linux-kernel - Re: [PATCH 58/76] idle, x86: Allow off-lined CPU to enter deeper C states

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Message-ID: <4F79EBAA.7040602@amd.com>
Date:	Mon, 2 Apr 2012 14:10:50 -0400
From:	Boris Ostrovsky <boris.ostrovsky@....com>
To:	Tony Luck <tony.luck@...il.com>
CC:	Len Brown <lenb@...nel.org>, <linux-acpi@...r.kernel.org>,
	<linux-pm@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>, Len Brown <len.brown@...el.com>
Subject: Re: [PATCH 58/76] idle, x86: Allow off-lined CPU to enter deeper
 C states

On 04/02/12 14:02, Tony Luck wrote:
>> x86 halt() causes processor to go to C1 state (which is often not the
>> deepest). But other than that it seems similar to what you are describing.
>
> OK - then Konrad's suggestion of using "safe_halt()" here rather than
> "halt()" would work for ia64.

I originally didn't want to use safe_halt() because the CPU will wake up 
on an unmasked HW interrupt unlike halt(). But I guess we are not 
supposed to get any such interrupts when we are off-lining a CPU so 
safe_halt() should be OK.

Thanks.
-boris

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