On Thu 09-08-18 13:10:10, David Rientjes wrote: > On Wed, 8 Aug 2018, Michal Hocko wrote: > > > > > > In a cgroup-aware oom killer world, yes, we need the ability to specify > > > > > that the usage of the entire subtree should be compared as a single > > > > > entity with other cgroups. That is necessary for user subtrees but may > > > > > not be necessary for top-level cgroups depending on how you structure your > > > > > unified cgroup hierarchy. So it needs to be configurable, as you suggest, > > > > > and you are correct it can be different than oom.group. > > > > > > > > > > That's not the only thing we need though, as I'm sure you were expecting > > > > > me to say :) > > > > > > > > > > We need the ability to preserve existing behavior, i.e. process based and > > > > > not cgroup aware, for subtrees so that our users who have clear > > > > > expectations and tune their oom_score_adj accordingly based on how the oom > > > > > killer has always chosen processes for oom kill do not suddenly regress. > > > > > > > > Isn't the combination of oom.group=0 and oom.evaluate_together=1 describing > > > > this case? This basically means that if memcg is selected as target, > > > > the process inside will be selected using traditional per-process approach. > > > > > > > > > > No, that would overload the policy and mechanism. We want the ability to > > > consider user-controlled subtrees as a single entity for comparison with > > > other user subtrees to select which subtree to target. This does not > > > imply that users want their entire subtree oom killed. > > > > Yeah, that's why oom.group == 0, no? > > > > Anyway, can we separate this discussion from the current series please? > > We are getting more and more tangent. > > > > Or do you still see the current state to be not mergeable? > > I've said three times in this series that I am fine with it. OK, that wasn't really clear to me because I haven't see any explicit ack from you (well except for the trivial helper patch). So I was not sure. > Roman and I > are discussing the API for making forward progress with the cgroup aware > oom killer itself. When he responds, he can change the subject line if > that would be helpful to you. I do not insist of course but it would be easier to follow if that discussion was separate. -- Michal Hocko SUSE Labs
