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SubjectRE: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi
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On Tue, 2012-06-05 at 21:43 +0200, Thomas Gleixner wrote:
> Vs. the interrupt/timer/other crap madness:
>
> - We really don't want to have an interrupt balancer in the kernel
> again, but we need a mechanism to prevent the user space balancer
> trainwreck from ruining the power saving party.

What's wrong with having an interrupt balancer tied to the scheduler
which optimistically tries to avoid interrupting nohz/isolated/idle
cpus?

> - The timer issue is mostly solved by the existing nohz stuff
> (plus/minus the few bugs in there).

Its not.. if you create an isolated domain there's no way to expel
existing timers from there.

> - The other details (silly IPIs) and cross CPU timer arming) are way
> easier to solve by a proper prohibitive state than by chasing that
> nonsense all over the tree forever.

But we need to solve all that without a prohibitibe state anyway for the
isolation stuff to be useful.




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