On Wed, 2009-09-02 at 07:33 +0200, Peter Zijlstra wrote: > > I'm still thinking this is a bad idea. > > The OS should only know about online/offline. > > Use the hypervisor interface to deal with the cpu once its offline. > > That is, I think this interface you propose is a layering violation. > I don't quite follow your logic here. This is useful for more than just hypervisors. For example, take the HV out of the picture for a moment and imagine that the HW has the ability to offline CPU in various power levels, with varying latencies to bring them back.
For example, the HW can put them in some low power state where they can be re-plugged quickly, or can shutdown entire power planes completely, possibly allowing physical hotplug, but that takes much longer to bring them back into the pool. In any case, regarding the pseries case, this is how our hypervisor works and I don't think we can change it, other than by always going into the "cede" function and having some weird separate interface in the arch to then whack them into some different state. Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
