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b=2d6FvCDmUDzCnQWUs6H1g2ELt5Bif7X71Z0u7gzOPi0w7QcSwE+An+R17OMSTIPx9 iCrN2n/gl/q8nd4aqoJcuV+U1EQOnvyWcioTDrjzxiER2uJb1RnEqHkyaLundadVRQ uoD5sWxCE/LS3LSNv7W7xNDhZ+rS13k/+syZCdXE= Date: Tue, 19 Mar 2024 14:33:20 -0700 From: Andrew Morton To: Sourav Panda Cc: corbet@lwn.net, gregkh@linuxfoundation.org, rafael@kernel.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, weixugc@google.com Subject: Re: [PATCH v9 1/1] mm: report per-page metadata information Message-Id: <20240319143320.d1b1ef7f6fa77b748579ba59@linux-foundation.org> In-Reply-To: <20240220214558.3377482-2-souravpanda@google.com> References: <20240220214558.3377482-1-souravpanda@google.com> <20240220214558.3377482-2-souravpanda@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: BBEAB1A0008 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: i36qkez8wmw11dhj91yasgbkt7doyx8a X-HE-Tag: 1710884003-233718 X-HE-Meta: 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 kOkjlumX vFhWekBwfWxe5jl5rE19IxPLeuN7IHrLQGLmFt27rk8F8NI56ZRDhf5hqFuNSfrICwUAlWmfSWUNmzQfS6C/D+7YDNuDYHSLSLo9MjztDwYLXs9ra9vWTcA85OyVIEJPsMHc8zbKrWuHZmcLXcF9gceLIsx+UvasGNthundP6+HVsPt48oPh6t7RCC+L4ifwOEfBEiC/UQ6vr6Ho9NJcF1vEKMenRShss+Y1Xf3dIw6wQzbLJfYL6Zn6GBC9wlg5zmLcS3LBNF/9KOtXFHHEpWbZYKOQryPjm6Gn4KrK85BlOnvL3x+5T1aTW3MaCLXZvtYhGPuLGlYmc+mc= 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, 20 Feb 2024 13:45:58 -0800 Sourav Panda wrote: > Adds two new per-node fields, namely nr_memmap and nr_memmap_boot, > to /sys/devices/system/node/nodeN/vmstat and a global Memmap 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. I yield to no man in my admiration of changelogging but boy, that's a lot of changelogging. Would it be possible to consolidate the [0/N] coverletter and the [1/N] changelog into a single thing please? > Documentation/filesystems/proc.rst | 3 +++ > fs/proc/meminfo.c | 4 ++++ > include/linux/mmzone.h | 4 ++++ > include/linux/vmstat.h | 4 ++++ > mm/hugetlb_vmemmap.c | 17 ++++++++++++---- > mm/mm_init.c | 3 +++ > mm/page_alloc.c | 1 + > mm/page_ext.c | 32 +++++++++++++++++++++--------- > mm/sparse-vmemmap.c | 8 ++++++++ > mm/sparse.c | 7 ++++++- > mm/vmstat.c | 26 +++++++++++++++++++++++- > 11 files changed, 94 insertions(+), 15 deletions(-) And yet we offer the users basically no documentation. The new sysfs file should be documented under Documentation/ABI somewhere and perhaps we could prepare some more expansive user-facing documentation elsewhere? I'd like to hear others' views on the overall usefulness/utility of this change, please?