linux-kernel - Re: [PATCH V3] PM / EM: Micro optimization in em_cpu

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Message-ID: <f98e3547-6896-5bd7-e748-57d1bba377c3@arm.com>
Date:   Tue, 24 Nov 2020 15:59:40 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Pavankumar Kondeti <pkondeti@...eaurora.org>,
        linux-kernel@...r.kernel.org
Cc:     Lukasz Luba <lukasz.luba@....com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Quentin Perret <qperret@...gle.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: Re: [PATCH V3] PM / EM: Micro optimization in em_cpu_energy

On 23/11/2020 11:35, Pavankumar Kondeti wrote:
> When the sum of the utilization of CPUs in a performance domain is
> zero, return the energy as 0 without doing any computations.
> 
> Signed-off-by: Pavankumar Kondeti <pkondeti@...eaurora.org>
> ---
> V3: %s/power/performance as corrected by Quentin
> V2: Fixed the function name in the commit message.
> 
>  include/linux/energy_model.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> index b67a51c..8810f1f 100644
> --- a/include/linux/energy_model.h
> +++ b/include/linux/energy_model.h
> @@ -103,6 +103,9 @@ static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
>  	struct em_perf_state *ps;
>  	int i, cpu;
>  
> +	if (!sum_util)
> +		return 0;
> +
>  	/*
>  	 * In order to predict the performance state, map the utilization of
>  	 * the most utilized CPU of the performance domain to a requested


LGTM.

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>