linux-kernel - Re: [PATCH REBASED] mm, memcg: Make scan aggression always exclude protection

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Message-ID: <20190531062854.GG6896@dhcp22.suse.cz>
Date:   Fri, 31 May 2019 08:28:54 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Chris Down <chris@...isdown.name>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Tejun Heo <tj@...nel.org>, Roman Gushchin <guro@...com>,
        Dennis Zhou <dennis@...nel.org>, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org, linux-mm@...ck.org, kernel-team@...com
Subject: Re: [PATCH REBASED] mm, memcg: Make scan aggression always exclude
 protection

On Thu 30-05-19 13:52:10, Chris Down wrote:
> Michal Hocko writes:
> > On Wed 29-05-19 23:44:53, Chris Down wrote:
> > > Michal Hocko writes:
> > > > Maybe I am missing something so correct me if I am wrong but the new
> > > > calculation actually means that we always allow to scan even min
> > > > protected memcgs right?
> > > 
> > > We check if the memcg is min protected as a precondition for coming into
> > > this function at all, so this generally isn't possible. See the
> > > mem_cgroup_protected MEMCG_PROT_MIN check in shrink_node.
> > 
> > OK, that is the part I was missing, I got confused by checking the min
> > limit as well here. Thanks for the clarification. A comment would be
> > handy or do we really need to consider min at all?
> 
> You mean as part of the reclaim pressure calculation? Yeah, we still need
> it, because we might only set memory.min, but not set memory.low.

But then the memcg will get excluded as well right?
-- 
Michal Hocko
SUSE Labs