Re: [PATCH v5 6/9] mm/demotion: Add support for removing node from demotion memory tiers

[Aneesh Kumar K V]

On 6/8/22 12:29 PM, Ying Huang wrote:
> On Fri, 2022-06-03 at 19:12 +0530, Aneesh Kumar K.V wrote:
> > This patch adds the special string "none" as a supported memtier value
> > that we can use to remove a specific node from being using as demotion target.
> >
> > For ex:
> > :/sys/devices/system/node/node1# cat memtier
> > 1
> > :/sys/devices/system/node/node1# cat ../../memtier/memtier1/nodelist
> > 1-3
> > :/sys/devices/system/node/node1# echo none > memtier
> > :/sys/devices/system/node/node1#
> > :/sys/devices/system/node/node1# cat memtier
> > :/sys/devices/system/node/node1# cat ../../memtier/memtier1/nodelist
> > 2-3
> > :/sys/devices/system/node/node1#
>
> Do you have a practical use case for this?  What kind of memory node
> needs to be removed from memory tiers demotion/promotion?

This came up in our internal discussion. It was mentioned that there is 
a need to skip some slow memory nodes from participating in demotion.

-aneesh