Re: [PATCH 0/9 RFC] cgroup: separate rstat trees

["Michal Koutný" <mkoutny@suse.com>]

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Hello JP.

On Mon, Dec 23, 2024 at 05:13:53PM -0800, JP Kobryn <inwardvessel@gmail.com> wrote:
> I've been experimenting with these changes to allow for separate
> updating/flushing of cgroup stats per-subsystem.

Nice.

> I reached a point where this started to feel stable in my local testing, so I
> wanted to share and get feedback on this approach.

The split is not straight-forwardly an improvement -- there's at least
higher memory footprint and flushing efffectiveness depends on how
individual readers are correlated, OTOH writer correlation affects
updaters when extending the update tree. So a workload dependent effect
can go (in my theory) both sides.
There are also in-kernel consumers of stats, namely memory controller
that's been optimized over the years to balance the tradeoff between
precision and latency.

So do you have any measurements (or expectations) that show how readers
or writers are affected?

Thanks,
Michal

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