From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752831AbbH0LHc (ORCPT ); Thu, 27 Aug 2015 07:07:32 -0400 Received: from unicom146.biz-email.net ([210.51.26.146]:1348 "EHLO unicom146.biz-email.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751559AbbH0LHa (ORCPT ); Thu, 27 Aug 2015 07:07:30 -0400 Subject: Re: [PATCH V3] mm: memory hot-add: memory can not be added to movable zone defaultly To: Vlastimil Babka , , References: <1440665641-3839-1-git-send-email-liuchangsheng@inspur.com> <55DED890.4020200@suse.cz> CC: , , , , , Changsheng Liu From: Changsheng Liu Message-ID: <55DEEF68.4090403@inspur.com> Date: Thu, 27 Aug 2015 19:07:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <55DED890.4020200@suse.cz> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.165.23.10] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2015/8/27 17:29, Vlastimil Babka 写道: > On 08/27/2015 10:54 AM, Changsheng Liu wrote: >> From: Changsheng Liu >> >> After the user config CONFIG_MOVABLE_NODE and movable_node kernel >> option, >> When the memory is hot added, should_add_memory_movable() return 0 >> because all zones including movable zone are empty, >> so the memory that was hot added will be added to the normal zone >> and the normal zone will be created firstly. >> But we want the whole node to be added to movable zone defaultly. > > OK it seems current behavior indeed goes against the expectations of > setting movable_node. > >> So we change should_add_memory_movable(): if the user config >> CONFIG_MOVABLE_NODE and movable_node kernel option >> it will always return 1 and all zones is empty at the same time, >> so that the movable zone will be created firstly >> and then the whole node will be added to movable zone defaultly. >> If we want the node to be added to normal zone, >> we can do it as follows: >> "echo online_kernel > /sys/devices/system/memory/memoryXXX/state" >> >> If the memory is added to movable zone defaultly, >> the user can offline it and add it to other zone again. > > Was this tested to really work as well? Per Yasuaki's explanation in > v2, you shouldn't create ZONE_MOVABLE before ZONE_NORMAL. We will test it more fully. There is on limit written in Documentation/memory-hotplug.txt when move the memory from movable zone to normal zone: echo online_kernel > /sys/devices/system/memory/memoryXXX/state (NOTE: current limit: this memory block must be adjacent to ZONE_NORMAL) The zone will be created as follows: First,all zones have been initialized,but all zones are empty, then the should_add_memory_movable() return 1 so the movable is created and add the whole node to movable zone. empty whole node's memory |-------------------|-------------------------------|--- ZONE_NORMAL ZONE_MOVABLE when we move the memory to normal zone empty whole node's memory |--------------------|----------------------------------------------------:-------------------------------------------| one memory block ajacent to ZONE_NORMAL : ZONE_NORMAL ZONE_MOVABLE : : one memory block : whole node - one memory block |-------------------------------------------------------------------------|-------------------------------------------| ZONE_NORMAL ZONE_MOVABLE > >> But if the memory is added to normal zone defaultly, >> the user will not offline the memory used by kernel. >> >> Reviewed-by: Andrew Morton > > Interesting... > >> Signed-off-by: Changsheng Liu i >> Tested-by: Dongdong Fan >> --- >> mm/memory_hotplug.c | 3 +++ >> 1 files changed, 3 insertions(+), 0 deletions(-) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index 26fbba7..b5f14fa 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -1198,6 +1198,9 @@ static int should_add_memory_movable(int nid, >> u64 start, u64 size) >> pg_data_t *pgdat = NODE_DATA(nid); >> struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE; >> >> + if (movable_node_is_enabled()) >> + return 1; >> + >> if (zone_is_empty(movable_zone)) >> return 0; >> >> > > . >