From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161492AbdEXVvH (ORCPT ); Wed, 24 May 2017 17:51:07 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:47399 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1033549AbdEXVvG (ORCPT ); Wed, 24 May 2017 17:51:06 -0400 Date: Wed, 24 May 2017 16:50:56 -0500 From: Reza Arbab To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Jerome Glisse , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Andi Kleen , David Rientjes , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko Subject: Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline References: <20170524122411.25212-1-mhocko@kernel.org> <20170524122411.25212-2-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20170524122411.25212-2-mhocko@kernel.org> Organization: IBM Linux Technology Center User-Agent: NeoMutt/20170428 (1.8.2) X-TM-AS-GCONF: 00 x-cbid: 17052421-0016-0000-0000-000006D02A33 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007112; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00865137; UDB=6.00429544; IPR=6.00644918; BA=6.00005372; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015571; XFM=3.00000015; UTC=2017-05-24 21:51:03 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17052421-0017-0000-0000-000039CBA85C Message-Id: <20170524215056.h4r3sdk23bn4c2sr@arbab-laptop.localdomain> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-24_15:,, 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-1705240120 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 24, 2017 at 02:24:10PM +0200, Michal Hocko wrote: >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL >memory") has added can_offline_normal which checks the amount of >memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable. >It disallows to offline memory if there is nothing left with a >justification that "memory-management acts bad when we have nodes which >is online but don't have any normal memory". > >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL >memory") has introduced a restriction that every numa node has to have >at least some memory in !movable zones before a first movable memory >can be onlined if !CONFIG_MOVABLE_NODE with the same justification > >While it is true that not having _any_ memory for kernel allocations on >a NUMA node is far from great and such a node would be quite subotimal >because all kernel allocations will have to fallback to another NUMA >node but there is no reason to disallow such a configuration in >principle. > >Besides that there is not really a big difference to have one memblock >for ZONE_NORMAL available or none. With 128MB size memblocks the system >might trash on the kernel allocations requests anyway. It is really >hard to draw a line on how much normal memory is really sufficient so >we have to rely on administrator to configure system sanely therefore >drop the artificial restriction and remove can_offline_normal and >can_online_high_movable altogether. I'm really liking all this cleanup of the memory hotplug code. Thanks! Much appreciated. Acked-by: Reza Arbab -- Reza Arbab From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id E0E596B0279 for ; Wed, 24 May 2017 17:51:06 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id p74so205775110pfd.11 for ; Wed, 24 May 2017 14:51:06 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id e3si7452770plk.67.2017.05.24.14.51.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 May 2017 14:51:06 -0700 (PDT) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v4OLn212125222 for ; Wed, 24 May 2017 17:51:05 -0400 Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) by mx0a-001b2d01.pphosted.com with ESMTP id 2anh76jn65-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 24 May 2017 17:51:05 -0400 Received: from localhost by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 24 May 2017 15:51:04 -0600 Date: Wed, 24 May 2017 16:50:56 -0500 From: Reza Arbab Subject: Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline References: <20170524122411.25212-1-mhocko@kernel.org> <20170524122411.25212-2-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20170524122411.25212-2-mhocko@kernel.org> Message-Id: <20170524215056.h4r3sdk23bn4c2sr@arbab-laptop.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Jerome Glisse , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Andi Kleen , David Rientjes , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko On Wed, May 24, 2017 at 02:24:10PM +0200, Michal Hocko wrote: >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL >memory") has added can_offline_normal which checks the amount of >memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable. >It disallows to offline memory if there is nothing left with a >justification that "memory-management acts bad when we have nodes which >is online but don't have any normal memory". > >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL >memory") has introduced a restriction that every numa node has to have >at least some memory in !movable zones before a first movable memory >can be onlined if !CONFIG_MOVABLE_NODE with the same justification > >While it is true that not having _any_ memory for kernel allocations on >a NUMA node is far from great and such a node would be quite subotimal >because all kernel allocations will have to fallback to another NUMA >node but there is no reason to disallow such a configuration in >principle. > >Besides that there is not really a big difference to have one memblock >for ZONE_NORMAL available or none. With 128MB size memblocks the system >might trash on the kernel allocations requests anyway. It is really >hard to draw a line on how much normal memory is really sufficient so >we have to rely on administrator to configure system sanely therefore >drop the artificial restriction and remove can_offline_normal and >can_online_high_movable altogether. I'm really liking all this cleanup of the memory hotplug code. Thanks! Much appreciated. Acked-by: Reza Arbab -- Reza Arbab -- 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