linux-kernel - Re: [HMM 00/15] HMM (Heterogeneous Memory Management) v22

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Message-ID: <20170524175349.GB24024@redhat.com>
Date:   Wed, 24 May 2017 13:53:50 -0400
From:   Jerome Glisse <jglisse@...hat.com>
To:     Balbir Singh <bsingharora@...il.com>
Cc:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        John Hubbard <jhubbard@...dia.com>,
        David Nellans <dnellans@...dia.com>
Subject: Re: [HMM 00/15] HMM (Heterogeneous Memory Management) v22

On Wed, May 24, 2017 at 11:55:12AM +1000, Balbir Singh wrote:
> On Tue, May 23, 2017 at 2:51 AM, Jérôme Glisse <jglisse@...hat.com> wrote:
> > Patchset is on top of mmotm mmotm-2017-05-18, git branch:
> >
> > https://cgit.freedesktop.org/~glisse/linux/log/?h=hmm-v22
> >
> > Change since v21 is adding back special refcounting in put_page() to
> > catch when a ZONE_DEVICE page is free (refcount going from 2 to 1
> > unlike regular page where a refcount of 0 means the page is free).
> > See patch 8 of this serie for this refcounting. I did not use static
> > keys because it kind of scares me to do that for an inline function.
> > If people strongly feel about this i can try to make static key works
> > here. Kirill will most likely want to review this.
> >
> >
> > Everything else is the same. Below is the long description of what HMM
> > is about and why. At the end of this email i describe briefly each patch
> > and suggest reviewers for each of them.
> >
> >
> > Heterogeneous Memory Management (HMM) (description and justification)
> >
> 
> Thanks for the patches! These patches are very helpful. There are a
> few additional things we would need on top of this (once HMM the base
> is merged)
> 
> 1. Support for other architectures, we'd like to make sure we can get
> this working for powerpc for example. As a first step we have
> ZONE_DEVICE enablement patches, but I think we need some additional
> patches for iomem space searching and memory hotplug, IIRC
> 2. HMM-CDM and physical address based migration bits. In a recent RFC
> we decided to try and use the HMM CDM route as a route to implementing
> coherent device memory as a starting point. It would be nice to have
> those patches on top of these once these make it to mm -
> https://lwn.net/Articles/720380/
> 

I intend to post the updated HMM CDM patchset early next week. I am
tie in couple internal backport but i should be able to resume work
on that this week.

Cheers,
Jérôme