From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 315326B0044 for ; Wed, 28 Oct 2009 04:31:48 -0400 (EDT) Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate1.de.ibm.com (8.13.1/8.13.1) with ESMTP id n9S8VdV6006909 for ; Wed, 28 Oct 2009 08:31:42 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n9S8Vdm7626706 for ; Wed, 28 Oct 2009 09:31:39 +0100 Received: from d12av02.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n9S8VcpN032645 for ; Wed, 28 Oct 2009 09:31:39 +0100 Date: Wed, 28 Oct 2009 09:31:38 +0100 From: Heiko Carstens Subject: Re: [PATCH v2 1/5] mm: add numa node symlink for memory section in sysfs Message-ID: <20091028083137.GA24140@osiris.boeblingen.de.ibm.com> References: <20091022040814.15705.95572.stgit@bob.kio> <20091022041510.15705.5410.stgit@bob.kio> <20091027195907.GJ14102@ldl.fc.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: Alex Chiang , Andrew Morton , Gary Hade , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Badari Pulavarty , Martin Schwidefsky , Ingo Molnar List-ID: On Tue, Oct 27, 2009 at 02:27:56PM -0700, David Rientjes wrote: > On Tue, 27 Oct 2009, Alex Chiang wrote: > > > Thank you for ACKing, David. > > > > S390 guys, I cc'ed you on this patch because I heard a rumour > > that your memory sections may belong to more than one NUMA node? > > Is that true? If so, how would you like me to handle that > > situation? > > > > You're referring to how unregister_mem_sect_under_nodes() should be > handled, right? register_mem_sect_under_node() already looks supported by > your patch. > > Since the unregister function includes a plural "nodes," I assume that > it's possible for hotplug to register a memory section to more than one > node. That's probably lacking on x86 currently, however, because we lack > node hotplug. > > I'd suggest a similiar iteration through pfn's that the register function > does checking for multiple nodes and then removing the link from all > applicable node_devices kobj when unregistering. > > Maybe one of the s390 maintainers will test that? The short answer is: s390 doesn't support NUMA, because the hardware doesn't tell us to which node (book in s390 terms) a memory range belongs to. Memory layout for a logical partition is striped: first x mbyte belong to node 0, next x mbyte belong to node 1, etc... Also, since there is always a hypervisor running below Linux I don't think it would make too much sense if we would know to which node a piece of memory belongs to: if the hypervisor decides to schedule a virtual cpu of a logical partition to a different node then what? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org