /*
>>   * With new tasks being created, their initial util_avgs are extrapolated
>> @@ -764,9 +762,7 @@ void post_init_entity_util_avg(struct sched_entity
>> *se)
>>               }
>>       }
>
>
> You now could move the 'u64 now = cfs_rq_clock_task(cfs_rq);' into the
> if condition to handle !fair_sched_class tasks.

yes

>
>> -     update_cfs_rq_load_avg(now, cfs_rq, false);
>> -     attach_entity_load_avg(cfs_rq, se);
>> -     update_tg_load_avg(cfs_rq, false);
>> +     attach_entity_cfs_rq(se);
>>  }
>>
>>  #else /* !CONFIG_SMP */
>> @@ -8501,9 +8497,8 @@ static void detach_task_cfs_rq(struct task_struct
>> *p)
>>       update_tg_load_avg(cfs_rq, false);
>>  }
>>
>> -static void attach_task_cfs_rq(struct task_struct *p)
>> +static void attach_entity_cfs_rq(struct sched_entity *se)
>>  {
>> -     struct sched_entity *se = &p->se;
>>       struct cfs_rq *cfs_rq = cfs_rq_of(se);
>
>
> Both callers of attach_entity_cfs_rq() already use cfs_rq_of(se). You
> could pass it into attach_entity_cfs_rq().

Yes that would make sense

>
>>       u64 now = cfs_rq_clock_task(cfs_rq);
>> @@ -8519,6 +8514,14 @@ static void attach_task_cfs_rq(struct task_struct
>> *p)
>
>
> The old comment /* Synchronize task ... */ should be changed to /*
> Synchronize entity ... */

yes

>
>>       update_cfs_rq_load_avg(now, cfs_rq, false);
>>       attach_entity_load_avg(cfs_rq, se);
>>       update_tg_load_avg(cfs_rq, false);
>> +}
>> +
>> +static void attach_task_cfs_rq(struct task_struct *p)
>> +{
>> +     struct sched_entity *se = &p->se;
>> +     struct cfs_rq *cfs_rq = cfs_rq_of(se);
>> +
>> +     attach_entity_cfs_rq(se);
>>
>>       if (!vruntime_normalized(p))
>>               se->vruntime += cfs_rq->min_vruntime;
>>
>
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