Messages in this thread | | | Date | Sat, 4 Dec 2021 09:36:46 +0000 | From | Chris Down <> | Subject | Re: [PATCH] mm: add group_oom_kill memory event |
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Dan Schatzberg writes: >Our container agent wants to know when a container exits if it was OOM >killed or not to report to the user. We use memory.oom.group = 1 to >ensure that OOM kills within the container's cgroup kill >everything. Existing memory.events are insufficient for knowing if >this triggered: > >1) Our current approach reads memory.events oom_kill and reports the >container was killed if the value is non-zero. This is erroneous in >some cases where containers create their children cgroups with >memory.oom.group=1 as such OOM kills will get counted against the >container cgroup's oom_kill counter despite not actually OOM killing >the entire container. > >2) Reading memory.events.local will fail to identify OOM kills in leaf >cgroups (that don't set memory.oom.group) within the container cgroup. > >This patch adds a new oom_group_kill event when memory.oom.group >triggers to allow userspace to cleanly identify when an entire cgroup >is oom killed. > >Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com>
Thanks! Acking with one minor point on the documentation front.
Acked-by: Chris Down <chris@chrisdown.name>
>--- > Documentation/admin-guide/cgroup-v2.rst | 4 ++++ > include/linux/memcontrol.h | 1 + > mm/memcontrol.c | 5 +++++ > mm/oom_kill.c | 1 + > 4 files changed, 11 insertions(+) > >diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst >index 2aeb7ae8b393..eec830ce2068 100644 >--- a/Documentation/admin-guide/cgroup-v2.rst >+++ b/Documentation/admin-guide/cgroup-v2.rst >@@ -1268,6 +1268,10 @@ PAGE_SIZE multiple when read back. > The number of processes belonging to this cgroup > killed by any kind of OOM killer. > >+ oom_group_kill >+ The number of times all tasks in the cgroup were killed >+ due to memory.oom.group.
Maybe pedantic, but this reads as unclear to me whether in cgroup with 3 tasks we get the value "3" or "1" when a group kill occurs.
Maybe rephrase to not make be about tasks and just say "number of times a group OOM occurred"?
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