linux-kernel - Re: [RFC PATCH 1/3] sched/fair: Aggregate task utilization only on root cfs

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Date:	Thu, 2 Jun 2016 17:11:34 +0100
From:	Juri Lelli <juri.lelli@....com>
To:	Dietmar Eggemann <dietmar.eggemann@....com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Ben Segall <bsegall@...gle.com>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Yuyang Du <yuyang.du@...el.com>
Subject: Re: [RFC PATCH 1/3] sched/fair: Aggregate task utilization only on
 root cfs_rq

On 02/06/16 16:53, Dietmar Eggemann wrote:
> On 02/06/16 10:23, Juri Lelli wrote:
> 
> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >> index 218f8e83db73..212becd3708f 100644
> >> --- a/kernel/sched/fair.c
> >> +++ b/kernel/sched/fair.c
> >> @@ -2705,6 +2705,7 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> >>  	u32 contrib;
> >>  	unsigned int delta_w, scaled_delta_w, decayed = 0;
> >>  	unsigned long scale_freq, scale_cpu;
> >> +	int update_util = 0;
> >>  
> >>  	delta = now - sa->last_update_time;
> >>  	/*
> >> @@ -2725,6 +2726,12 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
> >>  		return 0;
> >>  	sa->last_update_time = now;
> >>  
> >> +	if (cfs_rq) {
> >> +		if (&rq_of(cfs_rq)->cfs == cfs_rq)
> > 
> > Maybe we can wrap this sort of checks in a static inline improving
> > readability?
> 
> Something like this?
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 218f8e83db73..01b0fa689ef9 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -251,6 +251,18 @@ static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
>         return cfs_rq->rq;
>  }
>  
> +/* cfs_rq "owned" by the root task group */
> +static inline struct cfs_rq *root_rq_of(struct cfs_rq *cfs_rq)
> +{
> +       return &rq_of(cfs_rq)->cfs;
> +}
> +
> +/* Is this cfs_rq "owned" by the root task group ? */
> +static inline bool rq_is_root(struct cfs_rq *cfs_rq)
> +{
> +       return root_rq_of(cfs_rq) == cfs_rq;
> +}
> +
>  /* An entity is a task if it doesn't "own" a runqueue */
>  #define entity_is_task(se)     (!se->my_q)
>  
> @@ -376,6 +388,16 @@ static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
>         return container_of(cfs_rq, struct rq, cfs);
>  }
>  
> +static inline struct cfs_rq *root_rq_of(struct cfs_rq *cfs_rq)
> +{
> +       return cfs_rq;
> +}
> +
> +static inline bool rq_is_root(struct cfs_rq *cfs_rq)
> +{
> +       return true;
> +}
> +
>  #define entity_is_task(se)     1
> 

Looks good to me.

Thanks,

- Juri