From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
Subject: Re: memcg: softlimit on internal nodes
Date: Tue, 23 Apr 2013 15:06:27 +0200
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To: Michel Lespinasse <walken-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Balbir Singh <bsingharora-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Ying Han <yinghan-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

On Tue 23-04-13 05:51:36, Michel Lespinasse wrote:
[...]
> The issue I see is that even when people configure soft limits B+C <
> A, your current proposal still doesn't "leave the other alone" as
> Glauber and I think we should.

If B+C < A then B resp. C get reclaimed only if A is over the limit
which means that it couldn't reclaimed enough to get bellow the limit
when we bang on it before B and C. We can update the implementation
later to be more clever in situations like this but this is not that
easy because once we get away from the round robin over the tree then we
might end up having other issues - like unfairness etc... That's why I
wanted to have this as simple as possible.
-- 
Michal Hocko
SUSE Labs