Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261534AbVBRWVJ (ORCPT ); Fri, 18 Feb 2005 17:21:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261535AbVBRWVJ (ORCPT ); Fri, 18 Feb 2005 17:21:09 -0500 Received: from e34.co.us.ibm.com ([32.97.110.132]:29432 "EHLO e34.co.us.ibm.com") by vger.kernel.org with ESMTP id S261534AbVBRWVB (ORCPT ); Fri, 18 Feb 2005 17:21:01 -0500 Subject: Re: [RFC][PATCH] Memory Hotplug From: Dave Hansen To: Rik van Riel Cc: Linux Kernel Mailing List , lhms , linux-mm , Andy Whitcroft In-Reply-To: References: <1108685033.6482.38.camel@localhost> <1108685111.6482.40.camel@localhost> Content-Type: text/plain Date: Fri, 18 Feb 2005 14:20:46 -0800 Message-Id: <1108765246.6482.135.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1855 Lines: 49 On Fri, 2005-02-18 at 16:52 -0500, Rik van Riel wrote: > On Thu, 17 Feb 2005, Dave Hansen wrote: > > The attached patch is a prototype implementation of memory hot-add. It > > allows you to boot your system, and add memory to it later. Why would > > you want to do this? > > I want it so I can grow Xen guests after they have been booted > up. Being able to hot-add memory is essential for dynamically > resizing the memory of various guest OSes, to readjust them for > the workload. That's the same thing we like about it on ppc64 partitions. > Memory hot-remove isn't really needed with Xen, the balloon > driver takes care of that. You can free up individual pages back to the hypervisor, but you might also want the opportunity to free up some unused mem_map if you shrink the partition by a large amount. > > I can post individual patches if anyone would like to comment on them. > > I'm interested. I want to get this stuff working with Xen ;) You can either pull them from here: http://www.sr71.net/patches/2.6.11/2.6.11-rc3-mhp1/broken-out/ or grab the whole tarball: http://www.sr71.net/patches/2.6.11/2.6.11-rc3-mhp1/broken-out-2.6.11-rc3-mhp1.tar.gz Or, I could always post the whole bunch to lhms. Nobody there should mind too much. :) The largest part of porting hot-add to a new architecture is usually the sparsemem portion. You'll pretty much have to #ifdef pfn_to_page() and friends, declare a few macros, and then do a bit of debugging. Here's ppc64 as an example: http://www.sr71.net/patches/2.6.11/2.6.11-rc3-mhp1/broken-out/B-sparse-170-sparsemem-ppc64.patch -- Dave - 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/