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Date: Thu, 5 Feb 2015 17:25:22 -0500
From: Tejun Heo <tj@kernel.org>
To: Greg Thelen <gthelen@google.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
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        Li Zefan <lizefan@huawei.com>, Hugh Dickins <hughd@google.com>
Subject: Re: [RFC] Making memcg track ownership per address_space or anon_vma
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Hey,

On Thu, Feb 05, 2015 at 02:05:19PM -0800, Greg Thelen wrote:
> >  	A
> >  	+-B    (usage=2M lim=3M min=2M hosted_usage=2M)
> >  	  +-C  (usage=0  lim=2M min=1M shared_usage=2M)
> >  	  +-D  (usage=0  lim=2M min=1M shared_usage=2M)
> >  	  \-E  (usage=0  lim=2M min=0)
...
> Maybe, but I want to understand more about how pressure works in the
> child.  As C (or D) allocates non shared memory does it perform reclaim
> to ensure that its (C.usage + C.shared_usage < C.lim).  Given C's

Yes.

> shared_usage is linked into B.LRU it wouldn't be naturally reclaimable
> by C.  Are you thinking that charge failures on cgroups with non zero
> shared_usage would, as needed, induce reclaim of parent's hosted_usage?

Hmmm.... I'm not really sure but why not?  If we properly account for
the low protection when pushing inodes to the parent, I don't think
it'd break anything.  IOW, allow the amount beyond the sum of low
limits to be reclaimed when one of the sharers is under pressure.

Thanks.

-- 
tejun