Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759956Ab0KRQ7R (ORCPT ); Thu, 18 Nov 2010 11:59:17 -0500 Received: from smtp-out.google.com ([216.239.44.51]:46368 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759937Ab0KRQ7Q convert rfc822-to-8bit (ORCPT ); Thu, 18 Nov 2010 11:59:16 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=MALSXPRgNKkU8ZQqVMPQ+lya/CnPnhjSa0/3ZUKjBid/weEDBGpZEscJGZOuOKhDlA 0KkZVtoUCmN9kEqL/g1Q== MIME-Version: 1.0 In-Reply-To: References: <20101117020759.016741414@intel.com> <20101117021000.916235444@intel.com> <1290019807.9173.3789.camel@nimitz> <1290030945.9173.4211.camel@nimitz> Date: Thu, 18 Nov 2010 08:59:11 -0800 Message-ID: Subject: Re: [7/8,v3] NUMA Hotplug Emulator: extend memory probe interface to support NUMA From: Aaron Durbin To: David Rientjes Cc: Dave Hansen , shaohui.zheng@intel.com, Andrew Morton , 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, Haicheng Li , Wu Fengguang , Greg KH Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2108 Lines: 49 On Wed, Nov 17, 2010 at 2:44 PM, David Rientjes wrote: > On Wed, 17 Nov 2010, Dave Hansen wrote: > >> > Then, export the amount of memory that is actually physically present in >> > the e820 but was truncated by mem= >> >> I _think_ that's already effectively done in /sys/firmware/memmap. >> > > Ok. > > It's a little complicated because we don't export each online node's > physical address range so you have to parse the dmesg to find what nodes > were allocated at boot and determine how much physically present memory > you have that's hidden but can be hotplugged using the probe files. > > Adding Aaron Durbin to the cc because he has a patch > that exports the physical address range of each node in their sysfs > directories. Is this something that is needed upstream? I can post it if that is the case. Sorry, I don't have a lot of context w.r.t. this thread. > >> > and allow users to hot-add the memory >> > via the probe interface. ?Add a writeable 'node' file to offlined memory >> > section directories and allow it to be changed prior to online. >> >> That would work, in theory. ?But, in practice, we allocate the mem_map[] >> at probe time. ?So, we've already effectively picked a node at probe. >> That was done because the probe is equivalent to the hardware "add" >> event. ?Once the hardware where in the address space the memory is, it >> always also knows the node. >> >> But, I guess it also wouldn't be horrible if we just hot-removed and >> hot-added an offline section if someone did write to a node file like >> you're suggesting. ?It might actually exercise some interesting code >> paths. >> > > Since the pages are offline you should be able to modify the memmap when > the 'node' file is written and use populate_memnodemap() since that file > is only writeable in an offline state. > -- 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/