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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 E1214C282CE for ; Thu, 11 Apr 2019 15:24:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD2B720643 for ; Thu, 11 Apr 2019 15:24:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554996259; bh=6e+pj2aQBoi8rIlYDWkd64W7SDDUShSvGkMhNYazVXE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=SrW9r1aOhwK9QtpyyJQTMpeZLotg+s0qaX1ON1r/JO2kR4PddQX1oLY6bdWzbBnm9 YK9S1w/Pmj8EQi5QrS9D6ypSWklghbsVIxKQOv4LUsmP6Tt7cunIof11vSx2o787Uc Y5yslWb3A8wnupcrqHBhW52+C0mPfl4pgOpPamMc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726828AbfDKPYS (ORCPT ); Thu, 11 Apr 2019 11:24:18 -0400 Received: from mx2.suse.de ([195.135.220.15]:51338 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726121AbfDKPYR (ORCPT ); Thu, 11 Apr 2019 11:24:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 10A4CAD4C; Thu, 11 Apr 2019 15:24:16 +0000 (UTC) Date: Thu, 11 Apr 2019 17:24:15 +0200 From: Michal Hocko To: Waiman Long Cc: Tejun Heo , Li Zefan , Johannes Weiner , Jonathan Corbet , Vladimir Davydov , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Roman Gushchin , Shakeel Butt , Kirill Tkhai , Aaron Lu Subject: Re: [RFC PATCH 0/2] mm/memcontrol: Finer-grained memory control Message-ID: <20190411152415.GA10383@dhcp22.suse.cz> References: <20190410191321.9527-1-longman@redhat.com> <20190410195443.GL10383@dhcp22.suse.cz> <20190411151911.GZ10383@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190411151911.GZ10383@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 11-04-19 17:19:11, Michal Hocko wrote: > On Thu 11-04-19 10:02:16, Waiman Long wrote: > > On 04/10/2019 03:54 PM, Michal Hocko wrote: > > > On Wed 10-04-19 15:13:19, Waiman Long wrote: > > >> The current control mechanism for memory cgroup v2 lumps all the memory > > >> together irrespective of the type of memory objects. However, there > > >> are cases where users may have more concern about one type of memory > > >> usage than the others. > > >> > > >> We have customer request to limit memory consumption on anonymous memory > > >> only as they said the feature was available in other OSes like Solaris. > > > Please be more specific about a usecase. > > > > From that customer's point of view, page cache is more like common goods > > that can typically be shared by a number of different groups. Depending > > on which groups touch the pages first, it is possible that most of those > > pages can be disproportionately attributed to one group than the others. > > Anonymous memory, on the other hand, are not shared and so can more > > correctly represent the memory footprint of an application. Of course, > > there are certainly cases where an application can have large private > > files that can consume a lot of cache pages. These are probably not the > > case for the applications used by that customer. > > So you are essentially interested in the page cache limiting, right? > This has been proposed several times already and always rejected because > this is not a good idea. OK, so after reading other responses I've realized that I've misunderstood your intention. You are really interested in the anon memory limiting. But my objection still holds! I would like to hear much more specific usecases. Is the page cache such a precious resource it cannot be refaulted? With the storage speed these days I am quite not sure. Also there is always way to delegate page cache pre-faulting to a dedicated cgroup with a low limit protection if _some_ pagecache is really important. -- Michal Hocko SUSE Labs