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a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697615521; bh=woRiGHLdU4jN8s9X4H6woCtgWH/Emk3o/3wRf0O5stM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wvJymKSbfEo8z0QgshiW8SmB7gEJp1YGkZx8jhEcuTRaIvBKTQHxQKNwgKyUmTugS HuBTL0EbJ2FBW5ZgxZXEUgC21DfKHZi1yuBPeuAjFGUAl2r7ETzrBBOrG2rUeYKHAr WXZjd1aR0FGnVZ6juMQ/GYSRrjvD8vr5EuIb1MWA= Date: Wed, 18 Oct 2023 09:51:58 +0200 From: Greg KH To: Sourav Panda Cc: corbet@lwn.net, rafael@kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, rppt@kernel.org, david@redhat.com, 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, willy@infradead.org Subject: Re: [PATCH v2 1/1] mm: report per-page metadata information Message-ID: <2023101824-ventricle-hacked-6450@gregkh> References: <20231018005548.3505662-1-souravpanda@google.com> <20231018005548.3505662-2-souravpanda@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231018005548.3505662-2-souravpanda@google.com> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 92F0E14002E X-Stat-Signature: kzohntwrn7rt97eog6bj86jr9ap8hx9j X-HE-Tag: 1697615524-742587 X-HE-Meta: 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 vn+asv1/ gJbidhMGV7tbcRLwLxCEb/gVo60DKXMlgizF4Ql6HEizerGTOmRfmntpQDel9y6G5TD00RPlKXTxggdX87axplMs83eWfcnB3GAAvxVLBymJZJdzaSaObhklVZw89ENfhpy6Gs1qO7HBm64swxgWUs5XTGyULXo5ev8Ibcmzw7gYqKns76/xqCXIry5Zmy5FtFeqrI6TrKYjK2yiVX3AAW+umrID0QWIB7ZL4TDAvBW/pjU59NB4t6SiDDuIxc9AjUlSk+mIzn/fqDYaZY4/80kY/Yw3Dz8ml0MHVD2AhIQjIPMJjxYgzg93c1OViU4DXDzki4TRh+sK3YGRnUesF5dE9rtKAaM8rEwRwK3mMlZT3dws= 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: On Tue, Oct 17, 2023 at 05:55:48PM -0700, 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. In contrast to > most other memory consumption statistics, per-page metadata might not > be included in MemTotal. For example, MemTotal does not include memblock > allocations but includes buddy allocations. While on the other hand, > per-page metadata would include both memblock and buddy allocations. > > This memory depends on build configurations, machine architectures, and > the way system is used: > > Build configuration may include extra fields into "struct page", > and enable / disable "page_ext" > Machine architecture defines base page sizes. For example 4K x86, > 8K SPARC, 64K ARM64 (optionally), etc. The per-page metadata > overhead is smaller on machines with larger page sizes. > System use can change per-page overhead by using vmemmap > optimizations with hugetlb pages, and emulated pmem devdax pages. > Also, boot parameters can determine whether page_ext is needed > to be allocated. This memory can be part of MemTotal or be outside > MemTotal depending on whether the memory was hot-plugged, booted with, > or hugetlb memory was returned back to the system. > > Suggested-by: Pasha Tatashin > Signed-off-by: Sourav Panda > Change-Id: I4351791c9f4c1e9759cbd8e646e808565dbb595f checkpatch.pl should have said that "Change-Id:" should be removed, why didn't you run this on your patch before submitting it? thanks, greg k-h