From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE. Date: Wed, 14 Aug 2013 14:22:22 -0400 Message-ID: <520BCADE.2040109@gmail.com> References: <1375956979-31877-1-git-send-email-tangchen@cn.fujitsu.com> <20130812145016.GI15892@htj.dyndns.org> <52090225.6070208@gmail.com> <20130812154623.GL15892@htj.dyndns.org> <52090AF6.6020206@gmail.com> <20130812162247.GM15892@htj.dyndns.org> <520914D5.7080501@gmail.com> <52091A10.4030501@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52091A10.4030501@zytor.com> Sender: owner-linux-mm@kvack.org To: "H. Peter Anvin" Cc: Tang Chen , Tejun Heo , Tang Chen , robert.moore@intel.com, lv.zheng@intel.com, rjw@sisk.pl, lenb@kernel.org, tglx@linutronix.de, mingo@elte.hu, akpm@linux-foundation.org, trenn@suse.de, yinghai@kernel.org, jiang.liu@huawei.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, mgorman@suse.de, minchan@kernel.org, mina86@mina86.com, gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, riel@redhat.com, jweiner@redhat.com, prarit@redhat.com, zhangyanfei@cn.fujitsu.com, yanghy@cn.fujitsu.com, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org, kosaki.motohiro@gmail.com List-Id: linux-acpi@vger.kernel.org (8/12/13 1:23 PM), H. Peter Anvin wrote: > On 08/12/2013 10:01 AM, Tang Chen wrote: >>> >>>> I'm just thinking of a more extreme case. For example, if a machine >>>> has only one node hotpluggable, and the kernel resides in that node. >>>> Then the system has no hotpluggable node. >>> >>> Yeah, sure, then there's no way that node can be hotpluggable and the >>> right thing to do is booting up the machine and informing the userland >>> that memory is not hotpluggable. >>> >>>> If we can prevent the kernel from using hotpluggable memory, in such >>>> a machine, users can still do memory hotplug. >>>> >>>> I wanted to do it as generic as possible. But yes, finding out the >>>> nodes the kernel resides in and make it unhotpluggable can work. >>> >>> Short of being able to remap memory under the kernel, I don't think >>> this can be very generic and as a compromise trying to keep as many >>> hotpluggable nodes as possible doesn't sound too bad. >> >> I think making one of the node hotpluggable is better. But OK, it is >> no big deal. There won't be such machine in reality, I think. :) >> > > The user may very well have configured a system with mirrored memory for > the kernel node as that will be non-hotpluggable, but not for the > others. One can wonder how much that actually buys in real life, but > still... Note. Such system is much cheaper than full memory mirroring system. That's one of reason why server vendors are interesting in hot plugging. -- 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