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

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Date:   Wed, 5 Oct 2016 10:38:25 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>,
        <peterz@...radead.org>, <mingo@...nel.org>,
        <linux-kernel@...r.kernel.org>, <kernellwp@...il.com>
CC:     <yuyang.du@...el.com>, <Morten.Rasmussen@....com>,
        <linaro-kernel@...ts.linaro.org>, <pjt@...gle.com>,
        <bsegall@...gle.com>
Subject: Re: [PATCH 1/7 v4] sched: factorize attach entity

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.

> -     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().

>       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 ... */

>       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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