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Date:   Thu, 14 Sep 2023 15:00:18 +0200
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Subject: Re: [PATCH v1 1/1] mm: report per-page metadata information
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To:     Sourav Panda <souravpanda@google.com>, corbet@lwn.net,
        gregkh@linuxfoundation.org, rafael@kernel.org,
        akpm@linux-foundation.org, mike.kravetz@oracle.com,
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        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,
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        linux-mm@kvack.org
References: <20230913173000.4016218-1-souravpanda@google.com>
 <20230913173000.4016218-2-souravpanda@google.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
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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