On Fri, May 19, 2017 at 3:30 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > On Thu 18-05-17 17:28:04, Roman Gushchin wrote: >> Traditionally, the OOM killer is operating on a process level. >> Under oom conditions, it finds a process with the highest oom score >> and kills it. >> >> This behavior doesn't suit well the system with many running >> containers. There are two main issues: >> >> 1) There is no fairness between containers. A small container with >> a few large processes will be chosen over a large one with huge >> number of small processes. >> >> 2) Containers often do not expect that some random process inside >> will be killed. So, in general, a much safer behavior is >> to kill the whole cgroup. Traditionally, this was implemented >> in userspace, but doing it in the kernel has some advantages, >> especially in a case of a system-wide OOM. >> >> To address these issues, cgroup-aware OOM killer is introduced. >> Under OOM conditions, it looks for a memcg with highest oom score, >> and kills all processes inside. >> >> Memcg oom score is calculated as a size of active and inactive >> anon LRU lists, unevictable LRU list and swap size. >> >> For a cgroup-wide OOM, only cgroups belonging to the subtree of >> the OOMing cgroup are considered. > > While this might make sense for some workloads/setups it is not a > generally acceptable policy IMHO. We have discussed that different OOM > policies might be interesting few years back at LSFMM but there was no > real consensus on how to do that. One possibility was to allow bpf like > mechanisms. Could you explore that path? I agree, I think it needs more thought. I wonder if the real issue is something else. For example 1. Did we overcommit a particular container too much? 2. Do we need something like https://lwn.net/Articles/604212/ to solve the problem? 3. We have oom notifiers now, could those be used (assuming you are interested in non memcg related OOM's affecting a container 4. How do we determine limits for these containers? From a fariness perspective Just trying to understand what leads to the issues you are seeing Balbir -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
