RE: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait ornmi

[Luck, Tony]

> Like what? Offline is nothing more than a C state on x86. 

Offline is a bigger hammer than idle.

When a core is idle it may take an interrupt which wakes it up to use power.
The scheduler may assign a process to run on it, which will wake it up to use power.

When a core is offline we take extra steps (re-routing interrupts, telling the
scheduler it is not available for work) to make sure it STAYS in that low
power state.

-Tony
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