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AJvYcCXXX854t4yPwANDy1swVD8i1tu/eOUSbzJllNyW5UCi5a+14ZCjmVmvnzMFnOR+4oqmQT+u7jVRWA==@kvack.org X-Gm-Message-State: AOJu0YxDAeJ+2j5raaRMuUcAfCCSumngIi++cAehoBAp/btcrhpD/EDa 19y6m1JXMDJ4MSbdlncuKZ8Uz7qLhJPQJXq/oiEiwaXog3f/mmp226FhRMQOLhM= X-Google-Smtp-Source: AGHT+IG0/Yi9jDXoMe4SbQutAeX4TmKNmVpk+ce0gjUbWlJ8vwuEqUnLIYyO1WfPbeVRkHQmWS0XzQ== X-Received: by 2002:a05:6214:54c4:b0:6d3:5265:608c with SMTP id 6a1803df08f44-6d39e1077e3mr287671706d6.3.1731561990274; Wed, 13 Nov 2024 21:26:30 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:da5e:d3ff:fee7:26e7]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d3ee773212sm1858856d6.2.2024.11.13.21.26.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Nov 2024 21:26:29 -0800 (PST) Date: Thu, 14 Nov 2024 00:26:24 -0500 From: Johannes Weiner To: David Rientjes Cc: Joshua Hahn , akpm@linux-foundation.org, nphamcs@gmail.com, shakeel.butt@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, chris@chrisdown.name, tj@kernel.org, lizefan.x@bytedance.com, mkoutny@suse.com, corbet@lwn.net, lnyng@meta.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v4 1/1] memcg/hugetlb: Add hugeTLB counters to memcg Message-ID: <20241114052624.GD1564047@cmpxchg.org> References: <20241101204402.1885383-1-joshua.hahnjy@gmail.com> <72688d81-24db-70ba-e260-bd5c74066d27@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A5F9A40326 X-Stat-Signature: p6pojpmwgwparx6eiacqcsu1x4583jso X-Rspam-User: X-HE-Tag: 1731561957-876571 X-HE-Meta: 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 JLOtvdB0 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 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 Wed, Nov 13, 2024 at 02:42:29PM -0800, David Rientjes wrote: > On Mon, 11 Nov 2024, David Rientjes wrote: > > > > The reason that I opted not to include a breakdown of each hugetlb > > > size in memory.stat is only because I wanted to keep the addition that > > > this patch makes as minimal as possible, while still addressing > > > the goal of bridging the gap between memory.stat and memory.current. > > > Users who are curious about this breakdown can see how much memory > > > is used by each hugetlb size by enabling the hugetlb controller as well. > > > > > > > While the patch may be minimal, this is solidifying a kernel API that > > users will start to count on. Users who may be interested in their > > hugetlb usage may not have control over the configuration of their kernel? > > > > Does it make sense to provide a breakdown in memory.stat so that users can > > differentiate between mapping one 1GB hugetlb page and 512 2MB hugetlb > > pages, which are different global resources? > > > > > It's true that this is the case as well for total hugeltb usage, but > > > I felt that not including hugetlb memory usage in memory.stat when it > > > is accounted by memory.current would cause confusion for the users > > > not being able to see that memory.current = sum of memory.stat. On the > > > other hand, seeing the breakdown of how much each hugetlb size felt more > > > like an optimization, and not a solution that bridges a confusion. > > > > > > > If broken down into hugetlb_2048kB and hugetlb_1048576kB on x86, for > > example, users could still do sum of memory.stat, no?> > > > > Friendly ping on this, would there be any objections to splitting the > memory.stat metrics out to be per hugepage size? I don't think it has to be either/or. We can add the total here, and a per-size breakdown in a separate patch (with its own changelog)? That said, a per-size breakdown might make more sense in the hugetlb cgroup controller. You're mentioning separate global resources, which suggests this is about more explicitly controlled hugetlb use. >From a memcg POV, all hugetlb is the same. It's just (non-swappable) memory consumed by the cgroup.