On Tue 30-01-18 11:58:51, Roman Gushchin wrote: > On Tue, Jan 30, 2018 at 09:54:45AM +0100, Michal Hocko wrote: > > On Mon 29-01-18 11:11:39, Tejun Heo wrote: > > Hello, Michal! > > > diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt > > index 2eaed1e2243d..67bdf19f8e5b 100644 > > --- a/Documentation/cgroup-v2.txt > > +++ b/Documentation/cgroup-v2.txt > > @@ -1291,8 +1291,14 @@ This affects both system- and cgroup-wide OOMs. For a cgroup-wide OOM > > the memory controller considers only cgroups belonging to the sub-tree > > of the OOM'ing cgroup. > > > > -The root cgroup is treated as a leaf memory cgroup, so it's compared > > -with other leaf memory cgroups and cgroups with oom_group option set. > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > IMO, this statement is important. Isn't it? > > > +Leaf cgroups are compared based on their cumulative memory usage. The > > +root cgroup is treated as a leaf memory cgroup as well, so it's > > +compared with other leaf memory cgroups. Due to internal implementation > > +restrictions the size of the root cgroup is a cumulative sum of > > +oom_badness of all its tasks (in other words oom_score_adj of each task > > +is obeyed). Relying on oom_score_adj (appart from OOM_SCORE_ADJ_MIN) > > +can lead to overestimating of the root cgroup consumption and it is > > Hm, and underestimating too. Also OOM_SCORE_ADJ_MIN isn't any different > in this case. Say, all tasks except a small one have OOM_SCORE_ADJ set to > -999, this means the root croup has extremely low chances to be elected. > > > +therefore discouraged. This might change in the future, though. > > Other than that looks very good to me. This? diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index 2eaed1e2243d..34ad80ee90f2 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -1291,8 +1291,15 @@ This affects both system- and cgroup-wide OOMs. For a cgroup-wide OOM the memory controller considers only cgroups belonging to the sub-tree of the OOM'ing cgroup. -The root cgroup is treated as a leaf memory cgroup, so it's compared -with other leaf memory cgroups and cgroups with oom_group option set. +Leaf cgroups and cgroups with oom_group option set are compared based +on their cumulative memory usage. The root cgroup is treated as a +leaf memory cgroup as well, so it's compared with other leaf memory +cgroups. Due to internal implementation restrictions the size of +the root cgroup is a cumulative sum of oom_badness of all its tasks +(in other words oom_score_adj of each task is obeyed). Relying on +oom_score_adj (appart from OOM_SCORE_ADJ_MIN) can lead to over or +underestimating of the root cgroup consumption and it is therefore +discouraged. This might change in the future, though. If there are no cgroups with the enabled memory controller, the OOM killer is using the "traditional" process-based approach. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
