From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034504AbdEYG2M (ORCPT ); Thu, 25 May 2017 02:28:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:56528 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1031086AbdEYG2K (ORCPT ); Thu, 25 May 2017 02:28:10 -0400 Date: Thu, 25 May 2017 08:28:08 +0200 From: Michal Hocko To: Reza Arbab 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 Subject: Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline Message-ID: <20170525062808.GE12721@dhcp22.suse.cz> References: <20170524122411.25212-1-mhocko@kernel.org> <20170524122411.25212-2-mhocko@kernel.org> <20170524215056.h4r3sdk23bn4c2sr@arbab-laptop.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170524215056.h4r3sdk23bn4c2sr@arbab-laptop.localdomain> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 24-05-17 16:50:56, Reza Arbab wrote: > 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. I am glad to hear that and more is to come. > Acked-by: Reza Arbab Thanks! -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 43F306B0292 for ; Thu, 25 May 2017 02:28:11 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id 10so41014452wml.4 for ; Wed, 24 May 2017 23:28:11 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id c40si24269506edb.70.2017.05.24.23.28.09 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 24 May 2017 23:28:10 -0700 (PDT) Date: Thu, 25 May 2017 08:28:08 +0200 From: Michal Hocko Subject: Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline Message-ID: <20170525062808.GE12721@dhcp22.suse.cz> References: <20170524122411.25212-1-mhocko@kernel.org> <20170524122411.25212-2-mhocko@kernel.org> <20170524215056.h4r3sdk23bn4c2sr@arbab-laptop.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170524215056.h4r3sdk23bn4c2sr@arbab-laptop.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Reza Arbab 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 On Wed 24-05-17 16:50:56, Reza Arbab wrote: > 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. I am glad to hear that and more is to come. > Acked-by: Reza Arbab Thanks! -- Michal Hocko SUSE Labs -- 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