Re: nonboot cpu on SMP suspend

[Pavel Machek]

On Mon 2009-03-23 15:15:57, Li Yang wrote:
> On Sat, Mar 21, 2009 at 2:58 AM, Pavel Machek <pavel@xxxxxx> 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
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