From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EAD61EB23; Wed, 7 Feb 2024 23:05:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707347105; cv=none; b=PlFhpsvnCw8RNRUCSdDMFQaEhEvAuIb4Auqb7fEdghCBCaxYhaP1dP3l48kxO673OzfOrpj7DZ5Da1DBaKu3OQpPclPnzPjOoem9pSXTjn6PrTMQ1IF/ybvtNvkGKusWlLf5rHlsHZBb/50/DE3RtG7asJNb3uQLQKUnwXFkxAw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707347105; c=relaxed/simple; bh=4BjASI5o6tvggVKonNgqERKXvBBiAS/dqPsYkoe6JOY=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=idtqsOQhGPk3AlvLljIAwP3NUWG4j1qBkX57nkK9deljv65n+hOqLAK/BgRgjC7PTkFYCr8+hvmieNzmw5LwJBSoxXY09+hHQJz61YLxhRS7ZZmXDvVyIUhhcT+AFn2Sj9hYr6amfV1bwQGbLpFvMTjD+BRMZALZOnlPQWvtciY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=jFhQWVq8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="jFhQWVq8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE3BAC433C7; Wed, 7 Feb 2024 23:05:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1707347104; bh=4BjASI5o6tvggVKonNgqERKXvBBiAS/dqPsYkoe6JOY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=jFhQWVq8EzKzmIwAYefphQlZM82G1QoacYIaQqrzJjEkJ8smUiTB7x2X8H4PF4CqV EmIcBSo6fVVTyMyoVWUnCWptsPR7si2Eeuy1YL8glOP/ec7ZgX/g/pU07BZBDxrgjZ rH1GtqasLYCAeJmiNFD5lKiAMfTUF5t9LFSj8bvs= Date: Wed, 7 Feb 2024 15:05:03 -0800 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 v7 0/1] mm: report per-page metadata information Message-Id: <20240207150503.ca18b372f899091af5e6c40b@linux-foundation.org> In-Reply-To: <20240129224204.1812062-1-souravpanda@google.com> References: <20240129224204.1812062-1-souravpanda@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 29 Jan 2024 14:42:03 -0800 Sourav Panda wrote: > This patch adds two new per-node fields, namely nr_page_metadata and > nr_page_metadata_boot to /sys/devices/system/node/nodeN/vmstat 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. I'm not seeing why this is very useful. OK, you look at it and it tells you a number, but what action can a user take based upon that number? Please tell us more about the value of this, the use cases, what prompted you to expend effort on this.