linux-kernel - Re: [PATCH] cpufreq: schedutil: fix equation in comment

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Message-ID: <20190805045442.3pnaawo4nlrieoie@vireshk-i7>
Date:   Mon, 5 Aug 2019 10:24:42 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Qais Yousef <qais.yousef@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Ingo Molnar <mingo@...hat.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: schedutil: fix equation in comment

On 02-08-19, 11:46, Qais Yousef wrote:
> scale_irq_capacity() call in schedutil_cpu_util() does
> 
> 	util *= (max - irq)
> 	util /= max
> 
> But the comment says
> 
> 	util *= (1 - irq)
> 	util /= max
> 
> Fix the comment to match what the scaling function does.
> 
> Signed-off-by: Qais Yousef <qais.yousef@....com>
> ---
>  kernel/sched/cpufreq_schedutil.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 636ca6f88c8e..e127d89d5974 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -259,9 +259,9 @@ unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
>  	 * irq metric. Because IRQ/steal time is hidden from the task clock we
>  	 * need to scale the task numbers:
>  	 *
> -	 *              1 - irq
> -	 *   U' = irq + ------- * U
> -	 *                max
> +	 *              max - irq
> +	 *   U' = irq + --------- * U
> +	 *                 max
>  	 */
>  	util = scale_irq_capacity(util, irq, max);
>  	util += irq;

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh