From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shreyas B Prabhu <shreyas@linux.vnet.ibm.com>
Subject: Re: [PATCH V3 2/2] sched: idle: IRQ based next prediction for idle
 period
Date: Tue, 23 Feb 2016 15:38:16 +0530
Message-ID: <56CC2F90.4040008@linux.vnet.ibm.com>
References: <1455637383-14412-1-git-send-email-daniel.lezcano@linaro.org> <1455637383-14412-2-git-send-email-daniel.lezcano@linaro.org> <56CB22F5.8010808@linux.vnet.ibm.com> <56CB455C.3050701@linaro.org>
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To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: tglx@linutronix.de, peterz@infradead.org, rafael@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, nicolas.pitre@linaro.org, vincent.guittot@linaro.org
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On 02/22/2016 10:59 PM, Daniel Lezcano wrote:
> On 02/22/2016 04:02 PM, Shreyas B Prabhu wrote:
>> Hi Daniel,
>>
>> On 02/16/2016 09:13 PM, Daniel Lezcano wrote:
>>> +
>>> +/**
>>> + * sched_idle_next_wakeup - Predict the next wakeup on the current cpu
>>> + *
>>> + * The next event on the cpu is based on a statistic approach of the
>>> + * interrupt events and the timer deterministic value. From the timer
>>> + * or the irqs, we return the one expected to occur first.
>>> + *
>>> + * Returns the expected remaining idle time before being woken up by
>>> + * an interruption.
>>> + */
>>> +s64 sched_idle_next_wakeup(void)
>>> +{
>>> +    s64 next_timer = ktime_to_us(tick_nohz_get_sleep_length());
>>> +    s64 next_irq = next_irq_event();
>>
>> Since next_irq_event() uses RCU and we are in idle this should probably
>> be wrapped in RCU_NONIDLE().
> 
> That is a good point but the function is not supposed to be called in
> the rcu_idle_enter/rcu_idle_exit section which is inside
> cpuidle_idle_call().
> 
> 
Right. My bad.