On Thu, Jun 23, 2022 at 9:07 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > On Thu 23-06-22 18:03:31, Vasily Averin wrote: > > Dear Michal, > > do you still have any concerns about this patch set? > > Yes, I do not think we have concluded this to be really necessary. IIRC > Roman would like to see lingering cgroups addressed in not-so-distant > future (http://lkml.kernel.org/r/Ypd2DW7id4M3KJJW@carbon) and we already > have a limit for the number of cgroups in the tree. So why should we > chase after allocations that correspond the cgroups and somehow try to > cap their number via the memory consumption. This looks like something > that will get out of sync eventually and it also doesn't seem like the > best control to me (comparing to an explicit limit to prevent runaways). > -- Let me give a counter argument to that. On a system running multiple workloads, how can the admin come up with a sensible limit for the number of cgroups? There will definitely be jobs that require much more number of sub-cgroups. Asking the admins to dynamically tune another tuneable is just asking for more complications. At the end all the users would just set it to max. I would recommend to see the commit ac7b79fd190b ("inotify, memcg: account inotify instances to kmemcg") where there is already a sysctl (inotify/max_user_instances) to limit the number of instances but there was no sensible way to set that limit on a multi-tenant system.
