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

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

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.

Cheers,
Jérôme