Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751783Ab3JAGWL (ORCPT ); Tue, 1 Oct 2013 02:22:11 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:29080 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751119Ab3JAGWK (ORCPT ); Tue, 1 Oct 2013 02:22:10 -0400 X-IronPort-AV: E=Sophos;i="4.90,1012,1371052800"; d="scan'208";a="8662579" Message-ID: <524A69DA.9050701@cn.fujitsu.com> Date: Tue, 01 Oct 2013 14:21:14 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Ingo Molnar CC: Zhang Yanfei , Andrew Morton , "H. Peter Anvin" , Tejun Heo , Lai Jiangshan , Wen Congyang , isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, Tang Chen , linux-doc@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux MM , imtangchen@gmail.com Subject: Re: [PATCH -mm] mm, memory-hotpulg: Rename movablenode boot option to movable_node References: <5249B7C6.7010902@gmail.com> <20131001054646.GA17220@gmail.com> In-Reply-To: <20131001054646.GA17220@gmail.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/10/01 14:20:14, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/10/01 14:20:15, Serialize complete at 2013/10/01 14:20:15 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2230 Lines: 50 Hello Ingo, On 10/01/2013 01:46 PM, Ingo Molnar wrote: > > * Zhang Yanfei wrote: > >> @@ -153,11 +153,18 @@ config MOVABLE_NODE >> help >> Allow a node to have only movable memory. Pages used by the kernel, >> such as direct mapping pages cannot be migrated. So the corresponding >> + memory device cannot be hotplugged. This option allows the following >> + two things: >> + - When the system is booting, node full of hotpluggable memory can >> + be arranged to have only movable memory so that the whole node can >> + be hotplugged. (need movable_node boot option specified). > > So this is _exactly_ what I complained about earlier: why is the > movable_node boot option needed to get that extra functionality? It's > clearly not just a drop-in substitute to CONFIG_MOVABLE_NODE but extends > its functionality, right? Generally speaking, CONFIG_MOVABLE_NODE is used to allow a node to have only movable memory. Firstly, we didn't support the functionality to support boot-time configuration. That said, before this patchset, we only support later hot-add node to have only movable memory but any node that is dectected at boot-time cannot. So here is movable_node option, to protect the kernel from using hotpluggable memory at boot-time and if a node is full of hotpluggable memory, this node is arranged to have only movable memory and can be hot-removed after the system is up. > > Boot options are _very_ poor user interface. If you don't want to enable > it by default then turn this sub-functionality into > CONFIG_MOVABLE_NODE_AUTO and keep it default-off - but don't pretend that > this is only about CONFIG_MOVABLE_NODE alone - it isnt: as described above > the 'movable_node' is needed for the full functionality to be available! As explained above, we need the boot option to only disable boot-time memory-hotplug configuration not the whole MOVABLE_NODE functionality. Thanks -- Thanks. Zhang Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/