linux-kernel - Re: [PATCH 2/5] sched: idle: Get the next timer event and pass it the cpuidle framework

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Date:	Mon, 27 Oct 2014 21:53:56 -0400
From:	Len Brown <lenb@...nel.org>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>
Cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Peter Zijlstra <peterz@...radead.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH 2/5] sched: idle: Get the next timer event and pass it the
 cpuidle framework

Reviewed-by: Len Brown <len.brown@...el.com>

On Wed, Oct 22, 2014 at 4:38 PM, Nicolas Pitre <nicolas.pitre@...aro.org> wrote:
> On Mon, 20 Oct 2014, Daniel Lezcano wrote:
>
>> Following the logic of the previous patch, retrieve from the idle task the
>> expected timer sleep duration and pass it to the cpuidle framework.
>>
>> Take the opportunity to remove the unused headers in the menu.c file.
>>
>> This patch does not change the current behavior.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>
> One minor nit below.
>
>> @@ -211,6 +212,12 @@ static void cpu_idle_loop(void)
>>                       latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
>>
>>                       /*
>> +                      * The next timer event in us
>> +                      */
>
> This 3-line comment is redundant. The code is obvious enough on its own.
>
>> +                     next_timer_event = ktime_to_us(
>> +                             tick_nohz_get_sleep_length());
>
> I'd suggest this form for better readability:
>
>                         next_timer_event =
>                                 ktime_to_us(tick_nohz_get_sleep_length());
>
> Other than that...
>
> Acked-by: Nicolas Pitre <nico@...aro.org>
>
>> +
>> +                     /*
>>                        * In poll mode we reenable interrupts and spin.
>>                        *
>>                        * If the latency req is zero, we don't want to
>> @@ -227,7 +234,8 @@ static void cpu_idle_loop(void)
>>                           tick_check_broadcast_expired())
>>                               cpu_idle_poll();
>>                       else
>> -                             cpuidle_idle_call(latency_req);
>> +                             cpuidle_idle_call(latency_req,
>> +                                               next_timer_event);
>>
>>                       arch_cpu_idle_exit();
>>               }
>> --
>> 1.9.1
>>
>>
> --
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-- 
Len Brown, Intel Open Source Technology Center
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