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 CA5C6155326; Tue, 11 Jun 2024 22:30:05 +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=1718145006; cv=none; b=i/1oLirAjIIDwwzuKGaYl28776CFJsUgFdgnBYg+mfKA8G5CrGNnxfztsKsfCpejZrcLcGZxGR/tzo+Ha6hRH5Z6mwEV3Ehmd+XSDDzoQ5vVITyv0SPv/NCTocX0NPX9K7oGgDuyAc9YtrlDtsUOczMtb5DMO2wjI35j4aGcUlY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718145006; c=relaxed/simple; bh=9RXJ8a97DEsdxRhMEVTCKuqQFatSuESJfhweaOU60zc=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=Ho2Opl+aYs2Jbspd817dxS1t0Pfrqo4PfDaWEvlyu74oD4bfqIDuBUYz79N4zQs+ODG5tBy6dowfzQaQGYqVuYUkuvKgkIxoiLpRQ6hFOKGMZWmKH9YOtMeb598+2VMAUy2b+yRJANTkrhcZa+B/P62aUh4qjGpWJQ9aZMKAAfY= 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=rrBTIbJm; 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="rrBTIbJm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3051BC2BD10; Tue, 11 Jun 2024 22:30:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1718145005; bh=9RXJ8a97DEsdxRhMEVTCKuqQFatSuESJfhweaOU60zc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=rrBTIbJmVn6LABt41IeGe1RUdI5zTMXwNH0wPzMLe00Vo2dyQqKEqw6EnLSZoc+SE jI83hMTGeEmb6WxoVZjEkauQDro0orlF4+kVPLZow+ZEnGZXX2SZ7V8Ca2DjnyeL6+ 1fN/gsFFBSVJ+UnjfEWAtL0rtL70BnrFKvLLvdfs= Date: Tue, 11 Jun 2024 15:30:03 -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, David Rientjes Subject: Re: [PATCH v13] mm: report per-page metadata information Message-Id: <20240611153003.9f1b701e0ed28b129325128a@linux-foundation.org> In-Reply-To: <20240605222751.1406125-1-souravpanda@google.com> References: <20240605222751.1406125-1-souravpanda@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-fsdevel@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 Wed, 5 Jun 2024 22:27:51 +0000 Sourav Panda wrote: > Today, we do not have any observability of per-page metadata > and how much it takes away from the machine capacity. Thus, > we want to describe the amount of memory that is going towards > per-page metadata, which can vary depending on build > configuration, machine architecture, and system use. > > This patch adds 2 fields to /proc/vmstat that can used as shown > below: > > Accounting per-page metadata allocated by boot-allocator: > /proc/vmstat:nr_memmap_boot * PAGE_SIZE > > Accounting per-page metadata allocated by buddy-allocator: > /proc/vmstat:nr_memmap * PAGE_SIZE > > Accounting total Perpage metadata allocated on the machine: > (/proc/vmstat:nr_memmap_boot + > /proc/vmstat:nr_memmap) * PAGE_SIZE Under what circumstances do these change? Only hotplug? It's nasty, but would it be sufficient to simply emit these numbers into dmesg when they change?