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 0DD20C46475 for ; Thu, 25 Oct 2018 19:44:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB7312082E for ; Thu, 25 Oct 2018 19:44:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB7312082E 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 S1726296AbeJZESv (ORCPT ); Fri, 26 Oct 2018 00:18:51 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41252 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725784AbeJZESv (ORCPT ); Fri, 26 Oct 2018 00:18:51 -0400 Received: from localhost.localdomain (c-24-4-154-175.hsd1.ca.comcast.net [24.4.154.175]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 886451B52; Thu, 25 Oct 2018 19:44:43 +0000 (UTC) Date: Thu, 25 Oct 2018 12:44:42 -0700 From: Andrew Morton To: Michal Hocko Cc: Roman Gushchin , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Kernel Team , Rik van Riel , Randy Dunlap , Sasha Levin Subject: Re: [RFC PATCH] mm: don't reclaim inodes with many attached pages Message-Id: <20181025124442.5513d282273786369bbb7460@linux-foundation.org> In-Reply-To: <20181025092352.GP18839@dhcp22.suse.cz> References: <20181023164302.20436-1-guro@fb.com> <20181024151950.36fe2c41957d807756f587ca@linux-foundation.org> <20181025092352.GP18839@dhcp22.suse.cz> X-Mailer: Sylpheed 3.5.1 (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 Thu, 25 Oct 2018 11:23:52 +0200 Michal Hocko wrote: > On Wed 24-10-18 15:19:50, Andrew Morton wrote: > > 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. > > > > Is this regression serious enough to warrant fixing 4.19.1? > > Let's not forget about stable tree(s) which backported 172b06c32b94. I > would suggest reverting there. Yup. Sasha, can you please take care of this?