linux-kernel - Re: [PATCH 5/6] intel_idle: Add ->enter

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Message-ID: <20150212132643.GY23123@twins.programming.kicks-ass.net>
Date:	Thu, 12 Feb 2015 14:26:43 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Alan Cox <alan@...ux.intel.com>,
	"Li, Aubrey" <aubrey.li@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Kristen Carlson Accardi <kristen@...ux.intel.com>,
	John Stultz <john.stultz@...aro.org>,
	Len Brown <len.brown@...el.com>
Subject: Re: [PATCH 5/6] intel_idle: Add ->enter_freeze callbacks

On Wed, Feb 11, 2015 at 05:04:17AM +0100, Rafael J. Wysocki wrote:
> @@ -131,28 +133,32 @@ static struct cpuidle_state nehalem_csta
>  		.flags = MWAIT2flg(0x00),
>  		.exit_latency = 3,
>  		.target_residency = 6,
> -		.enter = &intel_idle },
> +		.enter = &intel_idle,
> +		.enter_freeze = intel_idle_freeze, },
>  	{
>  		.name = "C1E-NHM",
>  		.desc = "MWAIT 0x01",
>  		.flags = MWAIT2flg(0x01),
>  		.exit_latency = 10,
>  		.target_residency = 20,
> -		.enter = &intel_idle },
> +		.enter = &intel_idle,
> +		.enter_freeze = intel_idle_freeze, },
>  	{
>  		.name = "C3-NHM",
>  		.desc = "MWAIT 0x10",
>  		.flags = MWAIT2flg(0x10) | CPUIDLE_FLAG_TLB_FLUSHED,
>  		.exit_latency = 20,
>  		.target_residency = 80,
> -		.enter = &intel_idle },
> +		.enter = &intel_idle,
> +		.enter_freeze = intel_idle_freeze, },
>  	{
>  		.name = "C6-NHM",
>  		.desc = "MWAIT 0x20",
>  		.flags = MWAIT2flg(0x20) | CPUIDLE_FLAG_TLB_FLUSHED,
>  		.exit_latency = 200,
>  		.target_residency = 800,
> -		.enter = &intel_idle },
> +		.enter = &intel_idle,
> +		.enter_freeze = intel_idle_freeze, },
>  	{
>  		.enter = NULL }
>  };

Why bother with enter_freeze() for any but the deepest state (C6 in this
case)?

Also, should we ignore things like intel_idle.max_cstate for this
selection?
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