On Mon, Aug 14, 2017 at 03:52:26PM -0700, David Rientjes wrote: > On Mon, 14 Aug 2017, Roman Gushchin wrote: > > > diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt > > index dec5afdaa36d..22108f31e09d 100644 > > --- a/Documentation/cgroup-v2.txt > > +++ b/Documentation/cgroup-v2.txt > > @@ -48,6 +48,7 @@ v1 is available under Documentation/cgroup-v1/. > > 5-2-1. Memory Interface Files > > 5-2-2. Usage Guidelines > > 5-2-3. Memory Ownership > > + 5-2-4. Cgroup-aware OOM Killer > > Random curiousness, why cgroup-aware oom killer and not memcg-aware oom > killer? I don't think we use the term "memcg" somewhere in v2 docs. Do you think that "Memory cgroup-aware OOM killer" is better? > > > 5-3. IO > > 5-3-1. IO Interface Files > > 5-3-2. Writeback > > @@ -1002,6 +1003,37 @@ PAGE_SIZE multiple when read back. > > high limit is used and monitored properly, this limit's > > utility is limited to providing the final safety net. > > > > + memory.oom_kill_all_tasks > > + > > + A read-write single value file which exits on non-root > > s/exits/exists/ Fixed. Thanks! > > > + cgroups. The default is "0". > > + > > + Defines whether the OOM killer should treat the cgroup > > + as a single entity during the victim selection. > > Isn't this true independent of the memory.oom_kill_all_tasks setting? > The cgroup aware oom killer will consider memcg's as logical units when > deciding what to kill with or without memory.oom_kill_all_tasks, right? > > I think you cover this fact in the cgroup aware oom killer section below > so this might result in confusion if described alongside a setting of > memory.oom_kill_all_tasks. > > > + > > + If set, OOM killer will kill all belonging tasks in > > + corresponding cgroup is selected as an OOM victim. > > Maybe > > "If set, the OOM killer will kill all threads attached to the memcg if > selected as an OOM victim." > > is better? Fixed to the following (to conform with core v2 concepts): If set, OOM killer will kill all processes attached to the cgroup if selected as an OOM victim. > > > + > > + Be default, OOM killer respect /proc/pid/oom_score_adj value > > + -1000, and will never kill the task, unless oom_kill_all_tasks > > + is set. > > + > > + memory.oom_priority > > + > > + A read-write single value file which exits on non-root > > s/exits/exists/ Fixed. > > > + cgroups. The default is "0". > > + > > + An integer number within the [-10000, 10000] range, > > + which defines the order in which the OOM killer selects victim > > + memory cgroups. > > + > > + OOM killer prefers memory cgroups with larger priority if they > > + are populated with elegible tasks. > > s/elegible/eligible/ Fixed. > > > + > > + The oom_priority value is compared within sibling cgroups. > > + > > + The root cgroup has the oom_priority 0, which cannot be changed. > > + > > memory.events > > A read-only flat-keyed file which exists on non-root cgroups. > > The following entries are defined. Unless specified > > @@ -1206,6 +1238,36 @@ POSIX_FADV_DONTNEED to relinquish the ownership of memory areas > > belonging to the affected files to ensure correct memory ownership. > > > > > > +Cgroup-aware OOM Killer > > +~~~~~~~~~~~~~~~~~~~~~~~ > > + > > +Cgroup v2 memory controller implements a cgroup-aware OOM killer. > > +It means that it treats memory cgroups as first class OOM entities. > > + > > +Under OOM conditions the memory controller tries to make the best > > +choise of a victim, hierarchically looking for the largest memory > > +consumer. By default, it will look for the biggest task in the > > +biggest leaf cgroup. > > + > > +Be default, all cgroups have oom_priority 0, and OOM killer will > > +chose the largest cgroup recursively on each level. For non-root > > +cgroups it's possible to change the oom_priority, and it will cause > > +the OOM killer to look athe the priority value first, and compare > > +sizes only of cgroups with equal priority. > > Maybe some description of "largest" would be helpful here? I think you > could briefly describe what is accounted for in the decisionmaking. I'm afraid that it's too implementation-defined to be described. Do you have an idea, how to describe it without going too much into details? > s/athe/at the/ Fixed. > > Reading through this, it makes me wonder if doing s/cgroup/memcg/ over > most of it would be better. I don't think memcg is a good user term, but I agree, that it's necessary to highlight the fact that a user should enable memory controller to get this functionality. Added a corresponding note. Thanks! Roman -- 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
