> > I was trying to figure out how difficult it would be to just bring Pxx states to > > the Xen hypervisor using the existing ACPI interfaces. And while it did not pass > > all the _Pxx states (seems that all the _PCT, _PSS, _PSD, _PPC flags need to > > be enabled in the hypercall to make this work), it demonstrates what I had in > > mind. .. snip.. > > /* TODO: Under Xen, the C-states information is not present. > > * Figure out why. */ > > it's possible related to this long thread: > > http://lists.xen.org/archives/html/xen-devel/2011-08/msg00511.html > > IOW, Xen doesn't export mwait capability to dom0, which impacts _PDC setting. > Final solution is to have a para-virtualized PDC call for that. Aaah. Let me play with that a bit. Thanks for the pointer. .. snip.. > the prerequisites for this module to work correctly, is that dom0 has the right > configurations to have all necessary Cx/Px information ready before this > module is loaded. That may mean enabling full CONFIG_CPU_IDLE and CONFIG_CPUFREQ, Right. > which in current form may add some negative impact, e.g. dom0 will try to control > Px/Cx to conflict with Xen. So some tweaks may be required in that part. Yup. Hadn't even looked at the cpufreq tries to do yet. > > given our purpose now, is to come up a cleaner approach which tolerate some > assumptions (e.g. #VCPU of dom0 == #PCPU), there's another option following this > trend (perhaps compensate your idea). We can register a Xen-cpuidle and > xen-cpufreq driver to current Linux cpuidle and cpufreq framework, which plays > mainly two roles: > - a dummy driver to prevent dom0 touching actual Px/Cx > - parse ACPI Cx/Px information to Xen, in a similar way you did above Yeah, I like where you are heading. > > there may have some other trickiness, but the majority code will be self-contained. <nods> > > Thanks > Kevin > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
