Messages in this thread | | | Date | Thu, 01 Jul 2021 18:03:36 -0300 | From | Marcelo Tosatti <> | Subject | [patch 0/5] optionally sync per-CPU vmstats counter on return to userspace |
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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, optionally sync the vmstat counters when returning from userspace, controllable by a new "vmstat_sync" isolcpus flags (default off).
See individual patches for details.
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