linux-kernel - Re: [PATCH 2/5] sched/fair: rename sum_nr_running to sum_h_nr

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Date:   Fri, 19 Jul 2019 14:51:24 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        quentin.perret@....com, dietmar.eggemann@....com,
        Morten.Rasmussen@....com, pauld@...hat.com
Subject: Re: [PATCH 2/5] sched/fair: rename sum_nr_running to sum_h_nr_running

On Fri, Jul 19, 2019 at 09:58:22AM +0200, Vincent Guittot wrote:
> sum_nr_running will track rq->nr_running task and sum_h_nr_running
> will track cfs->h_nr_running so we can use both to detect when other
> scheduling class are running and preempt CFS.
> 
> There is no functional changes.
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> ---
>  kernel/sched/fair.c | 31 +++++++++++++++++--------------
>  1 file changed, 17 insertions(+), 14 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7a530fd..67f0acd 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7650,6 +7650,7 @@ struct sg_lb_stats {
>  	unsigned long group_capacity;
>  	unsigned long group_util; /* Total utilization of the group */
>  	unsigned int sum_nr_running; /* Nr tasks running in the group */
> +	unsigned int sum_h_nr_running; /* Nr tasks running in the group */
>  	unsigned int idle_cpus;
>  	unsigned int group_weight;
>  	enum group_type group_type;

> @@ -8000,6 +8002,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>  
>  		sgs->group_load += cpu_runnable_load(rq);
>  		sgs->group_util += cpu_util(i);
> +		sgs->sum_h_nr_running += rq->cfs.h_nr_running;
>  		sgs->sum_nr_running += rq->cfs.h_nr_running;
>  
>  		nr_running = rq->nr_running;

Maybe completely remove sum_nr_running in this patch, and introduce it
again later when you change what it counts.