Instead of periodically resetting watchdogs from thread context, this patch simply forces resched and checks rq->sched_count. Watchdog is reset if the sched count increases. If the same thread is picked by pick_next_task during resched, there is no context switch.
With the new method we lose coverage on: a migration/n thread actually gets picked and we actually context switch to the migration/n thread. These steps are unlikely to silently fail. The change would provide nearly the same level of protection with less latency / jitter. v3: - Removed the old method and boot option - Still need to check resched 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 | 47 +++++++++++++------------------------------ 4 files changed, 44 insertions(+), 36 deletions(-) -- 2.29.0.rc2.309.g374f81d7ae-goog
