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SubjectRe: smp: Start up non-boot CPUs asynchronously
On Tue, 31 Jan 2012 13:52:32 +0100
Ingo Molnar <mingo@elte.hu> wrote:
>
> The real fix would be to make the init code depend less on each
> other, i.e. have less hotplug lock dependencies. Or, if it's
> such a hot lock for a good reason, why does spinning on it slow
> down the boot process? It really shouldnt.

by inspection, anything that calls get_online_cpus()/put_online_cpus()
will block while a CPU is coming up. This is used in things like
kmem_cache_create()... which is used about everywhere.
(there's various other places... more or less it's a requirement
for using the for_each_online_cpu() api correctly)



--
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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