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=-7.0 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,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 0DC76C43387 for ; Sat, 22 Dec 2018 01:12:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB3DE21928 for ; Sat, 22 Dec 2018 01:12:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404214AbeLVBMA (ORCPT ); Fri, 21 Dec 2018 20:12:00 -0500 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:47440 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732140AbeLVBMA (ORCPT ); Fri, 21 Dec 2018 20:12:00 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04389;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0TGLpJVy_1545440952; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TGLpJVy_1545440952) by smtp.aliyun-inc.com(127.0.0.1); Sat, 22 Dec 2018 09:09:15 +0800 Subject: Re: [v3 PATCH 1/2] mm: swap: check if swap backing device is congested or not To: Tim Chen , ying.huang@intel.com, tim.c.chen@intel.com, minchan@kernel.org, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1545428420-126557-1-git-send-email-yang.shi@linux.alibaba.com> From: Yang Shi Message-ID: Date: Fri, 21 Dec 2018 17:09:07 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/21/18 2:42 PM, Tim Chen wrote: > On 12/21/18 1:40 PM, Yang Shi wrote: >> Swap readahead would read in a few pages regardless if the underlying >> device is busy or not. It may incur long waiting time if the device is >> congested, and it may also exacerbate the congestion. >> >> Use inode_read_congested() to check if the underlying device is busy or >> not like what file page readahead does. Get inode from swap_info_struct. >> Although we can add inode information in swap_address_space >> (address_space->host), it may lead some unexpected side effect, i.e. >> it may break mapping_cap_account_dirty(). Using inode from >> swap_info_struct seems simple and good enough. >> >> Just does the check in vma_cluster_readahead() since >> swap_vma_readahead() is just used for non-rotational device which >> much less likely has congestion than traditional HDD. >> >> Although swap slots may be consecutive on swap partition, it still may be >> fragmented on swap file. This check would help to reduce excessive stall >> for such case. >> >> Cc: Huang Ying >> Cc: Tim Chen >> Cc: Minchan Kim >> Signed-off-by: Yang Shi >> --- >> v3: Move inode deference under swap device type check per Tim Chen >> v2: Check the swap device type per Tim Chen >> >> mm/swap_state.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/mm/swap_state.c b/mm/swap_state.c >> index fd2f21e..78d500e 100644 >> --- a/mm/swap_state.c >> +++ b/mm/swap_state.c >> @@ -538,11 +538,18 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, >> bool do_poll = true, page_allocated; >> struct vm_area_struct *vma = vmf->vma; >> unsigned long addr = vmf->address; >> + struct inode *inode = NULL; >> >> mask = swapin_nr_pages(offset) - 1; >> if (!mask) >> goto skip; >> >> + if (si->flags & (SWP_BLKDEV | SWP_FS)) { >> + inode = si->swap_file->f_mapping->host; >> + if (inode_read_congested(inode)) >> + goto skip; >> + } >> + >> do_poll = false; >> /* Read a page_cluster sized and aligned cluster around offset. */ >> start_offset = offset & ~mask; >> > Acked-by: Tim Chen Thanks. Happy holiday.