Re: smp: Start up non-boot CPUs asynchronously

[Arjan van de Ven]

On Tue, 31 Jan 2012 13:52:32 +0100
Ingo Molnar <mingo@xxxxxxx> 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
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