From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: CONFIG_ACPI_HOTPLUG_MEMORY=m with x86_64 devel tree Date: 23 Mar 2006 03:43:06 +0100 Message-ID: <20060323024306.GA90581@muc.de> References: <20060321222332.1a037c8e.akpm@osdl.org> <20060322192804.E490.Y-GOTO@jp.fujitsu.com> <20060322030208.30e3581e.akpm@osdl.org> <20060322203220.6433e697.kamezawa.hiroyu@jp.fujitsu.com> <20060322192134.GA44212@muc.de> <20060323082732.9828ca2f.kamezawa.hiroyu@jp.fujitsu.com> <20060323000759.GB71469@muc.de> <20060323093609.8eb03249.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from colin.muc.de ([193.149.48.1]:59910 "EHLO mail.muc.de") by vger.kernel.org with ESMTP id S964908AbWCWCnO (ORCPT ); Wed, 22 Mar 2006 21:43:14 -0500 Date: Thu, 23 Mar 2006 03:43:06 +0100 Content-Disposition: inline In-Reply-To: <20060323093609.8eb03249.kamezawa.hiroyu@jp.fujitsu.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: KAMEZAWA Hiroyuki Cc: akpm@osdl.org, y-goto@jp.fujitsu.com, linux-acpi@vger.kernel.org, tony.luck@intel.com On Thu, Mar 23, 2006 at 09:36:09AM +0900, KAMEZAWA Hiroyuki wrote: > On 23 Mar 2006 01:07:59 +0100 > Andi Kleen wrote: > > > On Thu, Mar 23, 2006 at 08:27:32AM +0900, KAMEZAWA Hiroyuki wrote: > > > On 22 Mar 2006 20:21:34 +0100 > > > Andi Kleen wrote: > > > > > > > > It includes add-new-zone/rebuild-zonelist...etc patches, which will be necessary > > > > > also for x86_64, even if it's not NUMA. > > > > > > > > Hmm? x86_64 supports NUMA systems. > > > > > > > Ah, I know. > > > I wrote "even if.." just because we cannot reserve mem_map for not exisiting node. > > > > Hmm actually I haven't tested it but in theory the reserve hotplug > > code should just work if you list the new nodes already in SRAT as empty > > hotplug PXMs. > > > SRAT is required by Microsoft, then most of servers will equip it, I think. > And SRAT just tells each cpu's/memory range's a pxm. > > But allocating memmap for SRAT entry has some problem in big system. > > For example, our server (ia64/Fujitsu PrimeQuest) can equip memory from > 4G to 1T(maybe 2T in future), and SRAT will *always* say we have possible 1T memory. > (Microsoft requires "write all possible memory in SRAT") > When we reserve memmap for possible 1T memory, Linux will not work well in minimum 4G Don't do that. The x86-64 kernel will preallocate memmaps when everything is enabled soon. Ok that won't concern your IA64 machine immediately. > > Ok there is no code yet to add hotplug cpus to specific nodes later > > but that would be easy to add. > > > We found hot-add-memory-less-node problem now. So, "cpu hot add to a new node" > will be supported later. Again should be pretty easy. -Andi