Re: [RFC][PATCH v2 00/21] PMEM NUMA node and hotness accounting/migration

From: Michal Hocko
Date: Fri Dec 28 2018 - 07:22:40 EST

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