On Wed 20-03-13 11:03:17, Glauber Costa wrote: > On 03/19/2013 04:55 PM, Michal Hocko wrote: > > On Tue 19-03-13 13:46:50, Michal Hocko wrote: > >> On Tue 05-03-13 17:10:55, Glauber Costa wrote: > >>> For the root memcg, there is no need to rely on the res_counters if hierarchy > >>> is enabled The sum of all mem cgroups plus the tasks in root itself, is > >>> necessarily the amount of memory used for the whole system. Since those figures > >>> are already kept somewhere anyway, we can just return them here, without too > >>> much hassle. > >>> > >>> Limit and soft limit can't be set for the root cgroup, so they are left at > >>> RESOURCE_MAX. Failcnt is left at 0, because its actual meaning is how many > >>> times we failed allocations due to the limit being hit. We will fail > >>> allocations in the root cgroup, but the limit will never the reason. > >> > >> I do not like this very much to be honest. It just adds more hackery... > >> Why cannot we simply not account if nr_cgroups == 1 and move relevant > >> global counters to the root at the moment when a first group is > >> created? > > > > OK, it seems that the very next patch does what I was looking for. So > > why all the churn in this patch? > > Why do you want to make root even more special? > > Because I am operating under the assumption that we want to handle that > transparently and keep things working. If you tell me: "Hey, reading > memory.usage_in_bytes from root should return 0!", then I can get rid of > that. If you simply switch to accounting for root then you do not have to care about this, don't you? > The fact that I keep bypassing when hierarchy is present, it is > more of a reuse of the infrastructure since it's there anyway. > > Also, I would like the root memcg to be usable, albeit cheap, for > projects like memory pressure notifications. root memcg without any childre, right? -- 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>