* Vaidy <svaidy@xxxxxxxxxxxxxxxxxx> [2009-10-07 16:56:48]: > * Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> [2009-10-06 20:04:39]: > > > On Tue, 2009-10-06 at 22:05 +0530, Arun R Bharadwaj wrote: > > > > > Also, the per-cpu nature of registration/unregistration of cpuidle > > > has been maintained as ACPI needs this. > > > > Right, so can't we ditch that and have acpi default to the lowest common > > C-state and warn when various cpus report different C-states? > > Hi Peter, > > As Arjan mentioned previously, the per-cpu registration has to stay > for x86 for now due to legacy ACPI compatibility. Breaking that may > break lot of existing users and we do not have a clean fallback > method. > > As far as powerpc is concerned, we can work with a single global > registration. However we would like to have the same interface across > different archs. > > With the new re-factoring (v7), Arun has killed most of the list > traversal and linking between various cpu's cpuidle_driver structures. > Now we have a per-cpu stack of registered devices and we lookup the > structs using online cpumasks. The cpuidle_driver structure has list > of idle routing pointers (struct cpuidle_state) and rest of it is > statistics that needs to be maintained at a per-cpu level anyway. All > that is duplicated here is the array of idle routines (struct > cpuidle_state) on each cpu. > > The objective of the refactoring is to have a single common idle > routine management framework (remove pm_idle) and we have it done > through cpuidle registration framework. We can incrementally remove > the per-cpu registration later easily by splitting the cpuidle_driver > structure. > Yes, incremental refactoring makes the most sense from the do not break as you refactor point of view. -- Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
