Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755854Ab0LBBu5 (ORCPT ); Wed, 1 Dec 2010 20:50:57 -0500 Received: from mga01.intel.com ([192.55.52.88]:41179 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753581Ab0LBBu4 (ORCPT ); Wed, 1 Dec 2010 20:50:56 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.59,285,1288594800"; d="scan'208";a="632230554" Date: Thu, 2 Dec 2010 08:27:16 +0800 From: Shaohui Zheng To: "shaohui.zheng@linux.intel.com" , David Rientjes Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, haicheng.li@linux.intel.com, lethal@linux-sh.org, ak@linux.intel.com, shaohui.zheng@linux.intel.com, dave@linux.vnet.ibm.com, gregkh@suse.de, Haicheng Li Subject: Re: [8/8, v6] NUMA Hotplug Emulator: implement debugfs interface for memory probe Message-ID: <20101202002716.GA13693@shaohui> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1660 Lines: 34 > > I doubt either Greg or Dave suggested adding duplicate interfaces for the > same functionality. > > The difference is that we needed to add the add_node interface in a new > mem_hotplug debugfs directory because it's only useful for debugging > kernel code and, thus, doesn't really have an appropriate place in sysfs. > Nobody is going to use add_node unless they lack hotpluggable memory > sections in their SRAT and want to debug the memory hotplug callers. For > example, I already wrote all of this node hotplug emulation stuff when I > wrote the node hotplug support for SLAB. > > Memory hotplug, however, does serve a non-debugging function and is > appropriate in sysfs since this is how people hotplug memory. It's an ABI > that we can't simply remove without deprecation over a substantial period > of time and in this case it doesn't seem to have a clear advantage. We > need not add special emulation support for something that is already > possible for real systems, so adding a duplicate interface in debugfs is > inappropriate. so we should still keep the sysfs memory/probe interface without any modifications, but for the debugfs mem_hotplug/probe interface, we can add the memory region to a desired node. It is an extention for the sysfs memory/probe interface, it can be used for memory hotplug emulation. Do I understand it correctly? -- Thanks & Regards, Shaohui -- 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/