linux-kernel - Re: [RFC PATCH 2/2] sched: idle: IRQ based next prediction for idle period

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Date:	Tue, 12 Jan 2016 15:16:44 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	peterz@...radead.org, rafael@...nel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, nicolas.pitre@...aro.org,
	vincent.guittot@...aro.org
Subject: Re: [RFC PATCH 2/2] sched: idle: IRQ based next prediction for idle
 period

On 01/12/2016 02:42 PM, Thomas Gleixner wrote:
> On Tue, 12 Jan 2016, Daniel Lezcano wrote:
>> On 01/08/2016 04:43 PM, Thomas Gleixner wrote:
>>>> +	/*
>>>> +	 * Register the setup/free irq callbacks, so new interrupt or
>>>> +	 * freed interrupt will update their tracking.
>>>> +	 */
>>>> +	ret = register_irq_timings(&irqt_ops);
>>>> +	if (ret) {
>>>> +		pr_err("Failed to register timings ops\n");
>>>> +		return ret;
>>>> +	}
>>>
>>> So that stuff is installed unconditionally. Is it used unconditionally as
>>> well?
>>
>> Sorry, I am not sure to understand your question. If the kernel is compiled
>> with CONFIG_CPU_IDLE_GOV_SCHED=y, this code is enabled and use the irq
>> timings. The condition comes from the compilation option.
>
> The question is whether the option also activates that thing or is there still
> some /sys/whatever/idlegov magic where you can (de)select it.

Yes, in the next patches of the series I did not send, we can switch to 
the cpuidle's governor framework or idle-sched. I will look at how to 
disable it when switching to the cpuidle's governors.

Thanks

   -- Daniel


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