On Tue 12-09-17 21:01:15, Roman Gushchin wrote: > On Mon, Sep 11, 2017 at 01:48:39PM -0700, David Rientjes wrote: > > On Mon, 11 Sep 2017, Roman Gushchin wrote: > > > > > Add a "groupoom" cgroup v2 mount option to enable the cgroup-aware > > > OOM killer. If not set, the OOM selection is performed in > > > a "traditional" per-process way. > > > > > > The behavior can be changed dynamically by remounting the cgroupfs. > > > > I can't imagine that Tejun would be happy with a new mount option, > > especially when it's not required. > > > > OOM behavior does not need to be defined at mount time and for the entire > > hierarchy. It's possible to very easily implement a tunable as part of > > mem cgroup that is propagated to descendants and controls the oom scoring > > behavior for that hierarchy. It does not need to be system wide and > > affect scoring of all processes based on which mem cgroup they are > > attached to at any given time. > > No, I don't think that mixing per-cgroup and per-process OOM selection > algorithms is a good idea. > > So, there are 3 reasonable options: > 1) boot option > 2) sysctl > 3) cgroup mount option > > I believe, 3) is better, because it allows changing the behavior dynamically, > and explicitly depends on v2 (what sysctl lacks). I see your argument here. I would just be worried that we end up really needing more oom strategies in future and those wouldn't fit into memcg mount option scope. So 1/2 sounds more exensible to me long term. Boot time would be easier because we do not have to bother dynamic selection in that case. > So, the only question is should it be opt-in or opt-out option. > Personally, I would prefer opt-out, but Michal has a very strong opinion here. Yes I still strongly believe this has to be opt-in. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
