Re: [v2 RFC PATCH 0/9] Another Approach to Use PMEM as NUMA Node

From: Michal Hocko
Date: Tue Apr 16 2019 - 10:40:03 EST

On Tue 16-04-19 07:30:20, Dave Hansen wrote:
> On 4/16/19 12:47 AM, Michal Hocko wrote:
> > You definitely have to follow policy. You cannot demote to a node which
> > is outside of the cpuset/mempolicy because you are breaking contract
> > expected by the userspace. That implies doing a rmap walk.
> What *is* the contract with userspace, anyway? :)
> Obviously, the preferred policy doesn't have any strict contract.
> The strict binding has a bit more of a contract, but it doesn't prevent
> swapping.

Yes, but swapping is not a problem for using binding for memory

> Strict binding also doesn't keep another app from moving the
> memory.

I would consider that a bug.
Michal Hocko