Messages in this thread | | | Date | Mon, 23 Mar 2009 11:38:21 +0100 | From | Pavel Machek <> | Subject | Re: nonboot cpu on SMP suspend |
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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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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