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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 264EAC0044C for ; Mon, 5 Nov 2018 04:59:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C0F82082A for ; Mon, 5 Nov 2018 04:59:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C0F82082A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729034AbeKEORF (ORCPT ); Mon, 5 Nov 2018 09:17:05 -0500 Received: from relay.sw.ru ([185.231.240.75]:37394 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728165AbeKEORF (ORCPT ); Mon, 5 Nov 2018 09:17:05 -0500 Received: from [172.16.24.21] by relay.sw.ru with esmtp (Exim 4.90_1) (envelope-from ) id 1gJWyn-0006f6-VF; Mon, 05 Nov 2018 07:59:14 +0300 Subject: Re: [PATCH 1/2] mm: use kvzalloc for swap_info_struct allocation To: "Huang, Ying" Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Aaron Lu References: <37b60523-d085-71e9-fef9-80b90bfcef18@virtuozzo.com> <87wopsbb5v.fsf@yhuang-dev.intel.com> From: Vasily Averin Message-ID: Date: Mon, 5 Nov 2018 07:59:13 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <87wopsbb5v.fsf@yhuang-dev.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/5/18 3:50 AM, Huang, Ying wrote: > Vasily Averin writes: > >> commit a2468cc9bfdf ("swap: choose swap device according to numa node") >> increased size of swap_info_struct up to 44 Kbytes, now it requires >> 4th order page. > > Why swap_info_struct could be so large? Because MAX_NUMNODES could be > thousands so that 'avail_lists' field could be tens KB? If so, I think > it's fair to use kvzalloc(). Can you add one line comment? Because > struct swap_info_struct is quite small in default configuration. I was incorrect not 44Kb but 40kb should be here. We have found CONFIG_NODES_SHIFT=10 in new RHEL7 update 6 kernel, default ubuntu kernels have the same setting too. crash> struct swap_info_struct -o struct swap_info_struct { [0] unsigned long flags; [8] short prio; ... [140] spinlock_t lock; [144] struct plist_node list; [184] struct plist_node avail_lists[1024]; <<<< here [41144] struct swap_cluster_info *cluster_info; [41152] struct swap_cluster_list free_clusters; ... [41224] spinlock_t cont_lock; } SIZE: 41232 struct swap_info_struct { ... RH_KABI_EXTEND(struct plist_node avail_lists[MAX_NUMNODES]) /* entry in swap_avail_head */ ... } #define MAX_NUMNODES (1 << NODES_SHIFT) #ifdef CONFIG_NODES_SHIFT #define NODES_SHIFT CONFIG_NODES_SHIFT #else #define NODES_SHIFT 0 #endif /boot/config-4.15.0-38-generic:CONFIG_NODES_SHIFT=10