Messages in this thread | | | Date | Wed, 12 Oct 2022 13:41:01 +0100 | From | Aaron Tomlin <> | Subject | Re: [PATCH v8 5/5] tick/sched: Ensure quiet_vmstat() is called when the idle tick was stopped too |
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> Given work canceled because per-CPU pages can be freed remotely from > housekeeping CPUs (see patch 3/5), what is added here is not needed.
Hi Hillf,
Firstly, apologies for the delay!
The concern is to ensure CPU-specific vmstat counters are reset and folded into NUMA node and zone specific and global counters too before entering idle. It is necessary to invoke quiet_vmstat() on return to idle even if the scheduling-clock tick has been previously stopped. Please refer to the complete scenario I described again.
If I understand correctly, indeed the remote drain/or free of zone CPU-specific pages can be initiated by a "housekeeping" CPU i.e. refresh_cpu_vm_stats(true) via a worker thread/or kworker, yet the actual free will only occur when the nohz_full CPU exits idle code and calls schedule_idle().
Kind regards,
-- Aaron Tomlin
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