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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id g13-20020a7bc4cd000000b003fc02e8ea68sm4810805wmk.13.2023.09.14.06.00.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Sep 2023 06:00:20 -0700 (PDT) Message-ID: <5d6a780e-2945-2b24-bca6-3e38565fe157@redhat.com> Date: Thu, 14 Sep 2023 15:00:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v1 1/1] mm: report per-page metadata information Content-Language: en-US To: Sourav Panda , corbet@lwn.net, gregkh@linuxfoundation.org, rafael@kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, rppt@kernel.org, rdunlap@infradead.org, chenlinxuan@uniontech.com, yang.yang29@zte.com.cn, tomas.mudrunka@gmail.com, bhelgaas@google.com, ivan@cloudflare.com, pasha.tatashin@soleen.com, yosryahmed@google.com, hannes@cmpxchg.org, shakeelb@google.com, kirill.shutemov@linux.intel.com, wangkefeng.wang@huawei.com, adobriyan@gmail.com, vbabka@suse.cz, Liam.Howlett@Oracle.com, surenb@google.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org References: <20230913173000.4016218-1-souravpanda@google.com> <20230913173000.4016218-2-souravpanda@google.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230913173000.4016218-2-souravpanda@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13.09.23 19:30, Sourav Panda wrote: > Adds a new per-node PageMetadata field to > /sys/devices/system/node/nodeN/meminfo > and a global PageMetadata field to /proc/meminfo. This information can > be used by users to see how much memory is being used by per-page > metadata, which can vary depending on build configuration, machine > architecture, and system use. > > Per-page metadata is the amount of memory that Linux needs in order to > manage memory at the page granularity. The majority of such memory is > used by "struct page" and "page_ext" data structures. It's probably worth mentioning, that in contrast to most other "memory consumption" statistics, this metadata might not be included "MemTotal"; when the memmap is allocated using the memblock allocator, it's not included, when it's dynamically allocated using the buddy (e.g., memory hotplug), it's included. -- Cheers, David / dhildenb