From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa0-f54.google.com (mail-oa0-f54.google.com [209.85.219.54]) by kanga.kvack.org (Postfix) with ESMTP id A32FA6B0035 for ; Tue, 11 Mar 2014 15:56:54 -0400 (EDT) Received: by mail-oa0-f54.google.com with SMTP id n16so9177529oag.13 for ; Tue, 11 Mar 2014 12:56:54 -0700 (PDT) Received: from e34.co.us.ibm.com (e34.co.us.ibm.com. [32.97.110.152]) by mx.google.com with ESMTPS id f4si22418564oel.27.2014.03.11.12.56.53 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 11 Mar 2014 12:56:54 -0700 (PDT) Received: from /spool/local by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Mar 2014 13:56:53 -0600 Received: from b03cxnp07028.gho.boulder.ibm.com (b03cxnp07028.gho.boulder.ibm.com [9.17.130.15]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id 0796B3E40048 for ; Tue, 11 Mar 2014 13:56:51 -0600 (MDT) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by b03cxnp07028.gho.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s2BJuCIS51314724 for ; Tue, 11 Mar 2014 20:56:12 +0100 Received: from d03av02.boulder.ibm.com (localhost [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s2BJunCY011433 for ; Tue, 11 Mar 2014 13:56:50 -0600 Date: Tue, 11 Mar 2014 12:56:33 -0700 From: Nishanth Aravamudan Subject: Node 0 not necessary for powerpc? Message-ID: <20140311195632.GA946@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linuxppc-dev@lists.ozlabs.org, anton@samba.org, rientjes@google.com, cl@linux.com, benh@kernel.crashing.org I have a P7 system that has no node0, but a node0 shows up in numactl --hardware, which has no cpus and no memory (and no PCI devices): numactl --hardware available: 4 nodes (0-3) node 0 cpus: node 0 size: 0 MB node 0 free: 0 MB node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 node 1 size: 0 MB node 1 free: 0 MB node 2 cpus: node 2 size: 7935 MB node 2 free: 7716 MB node 3 cpus: node 3 size: 8395 MB node 3 free: 8015 MB node distances: node 0 1 2 3 0: 10 20 10 20 1: 20 10 20 20 2: 10 20 10 20 3: 20 20 20 10 This is because we statically initialize N_ONLINE to be [0] in mm/page_alloc.c: [N_ONLINE] = { { [0] = 1UL } }, I'm not sure what the architectural requirements are here, but at least on this test system, removing this initialization, it boots fine and is running. I've not yet tried stress tests, but it's survived the beginnings of kernbench so far. numactl --hardware available: 3 nodes (1-3) node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 node 1 size: 0 MB node 1 free: 0 MB node 2 cpus: node 2 size: 7935 MB node 2 free: 7479 MB node 3 cpus: node 3 size: 8396 MB node 3 free: 8375 MB node distances: node 1 2 3 1: 10 20 20 2: 20 10 20 3: 20 20 10 Perhaps we could put in a ARCH_DOES_NOT_NEED_NODE0 and only define it on powerpc for now, conditionalizing the above initialization on that? Thanks, Nish -- 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