Messages in this thread | | | From | Yang Shi <> | Date | Mon, 1 Mar 2021 09:07:03 -0800 | Subject | Re: [PATCH] doc: memcontrol: add description for oom_kill |
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On Mon, Mar 1, 2021 at 4:15 AM Michal Hocko <mhocko@suse.com> wrote: > > On Fri 26-02-21 08:42:29, Yang Shi wrote: > > On Thu, Feb 25, 2021 at 11:30 PM Michal Hocko <mhocko@suse.com> wrote: > > > > > > On Thu 25-02-21 18:12:54, Yang Shi wrote: > > > > When debugging an oom issue, I found the oom_kill counter of memcg is > > > > confusing. At the first glance without checking document, I thought it > > > > just counts for memcg oom, but it turns out it counts both global and > > > > memcg oom. > > > > > > Yes, this is the case indeed. The point of the counter was to count oom > > > victims from the memcg rather than matching that to the source of the > > > oom. Rememeber that this could have been a memcg oom up in the > > > hierarchy as well. Counting victims on the oom origin could be equally > > > > Yes, it is updated hierarchically on v2, but not on v1. I'm supposed > > this is because v1 may work in non-hierarchcal mode? If this is the > > only reason we may be able to remove this to get aligned with v2 since > > non-hierarchal mode is no longer supported. > > I believe the reson is that v1 can have tasks in the intermediate > (non-leaf) memcgs. So you wouldn't have a way to tell whether the oom > kill has happened in such a memcg or somewhere down the hierarchy.
Aha, I forgot it, that's bad. Although we don't have tasks in intermediate nodes in practice, I do understand it is not forbidden as cgroup v2.
> -- > Michal Hocko > SUSE Labs
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