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Date:   Fri, 28 Dec 2018 13:15:15 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Fengguang Wu <fengguang.wu@intel.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        kvm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Fan Du <fan.du@intel.com>, Yao Yuan <yuan.yao@intel.com>,
        Peng Dong <dongx.peng@intel.com>,
        Huang Ying <ying.huang@intel.com>,
        Liu Jingqi <jingqi.liu@intel.com>,
        Dong Eddie <eddie.dong@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Zhang Yi <yi.z.zhang@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>
Subject: Re: [RFC][PATCH v2 00/21] PMEM NUMA node and hotness
 accounting/migration
Message-ID: <20181228121515.GS16738@dhcp22.suse.cz>
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On Fri 28-12-18 17:42:08, Wu Fengguang wrote:
[...]
> Those look unnecessary complexities for this post. This v2 patchset
> mainly fulfills our first milestone goal: a minimal viable solution
> that's relatively clean to backport. Even when preparing for new
> upstreamable versions, it may be good to keep it simple for the
> initial upstream inclusion.

On the other hand this is creating a new NUMA semantic and I would like
to have something long term thatn let's throw something in now and care
about long term later. So I would really prefer to talk about long term
plans first and only care about implementation details later.

> > I haven't looked at the implementation yet but if you are proposing a
> > special cased zone lists then this is something CDM (Coherent Device
> > Memory) was trying to do two years ago and there was quite some
> > skepticism in the approach.
> 
> It looks we are pretty different than CDM. :)
> We creating new NUMA nodes rather than CDM's new ZONE.
> The zonelists modification is just to make PMEM nodes more separated.

Yes, this is exactly what CDM was after. Have a zone which is not
reachable without explicit request AFAIR. So no, I do not think you are
too different, you just use a different terminology ;)

-- 
Michal Hocko
SUSE Labs