Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760974AbYC0UzV (ORCPT ); Thu, 27 Mar 2008 16:55:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758386AbYC0UzK (ORCPT ); Thu, 27 Mar 2008 16:55:10 -0400 Received: from gw.goop.org ([64.81.55.164]:45391 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758259AbYC0UzJ (ORCPT ); Thu, 27 Mar 2008 16:55:09 -0400 Message-ID: <47EC099C.9030609@goop.org> Date: Thu, 27 Mar 2008 13:54:52 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: KAMEZAWA Hiroyuki CC: Yasunori Goto , Christoph Lameter , Linux Kernel Mailing List , Anthony Liguori , Chris Wright Subject: Re: Trying to make use of hotplug memory for xen balloon driver References: <47EAD83A.2000000@goop.org> <20080327095059.5d2759a3.kamezawa.hiroyu@jp.fujitsu.com> <47EB3765.8020702@goop.org> <20080327151115.be9f325d.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080327151115.be9f325d.kamezawa.hiroyu@jp.fujitsu.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2555 Lines: 63 KAMEZAWA Hiroyuki wrote: > On Wed, 26 Mar 2008 22:57:57 -0700 > Jeremy Fitzhardinge wrote: > > >> Ah, I see what it is. I wasn't trying to add enough memory. It adds in >> units of SECTION_SIZE_BITS, which is 2^30 on 32-bit PAE. When I >> increase the initial balloon extension to PAGES_PER_SECTION pages, I >> make some more progress: >> >> xen_balloon: Initialising balloon driver. >> trying to reserve 262144 pages (1073741824 bytes) for balloon >> bootmem alloc of 147456 bytes failed! >> Kernel panic - not syncing: Out of memory >> Pid: 1, comm: swapper Not tainted 2.6.25-rc7-x86-latest.git-dirty #361 >> [] panic+0x49/0x102 >> [] __alloc_bootmem+0x24/0x29 >> [] __alloc_bootmem_node+0x2c/0x34 >> [] zone_wait_table_init+0x45/0x95 >> [] init_currently_empty_zone+0x1d/0xaa >> [] __add_pages+0x88/0xdb >> [] arch_add_memory+0x25/0x2b >> [] add_memory_resource+0x2f/0x36 >> [] balloon_init+0x1b8/0x2b9 >> [] kernel_init+0x137/0x292 >> [] ? kernel_init+0x0/0x292 >> [] ? kernel_init+0x0/0x292 >> [] kernel_thread_helper+0x7/0x10 >> ======================= >> >> >> What's the rationale for setting SECTION_SIZE_BITS to 30? Seems like a >> fairly large chunk. >> >> > At first, I believe usual DIMM size is bigger than SECTION_SIZE_BITS. This is > designed for hardware-based hotplug. > > If you want to use memory-hotplug for virtualized enviroment, it's good to make > this to be smaller chunk. Powerpc/IBM lpar uses 16MB chunk. > > It's a trade-off between section mainainance cost v.s. size of plugged memory. > please find the best. Hm, I tried reducing it to 2^28 (=256M), but I get a compilation failure: CC arch/x86/kernel/asm-offsets.s In file included from /home/jeremy/hg/xen/paravirt/linux/include/linux/suspend.h:11, from /home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/asm-offsets_32.c:11, from /home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/asm-offsets.c:2: /home/jeremy/hg/xen/paravirt/linux/include/linux/mm.h:458:2: error: #error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > FLAGS_RESERVED make[3]: *** [arch/x86/kernel/asm-offsets.s] Error 1 2^29 works. J -- 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/