linux-kernel - Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal

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Date:   Thu, 20 Feb 2020 16:04:30 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com, rostedt@...dmis.org,
        bsegall@...gle.com, mgorman@...e.de, linux-kernel@...r.kernel.org
Cc:     pauld@...hat.com, parth@...ux.ibm.com, valentin.schneider@....com,
        hdanton@...a.com
Subject: Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal

On 19/02/2020 13:55, Vincent Guittot wrote:
> Now that runnable_load_avg has been removed, we can replace it by a new
> signal that will highlight the runnable pressure on a cfs_rq. This signal
> track the waiting time of tasks on rq and can help to better define the
> state of rqs.
> 
> At now, only util_avg is used to define the state of a rq:
>   A rq with more that around 80% of utilization and more than 1 tasks is
>   considered as overloaded.

Don't we make the distinction of overutilized and overloaded?

update_sg_lb_stats(), SG_OVERUTILIZED and SG_OVERLOAD

[...]

> @@ -310,13 +325,14 @@ int __update_load_avg_cfs_rq(u64 now, struct cfs_rq *cfs_rq)
>   *   util_sum = cpu_scale * load_sum
>   *   runnable_sum = util_sum
>   *
> - *   load_avg is not supported and meaningless.
> + *   load_avg and runnable_load_avg are not supported and meaningless.

Nit pick:

s/runnable_load_avg/runnable_avg

[...]

> + *   load_avg and runnable_load_avg are not supported and meaningless.
>   *
>   */
>  
>  int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)

[...]

> - *   load_avg is not supported and meaningless.
> + *   load_avg and runnable_load_avg are not supported and meaningless.
>   *
>   */
>  
> @@ -389,9 +406,11 @@ int update_irq_load_avg(struct rq *rq, u64 running)

[...]