Re: [RFC 0/8] Define coherent device memory node

From: Dave Hansen
Date: Mon Oct 24 2016 - 14:04:53 EST


On 10/23/2016 09:31 PM, Anshuman Khandual wrote:
> To achieve seamless integration between system RAM and coherent
> device memory it must be able to utilize core memory kernel features like
> anon mapping, file mapping, page cache, driver managed pages, HW poisoning,
> migrations, reclaim, compaction, etc.

So, you need to support all these things, but not autonuma or hugetlbfs?
What's the reasoning behind that?

If you *really* don't want a "cdm" page to be migrated, then why isn't
that policy set on the VMA in the first place? That would keep "cdm"
pages from being made non-cdm. And, why would autonuma ever make a
non-cdm page and migrate it in to cdm? There will be no NUMA access
faults caused by the devices that are fed to autonuma.

I'm confused.