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[37.188.133.87]) by smtp.gmail.com with ESMTPSA id b11sm3567835wrx.89.2020.02.13.08.36.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Feb 2020 08:36:38 -0800 (PST) Date: Thu, 13 Feb 2020 17:36:36 +0100 From: Michal Hocko To: Tejun Heo Cc: Johannes Weiner , Andrew Morton , Roman Gushchin , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH v2 3/3] mm: memcontrol: recursive memory.low protection Message-ID: <20200213163636.GH31689@dhcp22.suse.cz> References: <20191219200718.15696-1-hannes@cmpxchg.org> <20191219200718.15696-4-hannes@cmpxchg.org> <20200130170020.GZ24244@dhcp22.suse.cz> <20200203215201.GD6380@cmpxchg.org> <20200211164753.GQ10636@dhcp22.suse.cz> <20200212170826.GC180867@cmpxchg.org> <20200213074049.GA31689@dhcp22.suse.cz> <20200213135348.GF88887@mtj.thefacebook.com> <20200213154731.GE31689@dhcp22.suse.cz> <20200213155249.GI88887@mtj.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200213155249.GI88887@mtj.thefacebook.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 13-02-20 10:52:49, Tejun Heo wrote: > Hello, > > On Thu, Feb 13, 2020 at 04:47:31PM +0100, Michal Hocko wrote: > > Well, I would tend to agree but I can see an existing cgroup hierarchy > > imposed by systemd and that is more about "logical" organization of > > processes based on their purpose than anything resembling resources. > > So what can we do about that to make it all work? > > systemd right now isn't configuring any resource control by default, > so I'm not sure why it is relevant in this discussion. AFAIK systemd already offers knobs to configure resource controls [1]. Besides that we are talking about memcg features which are available only unified hieararchy and that is what systemd is using already. > You gotta > change the layout to configure resource control no matter what and > it's pretty easy to do. systemd folks are planning to integrate higher > level resource control features, so my expectation is that the default > layout is gonna change as it develops. Do you have any pointers to those discussions? I am not really following systemd development. Anyway, I am skeptical that systemd can do anything much more clever than placing cgroups with a resource control under the root cgroup. At least not without some tagging which workloads are somehow related. That being said, I do not really blame systemd here. We are not making their life particularly easy TBH. [1] https://www.freedesktop.org/software/systemd/man/systemd.resource-control.html -- Michal Hocko SUSE Labs