From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by kanga.kvack.org (Postfix) with ESMTP id 642216B6854 for ; Mon, 3 Dec 2018 04:22:27 -0500 (EST) Received: by mail-wm1-f72.google.com with SMTP id t1so2510951wmt.5 for ; Mon, 03 Dec 2018 01:22:27 -0800 (PST) Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr. [192.134.164.83]) by mx.google.com with ESMTPS id w8si10319886wrp.196.2018.12.03.01.22.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Dec 2018 01:22:25 -0800 (PST) Subject: Re: [PATCH 0/9] Allow persistent memory to be used like normal RAM References: <20181022201317.8558C1D8@viggo.jf.intel.com> From: Brice Goglin Message-ID: Date: Mon, 3 Dec 2018 10:22:24 +0100 MIME-Version: 1.0 In-Reply-To: <20181022201317.8558C1D8@viggo.jf.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen , linux-kernel@vger.kernel.org Cc: dan.j.williams@intel.com, dave.jiang@intel.com, zwisler@kernel.org, vishal.l.verma@intel.com, thomas.lendacky@amd.com, akpm@linux-foundation.org, mhocko@suse.com, linux-nvdimm@lists.01.org, linux-mm@kvack.org, ying.huang@intel.com, fengguang.wu@intel.com Le 22/10/2018 à 22:13, Dave Hansen a écrit : > Persistent memory is cool. But, currently, you have to rewrite > your applications to use it. Wouldn't it be cool if you could > just have it show up in your system like normal RAM and get to > it like a slow blob of memory? Well... have I got the patch > series for you! > > This series adds a new "driver" to which pmem devices can be > attached. Once attached, the memory "owned" by the device is > hot-added to the kernel and managed like any other memory. On > systems with an HMAT (a new ACPI table), each socket (roughly) > will have a separate NUMA node for its persistent memory so > this newly-added memory can be selected by its unique NUMA > node. Hello Dave What happens on systems without an HMAT? Does this new memory get merged into existing NUMA nodes? Also, do you plan to have a way for applications to find out which NUMA nodes are "real DRAM" while others are "pmem-backed"? (something like a new attribute in /sys/devices/system/node/nodeX/) Or should we use HMAT performance attributes for this? Brice