Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752051AbdFNNlO (ORCPT ); Wed, 14 Jun 2017 09:41:14 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:59843 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751869AbdFNNlL (ORCPT ); Wed, 14 Jun 2017 09:41:11 -0400 Subject: Re: RESEND Re: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc To: Balbir Singh Cc: Michael Ellerman , Reza Arbab , "linux-kernel@vger.kernel.org" , Paul Mackerras , "Aneesh Kumar K.V" , Bharata B Rao , Shailendra Singh , Thomas Gleixner , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , Sebastian Andrzej Siewior , Michael Bringmann from Kernel Team References: <3bb44d92-b2ff-e197-4bdf-ec6d588d6dab@linux.vnet.ibm.com> <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> <20170526143147.z4lmtrs7vowucbkf@arbab-laptop.localdomain> <87lgpg6xe2.fsf@concordia.ellerman.id.au> <54877b2b-8446-20f6-e316-25af809ae11f@linux.vnet.ibm.com> <87tw402go0.fsf@concordia.ellerman.id.au> <54ebacf1-1249-cc6a-80a5-b293e581f401@linux.vnet.ibm.com> <8760g9qwfd.fsf@concordia.ellerman.id.au> <87tw3sdmpj.fsf@concordia.ellerman.id.au> <87o9tsgo9b.fsf@concordia.ellerman.id.au> From: Michael Bringmann Organization: IBM Linux Technology Center Date: Wed, 14 Jun 2017 08:41:03 -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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17061413-0008-0000-0000-000008046CA1 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007230; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00874669; UDB=6.00435409; IPR=6.00654757; BA=6.00005421; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015821; XFM=3.00000015; UTC=2017-06-14 13:41:07 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17061413-0009-0000-0000-0000429D2F82 Message-Id: <26b88035-b377-a594-0b7b-cfcf25e43e57@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-14_03:,, 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-1706140230 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2036 Lines: 75 Hello: On 06/14/2017 12:27 AM, Balbir Singh wrote: > On Wed, Jun 14, 2017 at 3:25 PM, Balbir Singh wrote: >> >> >> On Wed, Jun 14, 2017 at 8:21 AM, Michael Bringmann >> wrote: >>> >>> On a related note, we are discussing the addition of 2 new device-tree >>> properties >>> with Pete Heyrman and his fellows that should simplify the determination >>> of the >>> set of required nodes. >>> >>> * One property would provide the total/max number of nodes needed by the >>> kernel >>> on the current hardware. >> >> > > Yes, that would be nice to have > >> >>> >>> * A second property would provide the total/max number of nodes that the >>> kernel >>> could use on any system to which it could be migrated. >>> >> > > Not sure about this one, are you suggesting more memory can be added > depending on the migration target? We would use only one of these numbers to allocate nodes. I have only been on the periphery of the discussions, so I can not communicate the full reasoning as to why both measures would be needed. We would like to have the first number for node allocation/initialization, but if only the second value were provided, we would likely need to use it. >> >> >>> >>> These properties aren't available, yet, and it takes time to define new >>> properties >>> in the PAPR and have them implemented in pHyp and the kernel. As an >>> intermediary >>> step, the systems which are doing a lot of dynamic hot-add/hot-remove >>> configuration >>> could provide equivalent information to the PowerPC kernel with a command >>> line >>> parameter. The 'numa.c' code would then read this value and fill in the >>> necessary >>> entries in the 'node_possible_map'. >>> >>> Would you foresee any problems with using such a feature? >> >> > > Sorry my mailer goofed up, resending > > Balbir Singh > Thanks. -- 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