On Tue, Jan 30, 2018 at 01:08:52PM +0100, Michal Hocko wrote: > 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. Acked-by: Roman Gushchin <guro@xxxxxx> Thank you! -- 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>
