From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx160.postini.com [74.125.245.160]) by kanga.kvack.org (Postfix) with SMTP id 4C8766B006C for ; Thu, 17 Jan 2013 01:03:40 -0500 (EST) Message-ID: <50F79422.6090405@zytor.com> Date: Wed, 16 Jan 2013 22:03:14 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH v5 0/5] Add movablecore_map boot option References: <1358154925-21537-1-git-send-email-tangchen@cn.fujitsu.com> <50F440F5.3030006@zytor.com> <20130114143456.3962f3bd.akpm@linux-foundation.org> <3908561D78D1C84285E8C5FCA982C28F1C97C2DA@ORSMSX108.amr.corp.intel.com> <20130114144601.1c40dc7e.akpm@linux-foundation.org> <50F647E8.509@jp.fujitsu.com> <20130116132953.6159b673.akpm@linux-foundation.org> <50F72F17.9030805@zytor.com> <50F78750.8070403@jp.fujitsu.com> In-Reply-To: <50F78750.8070403@jp.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: Andrew Morton , "Luck, Tony" , Tang Chen , "jiang.liu@huawei.com" , "wujianguo@huawei.com" , "wency@cn.fujitsu.com" , "laijs@cn.fujitsu.com" , "linfeng@cn.fujitsu.com" , "yinghai@kernel.org" , "rob@landley.net" , "kosaki.motohiro@jp.fujitsu.com" , "minchan.kim@gmail.com" , "mgorman@suse.de" , "rientjes@google.com" , "guz.fnst@cn.fujitsu.com" , "rusty@rustcorp.com.au" , "lliubbo@gmail.com" , "jaegeuk.hanse@gmail.com" , "glommer@parallels.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" On 01/16/2013 09:08 PM, Yasuaki Ishimatsu wrote: > > I thought about the method of specifying the node. But I think > this method is inconvenience. Node number is decided by OS. > So the number is changed easily. > > for example: > > o exmaple 1 > System has 3 nodes: > node0, node1, node2 > > When user remove node1, the system has: > node0, node2 > > But after rebooting the system, the system has: > node0, node1 > > So node2 becomes node1. > > o example 2: > System has 2 nodes: > 0x40000000 - 0x7fffffff : node0 > 0xc0000000 - 0xffffffff : node1 > > When user add a node wchih memory range is [0x80000000 - 0xbfffffff], > system has: > 0x40000000 - 0x7fffffff : node0 > 0xc0000000 - 0xffffffff : node1 > 0x80000000 - 0xbfffffff : node2 > > But after rebooting the system, the system's node may become: > 0x40000000 - 0x7fffffff : node0 > 0x80000000 - 0xbfffffff : node1 > 0xc0000000 - 0xffffffff : node2 > > So node nunber is changed. > > Specifying node number may be easy method than specifying memory > range. But if user uses node number for specifying removable memory, > user always need to care whether node number is changed or not at > every hotplug operation. > Well, there are only two options: 1. The user doesn't care which nodes are movable. In that case, the user may just want to specify a target as a percentage of memory to make movable -- effectively a "slider" on the performance vs. reliability spectrum. The kernel can then assign nodes arbitrarily. 2. If the user *does* care which nodes are movable, then the user needs to be able to specify that *in a way that makes sense to the user*. This may mean involving the DMI information as well as SRAT in order to get "silk screen" type information out. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org