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From: Pasha Tatashin <pasha.tatashin@soleen.com>
Date: Wed, 13 Mar 2024 18:37:55 -0400
Message-ID: <CA+CK2bAqdFL-kGmTR8msdy_FSr4Zt7+riJgjdTxX+FN+-M0pLA@mail.gmail.com>
Subject: Re: [PATCH v9 1/1] mm: report per-page metadata information
To: Wei Xu <weixugc@google.com>
Cc: Sourav Panda <souravpanda@google.com>, corbet@lwn.net, gregkh@linuxfoundation.org, 
	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, 
	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
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On Mon, Feb 26, 2024 at 1:12=E2=80=AFPM Wei Xu <weixugc@google.com> wrote:
>
> On Tue, Feb 20, 2024 at 1:46=E2=80=AFPM Sourav Panda <souravpanda@google.=
com> 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.
>
> /proc/vmstat also has the system-wide nr_memmap and nr_memmap_boot.
> Given that nr_memmap in /proc/vmstat provides the same info (in
> different units) as Memmap in /proc/meminfo, it would be better to
> remove Memmap from /proc/meminfo to avoid duplication and confusion.

There are many items both in meminfo and in vmstat. Given that
/proc/meminfo covers all kmem memory, it is beneficial to keep the
kmem part of memmap in meminfo as another classification item.

Pasha