linux-kernel - Re: [PATCH v2 2/2] sched/fair, cpufreq: Introduce 'runnable boosting'

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 12 May 2023 13:22:29 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Dietmar Eggemann <dietmar.eggemann@....com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Qais Yousef <qyousef@...alina.io>,
        Kajetan Puchalski <kajetan.puchalski@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Vincent Donnefort <vdonnefort@...gle.com>,
        Quentin Perret <qperret@...gle.com>,
        Abhijeet Dharmapurikar <adharmap@...cinc.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] sched/fair, cpufreq: Introduce 'runnable boosting'

On Fri, May 12, 2023 at 12:10:29PM +0200, Dietmar Eggemann wrote:

> -static unsigned long cpu_util(int cpu, struct task_struct *p, int dst_cpu)
> +static unsigned long
> +cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
>  {
>  	struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
>  	unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
> +	unsigned long runnable;
> +
> +	runnable = boost ? READ_ONCE(cfs_rq->avg.runnable_avg) : 0;
> +	util = max(util, runnable);
>  
	if (boost)
		util = max(util, READ_ONCE(cfs_rq->avg.runnable_avg));


> @@ -7239,9 +7246,9 @@ static unsigned long cpu_util(int cpu, struct task_struct *p, int dst_cpu)
>   *
>   * Return: (Estimated) utilization for the specified CPU.
>   */

Given that cpu_util() is the base function should this comment move
there?

> -unsigned long cpu_util_cfs(int cpu)
> +unsigned long cpu_util_cfs(int cpu, int boost)
>  {
> -	return cpu_util(cpu, NULL, -1);
> +	return cpu_util(cpu, NULL, -1, boost);
>  }

AFAICT the @boost argument is always a constant (0 or 1). Would it not
make more sense to simply add:

unsigned long cpu_util_cfs_boost(int cpu)
{
	return cpu_util(cpu, NULL, -1, 1);
}

and use that in the few sites that actually need it?