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=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 DD17BC282DA for ; Wed, 17 Apr 2019 16:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F3C120652 for ; Wed, 17 Apr 2019 16:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555519155; bh=Q/3gqaZqv4SV/BVu2wczug/fGUeCzBxmiB3zH+pv7q8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=n9lEdecAgmBDiVJzZvU//Qf2SnpMaINvQ9JkUr4/GMo+FVf6RV4C1km/NLdn/qKXq OAG59C66gJdgzkWCAeEWcXzvJmxTDXK0lJxdXZ0SKX6Dyc6LzdZ8wl9yDhS1xyAeO1 187E/ttGiPN51FLlHHO51DAor5XegG+Oq+ZcTnpQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732844AbfDQQjO (ORCPT ); Wed, 17 Apr 2019 12:39:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:54726 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729641AbfDQQjO (ORCPT ); Wed, 17 Apr 2019 12:39:14 -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 A99A9B113; Wed, 17 Apr 2019 16:39:12 +0000 (UTC) Date: Wed, 17 Apr 2019 18:39:11 +0200 From: Michal Hocko To: Keith Busch Cc: Dave Hansen , Yang Shi , mgorman@techsingularity.net, riel@surriel.com, hannes@cmpxchg.org, akpm@linux-foundation.org, dan.j.williams@intel.com, fengguang.wu@intel.com, fan.du@intel.com, ying.huang@intel.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v2 RFC PATCH 0/9] Another Approach to Use PMEM as NUMA Node Message-ID: <20190417163911.GA9523@dhcp22.suse.cz> References: <1554955019-29472-1-git-send-email-yang.shi@linux.alibaba.com> <20190412084702.GD13373@dhcp22.suse.cz> <20190416074714.GD11561@dhcp22.suse.cz> <876768ad-a63a-99c3-59de-458403f008c4@linux.alibaba.com> <20190417092318.GG655@dhcp22.suse.cz> <20190417152345.GB4786@localhost.localdomain> <20190417153923.GO5878@dhcp22.suse.cz> <20190417153739.GD4786@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190417153739.GD4786@localhost.localdomain> 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 Wed 17-04-19 09:37:39, Keith Busch wrote: > On Wed, Apr 17, 2019 at 05:39:23PM +0200, Michal Hocko wrote: > > On Wed 17-04-19 09:23:46, Keith Busch wrote: > > > On Wed, Apr 17, 2019 at 11:23:18AM +0200, Michal Hocko wrote: > > > > On Tue 16-04-19 14:22:33, Dave Hansen wrote: > > > > > Keith Busch had a set of patches to let you specify the demotion order > > > > > via sysfs for fun. The rules we came up with were: > > > > > > > > I am not a fan of any sysfs "fun" > > > > > > I'm hung up on the user facing interface, but there should be some way a > > > user decides if a memory node is or is not a migrate target, right? > > > > Why? Or to put it differently, why do we have to start with a user > > interface at this stage when we actually barely have any real usecases > > out there? > > The use case is an alternative to swap, right? The user has to decide > which storage is the swap target, so operating in the same spirit. I do not follow. If you use rebalancing you can still deplete the memory and end up in a swap storage. If you want to reclaim/swap rather than rebalance then you do not enable rebalancing (by node_reclaim or similar mechanism). -- Michal Hocko SUSE Labs