[systemd-devel] oomd wake-up frequency

[Michal Koutný]

Hello.

On Tue, Aug 22, 2023 at 01:59:52PM -0700, Christian Hergert <chergert at redhat.com> wrote:
> The primary thing I see showing up when profiling an idle system is oomd. My
> casual reading through the code would lead me to believe it's waking up a
> CPU every .15 seconds.

That coincides with swap monitoring timer.

> Is there a way we could have this wake up less? My goal here is to iron out
> all the little things which are causing energy drain when idle.

Do you have any "Swap Monitored CGroups:" in output of `oomctl dump`?

I think the loop's event source could be disabled when no cgroups
require swap monitoring [1] (and enabled lazily when such are
configured). 

Not sure whether/how much SWAP_INTERVAL_USEC could be increased to
retain responsiveness.

HTT,
Michal

[1] https://github.com/systemd/systemd/blob/1925f829ab17cee7d65cc8c350d8281f8f41588e/src/oom/oomd-manager.c#L375
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