Re: [RFC PATCH v2 0/3] mm/damon: Introduce node_target_mem_bp Quota Goal Metric

SeongJae Park
2026-01-31T19:54:18Z

On Thu, 29 Jan 2026 17:48:06 -0800 SeongJae Park <sj@kernel.org> wrote:

> On Thu, 29 Jan 2026 13:58:11 -0800 Ravi Jonnalagadda <ravis.opensrc@gmail.com> wrote:
>
> > This series introduces a new DAMON quota goal metric, `node_target_mem_bp`,
> > designed for controlling memory migration in heterogeneous memory systems
> > (e.g., DRAM and CXL memory tiering).
> >
> > v1: https://lore.kernel.org/linux-mm/20260123045733.6954-1-ravis.opensrc@gmail.com/T/#u
[...]
> Context 0: monitors node 0, migrate_hot -> node 1
> goal: node_ineligible_mem_bp, nid=0, target=4000
>
> Context 1: monitors node 1, migrate_hot -> node 0
> goal: node_target_mem_bp, nid=0, target=6000

In offline, Ravi enlightened me that using a single context with two schemes
instead of the above two contexts setup can be more efficienct and useful. I
agree that. It will be able to only single kdamond, and there could be more
flexible use cases that can use the whole-memory access pattern.

That is, we can use single context with the two schemes, but adding a core
layer DAMOS filters for applying the schemes to only memory of node 0 and node
1, respectively. Similar for memory tiering use cases.

But I was recommending the multi contexts approach to people because the
current implementation of DAMOS is not efficient when both quota and core layer
filters are used. I was actually working on making it improved, and just
posted an RFC patch series [1]. After the patches are merged, hopefully the
single context approach will be useful and effcient enough for varying use
cases including the memory tiering.

[1] https://lore.kernel.org/20260131194145.66286-1-sj@kernel.org

Thanks,
SJ …