Re: [RFC PATCH 02/11] mm/damon: add a new DAMOS quota goal metric for cgroup on node memory usage

[SeongJae Park <sj@kernel.org>]

On Thu, 19 Jun 2025 15:00:14 -0700 SeongJae Park <sj@kernel.org> wrote:

> Define a new DAMOS quota auto-tuning target metrics for per-cgroup
> per-node memory usage.  Also extend damos_quota_goal struct to have a
> field for specifying the cgroup of the interest.
> 
> Note that this commit is only for DAMON kernel API extension.  Real
> behavior of the new metric will be implemented by a following commit.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  include/linux/damon.h | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/damon.h b/include/linux/damon.h
> index 39b835dd3c4d..43aef959d357 100644
> --- a/include/linux/damon.h
> +++ b/include/linux/damon.h
> @@ -175,6 +175,7 @@ enum damos_action {
>   * @DAMOS_QUOTA_SOME_MEM_PSI_US:	System level some memory PSI in us.
>   * @DAMOS_QUOTA_NODE_MEM_USED_BP:	MemUsed ratio of a node.
>   * @DAMOS_QUOTA_NODE_MEM_FREE_BP:	MemFree ratio of a node.
> + * @DAMOS_QUOTA_NODE_MEMCG_USED_BP:	MemUsed ratio of a node for a cgroup.
>   * @DAMOS_QUOTA_ACTIVE_MEM_BP:		Active to inactive memory ratio.
>   * @NR_DAMOS_QUOTA_GOAL_METRICS:	Number of DAMOS quota goal metrics.
>   *
> @@ -185,6 +186,7 @@ enum damos_quota_goal_metric {
>  	DAMOS_QUOTA_SOME_MEM_PSI_US,
>  	DAMOS_QUOTA_NODE_MEM_USED_BP,
>  	DAMOS_QUOTA_NODE_MEM_FREE_BP,
> +	DAMOS_QUOTA_NODE_MEMCG_USED_BP,
>  	DAMOS_QUOTA_ACTIVE_MEM_BP,
>  	NR_DAMOS_QUOTA_GOAL_METRICS,
>  };
> @@ -196,6 +198,7 @@ enum damos_quota_goal_metric {
>   * @current_value:	Current value of @metric.
>   * @last_psi_total:	Last measured total PSI
>   * @nid:		Node id.
> + * @memcg:		Memcg id.

The name of the field is not memcg but memcg_id.  I will fix this in the next
version.

>   * @list:		List head for siblings.
>   *
>   * Data structure for getting the current score of the quota tuning goal.  The
> @@ -209,6 +212,9 @@ enum damos_quota_goal_metric {
>   *
>   * If @metric is DAMOS_QUOTA_NODE_MEM_{USED,FREE}_BP, @nid represents the node
>   * id of the target node to account the used/free memory.
> + *
> + * If @metric is DAMOS_QUOTA_NODE_MEMCG_USED_BP, @nid and @memcg_id represents
> + * the node id and the cgroup to account the used memory for.
>   */
>  struct damos_quota_goal {
>  	enum damos_quota_goal_metric metric;
> @@ -217,7 +223,10 @@ struct damos_quota_goal {
>  	/* metric-dependent fields */
>  	union {
>  		u64 last_psi_total;
> -		int nid;
> +		struct {
> +			int nid;
> +			unsigned short memcg_id;
> +		};
>  	};
>  	struct list_head list;
>  };
> -- 
> 2.39.5
> 


Thanks,
SJ