Date: Sat, 14 Aug 2010 09:53:51 -0700
From: Arjan van de Ven <arjan@infradead.org>
To: paulmck@linux.vnet.ibm.com
Cc: Pavel Machek <pavel@ucw.cz>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Felipe Contreras <felipe.contreras@gmail.com>,
        "Ted Ts'o" <tytso@mit.edu>, david@lang.hm,
        Brian Swetland <swetland@google.com>,
        linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        arve@android.com, mjg59@srcf.ucam.org, florian@mickler.org,
        rjw@sisk.pl, stern@rowland.harvard.edu, peterz@infradead.org,
        tglx@linutronix.de, menage@google.com, david-b@pacbell.net,
        James.Bottomley@suse.de, swmike@swm.pp.se, galibert@pobox.com,
        dipankar@in.ibm.com
Subject: Re: Attempted summary of suspend-blockers LKML thread, take three
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On Sat, 14 Aug 2010 08:10:48 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> 
> So once you are down to one CPU, the last CPU shuts the system off,
> itself included?  Or does the last CPU "run" in a deep idle state
> throughout suspend?  (My guess is the former, and I am also curious
> whether the cache SRAMs are powered off, etc.  But figured I should
> ask rather than guessing.)

they tend to go "off".

however I think you're making an assumption that there is a
real difference between a deep idle state and "off"....

For modern x86 hardware, that assumption isn't really valid.
(other than a very very small sram that stores register content in the
idle case)


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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