Messages in this thread | | | Subject | Re: [PATCH V5 2/2] tracing, perf : add cpu hotplug trace events | From | Peter Zijlstra <> | Date | Thu, 24 Feb 2011 21:49:49 +0100 |
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On Thu, 2011-02-24 at 15:40 -0500, Nicolas Pitre wrote: > On Thu, 24 Feb 2011, Peter Zijlstra wrote: > > > On Thu, 2011-02-24 at 15:24 -0500, Nicolas Pitre wrote: > > > > > Most SMP ARM processors are going to use it soon. Powering down idle > > > cores provides substantial power saving. > > > > And why can't regular idle paths be used? CPU hotplug is a massively > > expensive operation. > > The idle path assumes that the CPU state is preserved.
Not much of it,
> We're talking > about cores completely going down with power pulled beneath them and > eventually rebooted dynamically here.
I think you can get away with actually pulling the power and re-initing the cpu to idle from the idle path and the rest of the kernel not caring.
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