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[109.81.81.105]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a9b1e75ff3bsm576041266b.1.2024.10.30.08.04.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Oct 2024 08:04:55 -0700 (PDT) Date: Wed, 30 Oct 2024 16:04:54 +0100 From: Michal Hocko To: Chris Down Cc: gutierrez.asier@huawei-partners.com, akpm@linux-foundation.org, david@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, hannes@cmpxchg.org, hocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stepanov.anatoly@huawei.com, alexander.kozhevnikov@huawei-partners.com, guohanjun@huawei.com, weiyongjun1@huawei.com, wangkefeng.wang@huawei.com, judy.chenhui@huawei.com, yusongping@huawei.com, artem.kuzin@huawei.com, kang.sun@huawei.com Subject: Re: [RFC PATCH 0/3] Cgroup-based THP control Message-ID: References: <20241030083311.965933-1-gutierrez.asier@huawei-partners.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed 30-10-24 14:45:24, Chris Down wrote: > gutierrez.asier@huawei-partners.com writes: > > New memcg files are exposed: memory.thp_enabled and memory.thp_defrag, which > > have completely the same format as global THP enabled/defrag. > > cgroup controls exist because there are things we want to do for an entire > class of processes (group OOM, resource control, etc). Enabling or disabling > some specific setting is generally not one of them, hence why we got rid of > things like per-cgroup vm.swappiness. We know that these controls do not > compose well and have caused a lot of pain in the past. So my immediate > reaction is a nack on the general concept, unless there's some absolutely > compelling case here. > > I talked a little at Kernel Recipes last year about moving away from sysctl > and other global interfaces and making things more granular. Don't get me > wrong, I think that is a good thing (although, of course, a very large > undertaking) -- but it is a mistake to overload the amount of controls we > expose as part of the cgroup interface. Completely agreed! -- Michal Hocko SUSE Labs