Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 17 Apr 2019 09:37:39 -0600
From:   Keith Busch <keith.busch@intel.com>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Dave Hansen <dave.hansen@intel.com>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        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: <20190417153739.GD4786@localhost.localdomain>
References: <1554955019-29472-1-git-send-email-yang.shi@linux.alibaba.com>
 <20190412084702.GD13373@dhcp22.suse.cz>
 <a68137bb-dcd8-4e4a-b3a9-69a66f9dccaf@linux.alibaba.com>
 <20190416074714.GD11561@dhcp22.suse.cz>
 <876768ad-a63a-99c3-59de-458403f008c4@linux.alibaba.com>
 <a0bf6b61-1ec2-6209-5760-80c5f205d52e@intel.com>
 <20190417092318.GG655@dhcp22.suse.cz>
 <20190417152345.GB4786@localhost.localdomain>
 <20190417153923.GO5878@dhcp22.suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190417153923.GO5878@dhcp22.suse.cz>
User-Agent: Mutt/1.9.1 (2017-09-22)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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.