Hi, **** RFC not for inclusion ****
This is the version 3 of the patch series to provide a cpu-offline framework that enables the administrators choose the state of a CPU when it is offlined, when multiple such states are exposed by the underlying architecture. Changes from Version 2:(can be found here: http://lkml.org/lkml/2009/8/28/102) - Addressed Andrew Morton's review comments regarding names of global variables, handling of error conditions and documentation of the interfaces. - Implemented a patch to provide helper functions to set the cede latency specifier value in the VPA indicating latency expectation of the guest OS when the vcpu is ceded from a subsequent H_CEDE hypercall. Hypervisor may use this for better energy savings. - Renamed of the cpu-hotplug states. "deallocate" is renamed as "offline" and "deactivate" is renamed as "inactive". 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_hotplug_state The patchset ensures that the writes to the "current_hotplug_state" sysfs file are serialized against the writes to the "online" file. This patchset contains the offline state driver implemented for pSeries. For pSeries, we define three available_hotplug_states. They are: online: The processor is online. offline: 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. inactive: This cedes the vCPU to the hypervisor with a cede latency specifier value 2. 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. Any feedback on the patchset will be immensely valuable. --- Arun R Bharadwaj (1): pSeries: cede latency specifier helper function. Gautham R Shenoy (2): cpu: Implement cpu-offline-state callbacks for pSeries. cpu: Offline state Framework. Documentation/cpu-hotplug.txt | 22 +++ arch/powerpc/include/asm/lppaca.h | 9 + arch/powerpc/platforms/pseries/Makefile | 2 arch/powerpc/platforms/pseries/hotplug-cpu.c | 88 ++++++++++- arch/powerpc/platforms/pseries/offline_driver.c | 148 +++++++++++++++++++ arch/powerpc/platforms/pseries/offline_driver.h | 20 +++ arch/powerpc/platforms/pseries/plpar_wrappers.h | 17 ++ arch/powerpc/platforms/pseries/smp.c | 17 ++ arch/powerpc/xmon/xmon.c | 3 drivers/base/cpu.c | 181 ++++++++++++++++++++++- include/linux/cpu.h | 10 + 11 files changed, 498 insertions(+), 19 deletions(-) create mode 100644 arch/powerpc/platforms/pseries/offline_driver.c create mode 100644 arch/powerpc/platforms/pseries/offline_driver.h -- Thanks and Regards gautham. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
