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    Subject[PATCH v2 0/4] Extending NMI watchdog during LPM
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    When a partition is transferred, once it arrives at the destination node,
    the partition is active but much of its memory must be transferred from the
    start node.

    It depends on the activity in the partition, but the more CPU the partition
    has, the more memory to be transferred is likely to be. This causes latency
    when accessing pages that need to be transferred, and often, for large
    partitions, it triggers the NMI watchdog.

    The NMI watchdog causes the CPU stack to dump where it appears to be
    stuck. In this case, it does not bring much information since it can happen
    during any memory access of the kernel.

    In addition, the NMI interrupt mechanism is not secure and can generate a
    dump system in the event that the interruption is taken while MSR[RI]=0.

    Depending on the LPAR size and load, it may be interesting to extend the
    NMI watchdog timer during the LPM.

    That's configurable through sysctl with the new introduced variable
    (specific to powerpc) lpm_nmi_watchdog_factor. This value represents the
    percentage added to watchdog_tresh to set the NMI watchdog timeout during a
    LPM.

    Changes in v2:
    - introduce a timer factor.

    v1:
    [PATCH 0/2] Disabling NMI watchdog during LPM's memory transfer
    https://lore.kernel.org/linuxppc-dev/20220601155315.35109-1-ldufour@linux.ibm.com/#r

    Laurent Dufour (4):
    powerpc/mobility: Wait for memory transfer to complete
    watchdog: export watchdog_mutex and lockup_detector_reconfigure
    powerpc/watchdog: introduce a LPM factor
    pseries/mobility: Set NMI watchdog factor during LPM

    Documentation/admin-guide/sysctl/kernel.rst | 12 +++
    arch/powerpc/include/asm/nmi.h | 2 +
    arch/powerpc/kernel/watchdog.c | 22 ++++-
    arch/powerpc/platforms/pseries/mobility.c | 90 ++++++++++++++++++++-
    include/linux/nmi.h | 3 +
    kernel/watchdog.c | 6 +-
    6 files changed, 129 insertions(+), 6 deletions(-)

    --
    2.36.1

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