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 6ED2FC433EF for ; Thu, 11 Nov 2021 11:19:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C0CE61058 for ; Thu, 11 Nov 2021 11:19:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233113AbhKKLWU (ORCPT ); Thu, 11 Nov 2021 06:22:20 -0500 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:43530 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229668AbhKKLWQ (ORCPT ); Thu, 11 Nov 2021 06:22:16 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R861e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0Uw1sEVC_1636629565; Received: from 30.21.164.4(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Uw1sEVC_1636629565) by smtp.aliyun-inc.com(127.0.0.1); Thu, 11 Nov 2021 19:19:26 +0800 Subject: Re: [PATCH v2 2/2] mm: migrate: Allocate the node_demotion structure dynamically 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: <87pmr7m5wo.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Baolin Wang Message-ID: Date: Thu, 11 Nov 2021 19:20:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <87pmr7m5wo.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/11/11 16:51, Huang, Ying wrote: > Baolin Wang writes: > >> For the worst case (MAX_NUMNODES=1024), the node_demotion structure can >> consume 32k bytes, which appears too large, so we can change to allocate >> node_demotion dynamically at initialization time. Meanwhile allocating >> the target demotion nodes array dynamically to select a suitable size >> according to the MAX_NUMNODES. >> >> Signed-off-by: Baolin Wang >> --- >> mm/migrate.c | 38 +++++++++++++++++++++++++++++--------- >> 1 file changed, 29 insertions(+), 9 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 126e9e6..0145b38 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1152,10 +1152,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage, >> #define DEFAULT_DEMOTION_TARGET_NODES 15 >> struct demotion_nodes { >> unsigned short nr; >> - short nodes[DEFAULT_DEMOTION_TARGET_NODES]; >> + short nodes[]; >> }; >> >> -static struct demotion_nodes node_demotion[MAX_NUMNODES] __read_mostly; >> +static struct demotion_nodes *node_demotion[MAX_NUMNODES] __read_mostly; >> +static unsigned short target_nodes_max; > > I think we can use something as below, > > #if MAX_NUMNODES < DEFAULT_DEMOTION_TARGET_NODES > #define DEMOTION_TARGET_NODES (MAX_NUMNODES - 1) > #else > #define DEMOTION_TARGET_NODES DEFAULT_DEMOTION_TARGET_NODES > #endif Yes, looks better. > > static struct demotion_nodes *node_demotion; > > Then we can allocate nr_node_ids * sizeof(struct demotion_nodes) for node_demotion. Yeah, this is simple. The reason I want to declare the structure like "struct demotion_nodes *node_demotion[MAX_NUMNODES]" is that, we can validate the non-possible nodes which are invalid to demote memory, and in case the node_demotion[nid] is failed to be allocated which can be validated, though this is unlikely. However, I agree with you to keep things simple now and can be merged into patch 1. Will do in next version. Thanks.