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    Subject[PATCH v2 0/1] Touch kernel watchdog with sched count
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    The main purpose of kernel watchdog is to test whether scheduler can
    still schedule tasks on a cpu. In order to reduce latency / jitter
    from periodically invoking watchdog reset in thread context, we can
    simply test if pick_next_task can run. This is done by forcing resched
    and checking rq->sched_count. Compared to actually resetting watchdog
    from cpu stop / migration threads, we lose coverage on: a migration
    thread actually get picked and we actually context switch to the
    migration thread. These steps are unlikely to silently fail. The
    change would provide nearly the same level of protection with less
    overhead.

    With this patch we can still switch back to the old method with the
    boot option watchdog_touch_with_thread. However code for the old
    method can be completely removed in the future.


    v2:
    - Use sched_count instead of having sched calling into watchdog code
    - Remove the sysctl and add a boot option, which can be removed later
    - Changed the subject line



    Xi Wang (1):
    sched: watchdog: Touch kernel watchdog with sched count

    include/linux/sched.h | 4 ++++
    kernel/sched/core.c | 23 ++++++++++++++++++++--
    kernel/sched/sched.h | 6 +++++-
    kernel/watchdog.c | 44 +++++++++++++++++++++++++++++++++++++------
    4 files changed, 68 insertions(+), 9 deletions(-)

    --
    2.29.0.rc1.297.gfa9743e501-goog

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