On Tue 02-10-12 13:15:43, Glauber Costa wrote: > On 10/01/2012 09:00 PM, Michal Hocko wrote: > > On Tue 25-09-12 12:52:50, Glauber Costa wrote: > >> > For the root memcg, there is no need to rely on the res_counters. > > This is true only if there are no children groups but once there is at > > least one we have to move global statistics into root res_counter and > > start using it since then. This is a tricky part because it has to be > > done atomically so that we do not miss anything. > > > Why can't we shortcut it all the time? Because it has its own tasks and we are still not at use_hierarchy := 1 > It makes a lot of sense to use the root cgroup as the sum of everything, > IOW, global counters. Otherwise you are left in a situation where you > had global statistics, and all of a sudden, when a group is created, you > start having just a subset of that, excluding the tasks in root. Yes because if there are no other tasks then, well, global == root. Once you have more groups (with tasks of course) then it depends on our favorite use_hierarchy buddy. > If we can always assume root will have the sum of *all* tasks, including > the ones in root, we should never need to rely on root res_counters. but we are not there yet. -- 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>