Re: [Ksummit-discuss] ZONE_DEVICE and Persistent Memory (was: Re: Draft agenda for the kernel summit)

[Jerome Glisse <j.glisse@gmail.com>]

On Mon, Oct 19, 2015 at 12:23:47PM -0700, Dan Williams wrote:
> On Mon, Oct 19, 2015 at 11:52 AM, Theodore Ts'o <tytso@mit.edu> wrote:
> > On Mon, Oct 19, 2015 at 02:29:23PM -0400, Theodore Ts'o wrote:
> >> On Fri, Oct 16, 2015 at 05:08:21PM -0400, Jerome Glisse wrote:
> >> > On Thu, Oct 15, 2015 at 09:49:49AM -0700, Dave Hansen wrote:
> >> > > On 10/14/2015 05:17 PM, Dan Williams wrote:
> >> > > > I am wondering if it would be productive / good use of time to do a
> >> > > > direction check on the mm changes being done in support of large
> >> > > > persistent memory devices.
> >> > >
> >> > > I think there's probably an even wider discussion that we should have here.
> >> > >
> >> > > Beyond just ZONE_DEVICE, the sheer number of memory types is increasing
> >> > > fast, and our current solutions are, at best, inconsistent. We currently
> >> > > handle memory types as new zones, repurposed zones, pageblocks inside
> >> > > zones, or faux NUMA nodes.
> >> > >
> >> > > Are our current solutions too erratic?
> >> > > Do we need to solve these problems generally, or are we going to kill
> >> > > ourselves trying to make everyone happy?
> >> > > What types do we ignore today, but shouldn't?
> >> > > What types are coming down the pike?
> >> >
> >> > I think what i am working on (HMM and how to leverage GPU memory that is
> >> > not accessible by the CPU) apply here too. All features i am working on
> >> > imply that i have to dig through layers of code seeing if i can abuse an
> >> > existing mechanism to achieve something new.
> >> >
> >> > So i definitly think we should discuss where we are and where we want to
> >> > be.
> >>
> >> Dan, would you be willing to kick off the discussion?
> >
> > Oops, sorry, it was pointed out to me that Dan isn't going to be at
> > the Kernel Summit.  Jerome, would you be willing to kick off the
> > discussion and report back to Dan?
> 
> Well, you were right the first time ;-), I'm booked and registered.
> 
> Yes, I'd be willing to kick off the discussion.

I can help keeping the discussion going on :)