On Wed, Sep 13, 2017 at 02:29:14PM +0200, Michal Hocko wrote:

On Mon 11-09-17 13:44:39, David Rientjes wrote:

quoted

On Mon, 11 Sep 2017, Roman Gushchin wrote:

quoted

This patchset makes the OOM killer cgroup-aware.

v8:
  - Do not kill tasks with OOM_SCORE_ADJ -1000
  - Make the whole thing opt-in with cgroup mount option control
  - Drop oom_priority for further discussions

Nack, we specifically require oom_priority for this to function correctly, 
otherwise we cannot prefer to kill from low priority leaf memcgs as 
required.

While I understand that your usecase might require priorities I do not
think this part missing is a reason to nack the cgroup based selection
and kill-all parts. This can be done on top. The only important part
right now is the current selection semantic - only leaf memcgs vs. size
of the hierarchy).

I agree.

I strongly believe that comparing only leaf memcgs
is more straightforward and it doesn't lead to unexpected results as
mentioned before (kill a small memcg which is a part of the larger
sub-hierarchy).

One of two main goals of this patchset is to introduce cgroup-level
fairness: bigger cgroups should be affected more than smaller,
despite the size of tasks inside. I believe the same principle
should be used for cgroups.

Also, the opposite will make oom_semantics more weird: it will mean
kill all tasks, but also treat memcg as a leaf cgroup.

I didn't get to read the new version of this series yet and hope to get
to it soon.

Thanks!

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