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From: Shakeel Butt To: Roman Gushchin Cc: Johannes Weiner , Michal =?utf-8?Q?Koutn=C3=BD?= , "T.J. Mercier" , Tejun Heo , Michal Hocko , Muchun Song , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [PATCH] memcg: add hierarchical effective limits for v2 Message-ID: References: <20250205222029.2979048-1-shakeel.butt@linux.dev> <5jwdklebrnbym6c7ynd5y53t3wq453lg2iup6rj4yux5i72own@ay52cqthg3hy> <20250210225234.GB2484@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: F1E64140009 X-Stat-Signature: 4gyh9ff1gtzcyxgpscns5tptne658z4z X-Rspam-User: X-HE-Tag: 1739322488-368830 X-HE-Meta: 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 HsyRFHci UO8pfxQpGyw2yQ4X92SEXqVF26v1W2qspMRP+1C7ED4cD7GN8twW58BfjZzYW7g6QQ1xoFIUXyjhX/vvfvHuNk8vuNAZQKub0TRbAdvzihTQkVLN90r6DeM1Ug+7YpBtxu4KSY7MglnYCW8tsDNor9aNVjTwiw1rt1L0iHwxaZrbOxcCkqdMleLnPmg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Feb 11, 2025 at 04:55:33AM +0000, Roman Gushchin wrote: [...] > > Maybe I'm missing something, but somehow it wasn't a problem for many years. > Nothing really changed here. > > So maybe someone can come up with a better explanation of a specific problem > we're trying to solve here? The most simple explanation is visibility. Workloads that used to run solo are being moved to a multi-tenant but non-overcommited environment and they need to know their capacity which they used to get from system metrics. Now they have to get from cgroup limit files but usage of cgroup namespace limits those workloads to extract the needed information.