Date: Thu, 21 Sep 2017 01:27:29 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
To: Roman Gushchin <guro@fb.com>
cc: Michal Hocko <mhocko@kernel.org>, linux-mm@kvack.org,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Andrew Morton <akpm@linux-foundation.org>, Tejun Heo <tj@kernel.org>,
        kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [v8 0/4] cgroup-aware OOM killer
In-Reply-To: <20170920222403.GA4729@castle>
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On Wed, 20 Sep 2017, Roman Gushchin wrote:

> > It's actually much more complex because in our environment we'd need an 
> > "activity manager" with CAP_SYS_RESOURCE to control oom priorities of user 
> > subcontainers when today it need only be concerned with top-level memory 
> > cgroups.  Users can create their own hierarchies with their own oom 
> > priorities at will, it doesn't alter the selection heuristic for another 
> > other user running on the same system and gives them full control over the 
> > selection in their own subtree.  We shouldn't need to have a system-wide 
> > daemon with CAP_SYS_RESOURCE be required to manage subcontainers when 
> > nothing else requires it.  I believe it's also much easier to document: 
> > oom_priority is considered for all sibling cgroups at each level of the 
> > hierarchy and the cgroup with the lowest priority value gets iterated.
> 
> I do agree actually. System-wide OOM priorities make no sense.
> 
> Always compare sibling cgroups, either by priority or size, seems to be
> simple, clear and powerful enough for all reasonable use cases. Am I right,
> that it's exactly what you've used internally? This is a perfect confirmation,
> I believe.
> 

We've used it for at least four years, I added my Tested-by to your patch, 
we would convert to your implementation if it is merged upstream, and I 
would enthusiastically support your patch if you would integrate it back 
into your series.