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

Michal Hocko
2019-04-16T14:40:03Z

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
partitioning.

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

I would consider that a bug.
--
Michal Hocko
SUSE Labs