Hi all, This patchset adds a counter, hung_task_detect_count, to track the number of times hung tasks are detected. IHMO, hung tasks are a critical metric. Currently, we detect them by periodically parsing dmesg. However, this method isn't as user-friendly as using a counter. Sometimes, a short-lived issue with NIC or hard drive can quickly decrease the hung_task_warnings to zero. Without warnings, we must directly access the node to ensure that there are no more hung tasks and that the system has recovered. After all, load average alone cannot provide a clear picture. Once this counter is in place, in a high-density deployment pattern, we plan to set hung_task_timeout_secs to a lower number to improve stability, even though this might result in false positives. And then we can set a time-based threshold: if hung tasks last beyond this duration, we will automatically migrate containers to other nodes. Based on past experience, this approach could help avoid many production disruptions. Moreover, just like other important events such as OOM that already have counters, having a dedicated counter for hung tasks makes sense ;) --- Changes since v1 [1] ==================== - hung_task: add detect count for hung tasks - Update the changelog (per Andrew) - Find other folks to CC (per Andrew) [1] https://lore.kernel.org/linux-mm/20241022114736.83285-1-ioworker0@xxxxxxxxx Lance Yang (2): hung_task: add detect count for hung tasks hung_task: add docs for hung_task_detect_count Documentation/admin-guide/sysctl/kernel.rst | 9 +++++++++ kernel/hung_task.c | 18 ++++++++++++++++++ 2 files changed, 27 insertions(+) -- 2.45.2
