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    Subject[PATCH v3 0/3] cpu: pseries: Cpu offline states framework

    **** 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

    Changes from Version 2:(can be found here:
    - 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:
    To query or set the current state, on needs to read/write the sysfs tunable:

    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

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      Last update: 2009-09-15 14:11    [W:0.045 / U:6.136 seconds]
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