Messages in this thread | | | Date | Fri, 30 Jul 2021 17:18:27 -0300 | From | Marcelo Tosatti <> | Subject | [patch 0/4] extensible prctl task isolation interface and vmstat sync (v2) |
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The logic to disable vmstat worker thread, when entering nohz full, does not cover all scenarios. For example, it is possible for the following to happen:
1) enter nohz_full, which calls refresh_cpu_vm_stats, syncing the stats. 2) app runs mlock, which increases counters for mlock'ed pages. 3) start -RT loop
Since refresh_cpu_vm_stats from nohz_full logic can happen _before_ the mlock, vmstat shepherd can restart vmstat worker thread on the CPU in question.
To fix this, add task isolation prctl interface to quiesce deferred actions when returning to userspace.
The patchset is based on ideas and code from the task isolation patchset from Alex Belits: https://lwn.net/Articles/816298/
Please refer to Documentation/userspace-api/task_isolation.rst (patch 1) for details.
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v2:
- Finer-grained control of quiescing (Frederic Weisbecker / Nicolas Saenz).
- Avoid potential regressions by allowing applications to use ISOL_F_QUIESCE_DEFMASK (whose default value is configurable in /sys/). (Nitesh Lal / Nicolas Saenz).
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