On Thu, Oct 12, 2017 at 02:50:38PM -0700, David Rientjes wrote: > On Wed, 11 Oct 2017, Roman Gushchin wrote: > > Think about it in a different way: we currently compare per-process usage > and userspace has /proc/pid/oom_score_adj to adjust that usage depending > on priorities of that process and still oom kill if there's a memory leak. > Your heuristic compares per-cgroup usage, it's the cgroup-aware oom killer > after all. We don't need a strict memory.oom_priority that outranks all > other sibling cgroups regardless of usage. We need a memory.oom_score_adj > to adjust the per-cgroup usage. The decisionmaking in your earlier > example would be under the control of C/memory.oom_score_adj and > D/memory.oom_score_adj. Problem solved. > > It also solves the problem of userspace being able to influence oom victim > selection so now they can protect important cgroups just like we can > protect important processes today. > > And since this would be hierarchical usage, you can trivially infer root > mem cgroup usage by subtraction of top-level mem cgroup usage. > > This is a powerful solution to the problem and gives userspace the control > they need so that it can work in all usecases, not a subset of usecases. You're right that per-cgroup oom_score_adj may resolve the issue with too strict semantics of oom_priorities. But I believe nobody likes the existing per-process oom_score_adj interface, and there are reasons behind. Especially in case of memcg-OOM, getting the idea how exactly oom_score_adj will work is not trivial. For example, earlier in this thread I've shown an example, when a decision which of two processes should be killed depends on whether it's global or memcg-wide oom, despite both belong to a single cgroup! Of course, it's technically trivial to implement some analog of oom_score_adj for cgroups (and early versions of this patchset did that). But the right question is: is this an interface we want to support for the next many years? I'm not sure. -- 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
