linux-kernel - Re: [PATCH 3/4] cpuidle/menu: stop seeking deeper idle if current state is too deep

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Message-ID: <57C6B566.70406@linaro.org>
Date:   Wed, 31 Aug 2016 18:45:58 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     open list <linux-kernel@...r.kernel.org>
Cc:     linux-pm@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Rik van Riel <riel@...hat.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 3/4] cpuidle/menu: stop seeking deeper idle if current
 state is too deep

Hi,

Is there any concern on this patch?

Regards
Alex


On 08/25/2016 04:42 PM, Alex Shi wrote:
> The obsolete commit 71abbbf85 want to introduce a dynamic cstates,
> but it was removed for long time. Just left the nonsense deeper cstate
> checking.
> 
> Since all target_residency and exit_latency are going longer in deeper
> idle state, no needs to waste some cpu cycle on useless seeking.
> 
> Signed-off-by: Alex Shi <alex.shi@...aro.org>
> To: linux-kernel@...r.kernel.org
> Cc: linux-pm@...r.kernel.org
> Cc: Ulf Hansson <ulf.hansson@...aro.org>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Alex Shi <alex.shi@...aro.org>
> Cc: Rasmus Villemoes <linux@...musvillemoes.dk>
> Cc: Arjan van de Ven <arjan@...ux.intel.com>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> ---
>  drivers/cpuidle/governors/menu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index 03d38c2..bb58e2a 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -358,9 +358,9 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
>  		if (s->disabled || su->disable)
>  			continue;
>  		if (s->target_residency > data->predicted_us)
> -			continue;
> +			break;
>  		if (s->exit_latency > latency_req)
> -			continue;
> +			break;
>  
>  		data->last_state_idx = i;
>  	}
>