Re: [PATCH] mm: memcg: export workingset refault stats for cgroup v1

[Shakeel Butt]

On Tue, Aug 16, 2022 at 11:58 AM Yang Shi <shy828301@xxxxxxxxx> wrote:
>
> Workingset refault stats are important and usefule metrics to measure
> how well reclaimer and swapping work and how healthy the services are,
> but they are just available for cgroup v2.  There are still plenty users
> with cgroup v1, export the stats for cgroup v1.
>
> Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
> ---
> I do understand the development of cgroup v1 is actually stalled and
> the community is reluctant to accept new features for v1.  However
> the workingset refault stats are really quite useful and exporting
> two new stats, which have been supported by v2, seems ok IMHO.  So
> hopefully this patch could be considered.  Thanks.
>

Is just workingset refault good enough for your use-case? What about
the other workingset stats? I don't have a strong opinion against
adding these to v1 and I think these specific stats should be fine.
(There is subtlety in exposing objcg based stats (i.e. reparenting) in
v1 due to non-hierarchical stats in v1. I remember Yosry and Muchun
were looking into that.)