[v7 PATCH 0/7]: cpuidle/x86/POWER: Cleanup idle power management code in x86, cleanup drivers/cpuidle/cpuidle.c and introduce cpuidle to POWER.
svaidy at linux.vnet.ibm.com
Wed Oct 7 22:26:48 EST 2009
* Peter Zijlstra <a.p.zijlstra at chello.nl> [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?
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
As far as powerpc is concerned, we can work with a single global
registration. However we would like to have the same interface across
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
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