Re: [RFC PATCH 02/14] mm/hms: heterogenenous memory system (HMS) documentation

[Dan Williams]

On Wed, Dec 5, 2018 at 3:27 PM Jerome Glisse <jglisse@xxxxxxxxxx> wrote:
>
> On Wed, Dec 05, 2018 at 04:23:42PM -0700, Logan Gunthorpe wrote:
> >
> >
> > On 2018-12-05 4:20 p.m., Jerome Glisse wrote:
> > > And my proposal is under /sys/bus and have symlink to all existing
> > > device it agregate in there.
> >
> > That's so not the point. Use the existing buses don't invent some
> > virtual tree. I don't know how many times I have to say this or in how
> > many ways. I'm not responding anymore.
>
> And how do i express interaction with different buses because i just
> do not see how to do that in the existing scheme. It would be like
> teaching to each bus about all the other bus versus having each bus
> register itself under a common framework and have all the interaction
> between bus mediated through that common framework avoiding code
> duplication accross buses.
>
> >
> > > So you agree with my proposal ? A sysfs directory in which all the
> > > bus and how they are connected to each other and what is connected
> > > to each of them (device, CPU, memory).
> >
> > I'm fine with the motivation. What I'm arguing against is the
> > implementation and the fact you have to create a whole grand new
> > userspace API and hierarchy to accomplish it.

Right, GPUs show up in /sys today. Don't register a whole new
hierarchy as an alias to what already exists, add a new attribute
scheme to the existing hierarchy. This is what the HMAT enabling is
doing, this is what p2pdma is doing.