Re: [PATCH -V11 8/9] mm/vmscan: never demote for memcg reclaim

[Yang Shi]

On Wed, Jul 21, 2021 at 2:58 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>
> On 7/21/21 2:38 PM, Zi Yan wrote:
> > On 21 Jul 2021, at 2:39, Huang Ying wrote:
> >> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> >>
> >> Global reclaim aims to reduce the amount of memory used on a
> >> given node or set of nodes.  Migrating pages to another node
> >> serves this purpose.
> >>
> >> memcg reclaim is different.  Its goal is to reduce the total
> >> memory consumption of the entire memcg, across all nodes.
> >> Migration does not assist memcg reclaim because it just moves
> >> page contents between nodes rather than actually reducing memory
> >> consumption.
> ...
> > Should this be folded into Patch 4 when can_demote() is
> > introduced?
>
> I guess it could be.  But, it's logically separate since it has its
> own justification which is rather discrete.
>
> I think it's best to keep it separate.

Yes, I agree.