From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967884AbdEZMcj (ORCPT ); Fri, 26 May 2017 08:32:39 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41925 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S967646AbdEZMcC (ORCPT ); Fri, 26 May 2017 08:32:02 -0400 Subject: Re: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc To: Michael Ellerman , Reza Arbab , Balbir Singh Cc: linux-kernel@vger.kernel.org, Paul Mackerras , "Aneesh Kumar K.V" , Bharata B Rao , Shailendra Singh , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Sebastian Andrzej Siewior References: <3bb44d92-b2ff-e197-4bdf-ec6d588d6dab@linux.vnet.ibm.com> <20170523155251.bqwc5mc4jpgzkqlm@arbab-laptop.localdomain> <1c1d70e3-4e45-b035-0e75-1b0f531c111b@linux.vnet.ibm.com> <20170523214922.bns675oqzqj4pkhc@arbab-laptop.localdomain> <87poeya4dt.fsf@concordia.ellerman.id.au> <8e2417d8-d108-2949-40f2-997d53a3f367@linux.vnet.ibm.com> <87a861a25y.fsf@concordia.ellerman.id.au> <20170525151011.m4ae4ipxbqsj3mn7@arbab-laptop.localdomain> <87zie08ekt.fsf@concordia.ellerman.id.au> From: Michael Bringmann Organization: IBM Linux Technology Center Date: Fri, 26 May 2017 07:31:51 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: <87zie08ekt.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17052612-2213-0000-0000-000001C6517B X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007120; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00865826; UDB=6.00430008; IPR=6.00645687; BA=6.00005375; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015594; XFM=3.00000015; UTC=2017-05-26 12:31:55 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17052612-2214-0000-0000-000056431BEB Message-Id: <0def3557-7296-916a-f7d5-441cf5f1e00c@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-26_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705260229 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I am running into this problem on PowerPC systems where Balbir's patch set was targeted. So, yes, I do need to be able to add/enable a new numa node during system execution in cases where more resources (memory, virtual processors) are added to the system dynamically. On 05/25/2017 10:46 PM, Michael Ellerman wrote: > Reza Arbab writes: > >> On Thu, May 25, 2017 at 04:19:53PM +1000, Michael Ellerman wrote: >>> The commit message for 3af229f2071f says: >>> >>> In practice, we never see a system with 256 NUMA nodes, and in fact, we >>> do not support node hotplug on power in the first place, so the nodes >>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>> that are online when we come up are the nodes that will be present for >>> the lifetime of this kernel. >>> >>> Is that no longer true? >> >> I don't know what the reasoning behind that statement was at the time, >> but as far as I can tell, the only thing missing for node hotplug now is >> Balbir's patchset [1]. He fixes the resource issue which motivated >> 3af229f2071f and reverts it. >> >> With that set, I can instantiate a new numa node just by doing >> add_memory(nid, ...) where nid doesn't currently exist. > > But does that actually happen on any real system? > > cheers > > -- Michael W. Bringmann Linux Technology Center IBM Corporation Tie-Line 363-5196 External: (512) 286-5196 Cell: (512) 466-0650 mwb@linux.vnet.ibm.com