On Fri, May 17, 2019 at 5:59 PM Roman Gushchin <guro@xxxxxx> wrote: > > On Fri, May 17, 2019 at 05:18:18PM -0700, Shakeel Butt wrote: > > The memory controller in cgroup v2 exposes memory.events file for each > > memcg which shows the number of times events like low, high, max, oom > > and oom_kill have happened for the whole tree rooted at that memcg. > > Users can also poll or register notification to monitor the changes in > > that file. Any event at any level of the tree rooted at memcg will > > notify all the listeners along the path till root_mem_cgroup. There are > > existing users which depend on this behavior. > > > > However there are users which are only interested in the events > > happening at a specific level of the memcg tree and not in the events in > > the underlying tree rooted at that memcg. One such use-case is a > > centralized resource monitor which can dynamically adjust the limits of > > the jobs running on a system. The jobs can create their sub-hierarchy > > for their own sub-tasks. The centralized monitor is only interested in > > the events at the top level memcgs of the jobs as it can then act and > > adjust the limits of the jobs. Using the current memory.events for such > > centralized monitor is very inconvenient. The monitor will keep > > receiving events which it is not interested and to find if the received > > event is interesting, it has to read memory.event files of the next > > level and compare it with the top level one. So, let's introduce > > memory.events.local to the memcg which shows and notify for the events > > at the memcg level. > > > > Now, does memory.stat and memory.pressure need their local versions. > > IMHO no due to the no internal process contraint of the cgroup v2. The > > memory.stat file of the top level memcg of a job shows the stats and > > vmevents of the whole tree. The local stats or vmevents of the top level > > memcg will only change if there is a process running in that memcg but > > v2 does not allow that. Similarly for memory.pressure there will not be > > any process in the internal nodes and thus no chance of local pressure. > > > > Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> > > --- > > Changelog since v1: > > - refactor memory_events_show to share between events and events.local > > Reviewed-by: Roman Gushchin <guro@xxxxxx> > > You also need to add some stuff into cgroup v2 documentation. > Thanks, will update the doc in the next version. Shakeel
