linux-kernel - Re: [PATCH v6 3/3] sched/fair: Combine EAS check with overutilized access

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Date: Tue, 26 Mar 2024 08:58:28 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Shrikanth Hegde <sshegde@...ux.ibm.com>
Cc: peterz@...radead.org, vincent.guittot@...aro.org, yu.c.chen@...el.com,
	dietmar.eggemann@....com, linux-kernel@...r.kernel.org,
	nysal@...ux.ibm.com, aboorvad@...ux.ibm.com, srikar@...ux.ibm.com,
	vschneid@...hat.com, pierre.gondois@....com, qyousef@...alina.io
Subject: Re: [PATCH v6 3/3] sched/fair: Combine EAS check with overutilized
 access


* Shrikanth Hegde <sshegde@...ux.ibm.com> wrote:

>  /*
> - * Ensure that caller can do EAS. overutilized value
> - * make sense only if EAS is enabled
> + * overutilized value make sense only if EAS is enabled
>   */
> -static inline int is_rd_overutilized(struct root_domain *rd)
> +static inline int is_rd_not_overutilized(struct root_domain *rd)
>  {
> -	return READ_ONCE(rd->overutilized);
> +	return sched_energy_enabled() && !READ_ONCE(rd->overutilized);
>  }

While adding the sched_energy_enabled() condition looks OK, the _not prefix 
This is silly: putting logical operators into functions names is far less 
readable than a !fn()...

> -	if (!is_rd_overutilized(rq->rd) && cpu_overutilized(rq->cpu))
> +	if (is_rd_not_overutilized(rq->rd) && cpu_overutilized(rq->cpu))

Especially since we already have cpu_overutilized(). It's far more coherent 
to have the same basic attribute functions and put any negation into 
*actual* logical operators.

Thanks,

	Ingo