From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FACFC433EF for ; Fri, 12 Nov 2021 02:58:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DE70960C49 for ; Fri, 12 Nov 2021 02:58:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DE70960C49 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 424906B0074; Thu, 11 Nov 2021 21:58:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3CDA76B0078; Thu, 11 Nov 2021 21:58:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 271BF6B007B; Thu, 11 Nov 2021 21:58:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0137.hostedemail.com [216.40.44.137]) by kanga.kvack.org (Postfix) with ESMTP id 0E4656B0074 for ; Thu, 11 Nov 2021 21:58:02 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id BC2FB7CCD0 for ; Fri, 12 Nov 2021 02:58:01 +0000 (UTC) X-FDA: 78798768762.18.D674FBA Received: from out30-45.freemail.mail.aliyun.com (out30-45.freemail.mail.aliyun.com [115.124.30.45]) by imf19.hostedemail.com (Postfix) with ESMTP id 9C761B000182 for ; Fri, 12 Nov 2021 02:57:50 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R671e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0Uw6sOfv_1636685875; Received: from 30.21.164.32(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Uw6sOfv_1636685875) by smtp.aliyun-inc.com(127.0.0.1); Fri, 12 Nov 2021 10:57:56 +0800 Message-ID: <8af6715f-c65b-b73b-f863-2c72ebc8544e@linux.alibaba.com> Date: Fri, 12 Nov 2021 10:58:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH v3] mm: migrate: Support multiple target nodes demotion To: "Huang, Ying" Cc: akpm@linux-foundation.org, dave.hansen@linux.intel.com, ziy@nvidia.com, osalvador@suse.de, shy828301@gmail.com, zhongjiang-ali@linux.alibaba.com, xlpang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <87y25uks84.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Baolin Wang In-Reply-To: <87y25uks84.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 9C761B000182 X-Stat-Signature: 654uxzp8sbwhqidwjbztyy4msnz7fq5g Authentication-Results: imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.45 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-HE-Tag: 1636685870-162456 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2021/11/12 10:44, Huang, Ying wrote: > Baolin Wang writes: > >> We have some machines with multiple memory types like below, which >> have one fast (DRAM) memory node and two slow (persistent memory) memory >> nodes. According to current node demotion policy, if node 0 fills up, >> its memory should be migrated to node 1, when node 1 fills up, its >> memory will be migrated to node 2: node 0 -> node 1 -> node 2 ->stop. >> >> But this is not efficient and suitbale memory migration route >> for our machine with multiple slow memory nodes. Since the distance >> between node 0 to node 1 and node 0 to node 2 is equal, and memory >> migration between slow memory nodes will increase persistent memory >> bandwidth greatly, which will hurt the whole system's performance. >> >> Thus for this case, we can treat the slow memory node 1 and node 2 >> as a whole slow memory region, and we should migrate memory from >> node 0 to node 1 and node 2 if node 0 fills up. >> >> This patch changes the node_demotion data structure to support multiple >> target nodes, and establishes the migration path to support multiple >> target nodes with validating if the node distance is the best or not. >> >> available: 3 nodes (0-2) >> node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 >> node 0 size: 62153 MB >> node 0 free: 55135 MB >> node 1 cpus: >> node 1 size: 127007 MB >> node 1 free: 126930 MB >> node 2 cpus: >> node 2 size: 126968 MB >> node 2 free: 126878 MB >> node distances: >> node 0 1 2 >> 0: 10 20 20 >> 1: 20 10 20 >> 2: 20 20 10 >> >> Signed-off-by: Baolin Wang snip >> /* >> * 'next_pass' contains nodes which became migration >> @@ -3192,6 +3281,14 @@ static int __init migrate_on_reclaim_init(void) >> { >> int ret; >> >> + /* >> + * Ignore allocation failure, if this kmalloc fails >> + * at boot time, we are likely in bigger trouble. >> + */ >> + node_demotion = kmalloc_array(nr_node_ids, >> + sizeof(struct demotion_nodes), >> + GFP_KERNEL); >> + > > I think we should WARN_ON() here. In this unlikey case, I think the mm core will print more information, IMHO WARN_ON() will help little. Anyway no strong opinion on this. Other than that, can I get your reviewed-by tag with this nit fixed? Thanks.