On Fri 15-09-17 12:55:55, David Rientjes wrote:

On Fri, 15 Sep 2017, Roman Gushchin wrote:

quoted

quoted

But then you just enforce a structural restriction on your configuration
because
	root
        /  \
       A    D
      /\   
     B  C

is a different thing than
	root
        / | \
       B  C  D

I actually don't have a strong argument against an approach to select
largest leaf or kill-all-set memcg. I think, in practice there will be
no much difference.

The only real concern I have is that then we have to do the same with
oom_priorities (select largest priority tree-wide), and this will limit
an ability to enforce the priority by parent cgroup.

Yes, oom_priority cannot select the largest priority tree-wide for exactly 
that reason.  We need the ability to control from which subtree the kill 
occurs in ancestor cgroups.  If multiple jobs are allocated their own 
cgroups and they can own memory.oom_priority for their own subcontainers, 
this becomes quite powerful so they can define their own oom priorities.   
Otherwise, they can easily override the oom priorities of other cgroups.

Could you be more speicific about your usecase? What would be a
problem If we allow to only increase priority in children (like other
hierarchical controls).

-- 
Michal Hocko
SUSE Labs

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