On Fri, 2009-08-28 at 15:30 +0530, Gautham R Shenoy wrote: > Hi, > > This is the version 2 of the patch series to provide a cpu-offline framework > that enables the administrators choose the state the offline CPU must be put > into when multiple such states are exposed by the underlying architecture. > > Version 1 of the Patch can be found here: > http://lkml.org/lkml/2009/8/6/236 > > The patch-series exposes the following sysfs tunables to > allow the system-adminstrator to choose the state of a CPU: > > To query the available hotplug states, one needs to read the sysfs tunable: > /sys/devices/system/cpu/cpu<number>/available_hotplug_states > To query or set the current state, on needs to read/write the sysfs tunable: > /sys/devices/system/cpu/cpu<number>/current_states > > The patchset ensures that the writes to the "current_state" sysfs file are > serialized against the writes to the "online" file. > > This patchset also contains the offline state driver implemented for > pSeries. For pSeries, we define three available_hotplug_states. They are: > > online: The processor is online. > > deallocate: This is the the default behaviour when the cpu is offlined > even in the absense of this driver. The CPU would call make an > rtas_stop_self() call and hand over the CPU back to the resource pool, > thereby effectively deallocating that vCPU from the LPAR. > NOTE: This would result in a configuration change to the LPAR > which is visible to the outside world. > > deactivate: This cedes the vCPU to the hypervisor which > in turn can put the vCPU time to the best use. > NOTE: This option DOES NOT result in a configuration change > and the vCPU would be still entitled to the LPAR to which it earlier > belong to. > > Awaiting your feedback.
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. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev