From: Pavel Machek <pavel@ucw.cz>
To: Li Yang <leoli@freescale.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: nonboot cpu on SMP suspend
Date: Mon, 23 Mar 2009 11:38:21 +0100 [thread overview]
Message-ID: <20090323103821.GC17681@elf.ucw.cz> (raw)
In-Reply-To: <2a27d3730903230015h6cc320bek423764eb496d6b30@mail.gmail.com>
On Mon 2009-03-23 15:15:57, Li Yang wrote:
> On Sat, Mar 21, 2009 at 2:58 AM, Pavel Machek <pavel@ucw.cz> wrote:
> > On Wed 2009-03-18 14:25:32, Li Yang wrote:
> >> Hi all,
> >>
> >> I'm curious why we need to un-plug all the nonboot cpus before suspend
> >> and start them all over again after the suspend(ACPI sleep)? I mean
> >> if we can bring the booting cpu back to the exact state as before
> >> suspend, why can't we just do the same for non-booting cpus? And that
> >> will be much faster. Any thought? Thanks.
> >
> > Why do you think it will be faster?
>
> _cpu_down() and _cpu_up() are surely complex functions, involving
> work_queues and synchronization between boot cpu and non-boot cpu. On
> the contrary, to bring the cpu back to previous state is much simpler.
> For standby state, you barely need to do anything. For mem state,
> you only need to restore the registers and states of the CPU.
Feel free to cook up a patch.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
prev parent reply other threads:[~2009-03-23 10:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-18 6:25 Li Yang
2009-03-18 23:00 ` Rafael J. Wysocki
2009-03-19 7:04 ` chen gong
2009-03-19 7:18 ` Li Yang
2009-03-19 12:30 ` Rafael J. Wysocki
2009-03-20 18:58 ` Pavel Machek
2009-03-23 7:15 ` Li Yang
2009-03-23 10:38 ` Pavel Machek [this message]
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