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 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 2F440ECDE46 for ; Wed, 24 Oct 2018 22:18:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D19DB2075D for ; Wed, 24 Oct 2018 22:18:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D19DB2075D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org 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 S1726776AbeJYGst (ORCPT ); Thu, 25 Oct 2018 02:48:49 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45936 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726297AbeJYGst (ORCPT ); Thu, 25 Oct 2018 02:48:49 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E55711721; Wed, 24 Oct 2018 22:18:55 +0000 (UTC) Date: Wed, 24 Oct 2018 15:18:53 -0700 From: Andrew Morton To: Roman Gushchin Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Kernel Team , Michal Hocko , Rik van Riel , Randy Dunlap Subject: Re: [RFC PATCH] mm: don't reclaim inodes with many attached pages Message-Id: <20181024151853.3edd9097400b0d52edff1f16@linux-foundation.org> In-Reply-To: <20181023164302.20436-1-guro@fb.com> References: <20181023164302.20436-1-guro@fb.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 23 Oct 2018 16:43:29 +0000 Roman Gushchin wrote: > Spock reported that the commit 172b06c32b94 ("mm: slowly shrink slabs > with a relatively small number of objects") leads to a regression on > his setup: periodically the majority of the pagecache is evicted > without an obvious reason, while before the change the amount of free > memory was balancing around the watermark. > > The reason behind is that the mentioned above change created some > minimal background pressure on the inode cache. The problem is that > if an inode is considered to be reclaimed, all belonging pagecache > page are stripped, no matter how many of them are there. So, if a huge > multi-gigabyte file is cached in the memory, and the goal is to > reclaim only few slab objects (unused inodes), we still can eventually > evict all gigabytes of the pagecache at once. > > The workload described by Spock has few large non-mapped files in the > pagecache, so it's especially noticeable. > > To solve the problem let's postpone the reclaim of inodes, which have > more than 1 attached page. Let's wait until the pagecache pages will > be evicted naturally by scanning the corresponding LRU lists, and only > then reclaim the inode structure. > > ... > > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -730,8 +730,11 @@ static enum lru_status inode_lru_isolate(struct list_head *item, > return LRU_REMOVED; > } > > - /* recently referenced inodes get one more pass */ > - if (inode->i_state & I_REFERENCED) { > + /* > + * Recently referenced inodes and inodes with many attached pages > + * get one more pass. > + */ > + if (inode->i_state & I_REFERENCED || inode->i_data.nrpages > 1) { > inode->i_state &= ~I_REFERENCED; > spin_unlock(&inode->i_lock); > return LRU_ROTATE; hm, why "1"? I guess one could argue that this will encompass long symlinks, but I just made that up to make "1" appear more justifiable ;)