Re: [PATCH 1/8] mm/damon/core: introduce damos_quota_goal->complement

[Gutierrez Asier]

Hi SJ,

On 9/29/2026 11:01 AM, SJ Park wrote:
> Introduce damos_quota_goal->complement for specifying whether to use a
> complemented value of the given goal target metric.  Add the field to
> the data structure and implement essential core support.  Handle the
> flag in the quota goal commit and current quota goal metric value
> retrieval.
> 
> Signed-off-by: SJ Park <sj@xxxxxxxxxx>
> ---
>  include/linux/damon.h |  2 ++
>  mm/damon/core.c       | 26 +++++++++++++++++++++++++-
>  2 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/damon.h b/include/linux/damon.h
> index 6a29dc2ac8db..42234839ce29 100644
> --- a/include/linux/damon.h
> +++ b/include/linux/damon.h
> @@ -169,6 +169,7 @@ enum damos_quota_goal_metric {
>  /**
>   * struct damos_quota_goal - DAMOS scheme quota auto-tuning goal.
>   * @metric:		Metric to be used for representing the goal.
> + * @complement:		Use the complement of the metric.
>   * @target_value:	Target value of @metric to achieve with the tuning.
>   * @current_value:	Current value of @metric.
>   * @nid:		Node id.
> @@ -191,6 +192,7 @@ enum damos_quota_goal_metric {
>   */
>  struct damos_quota_goal {
>  	enum damos_quota_goal_metric metric;
> +	bool complement;
>  	unsigned long target_value;
>  	unsigned long current_value;
>  	/* metric-dependent fields */
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 5ecbea5d71e1..1ab5154511e6 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -1224,6 +1224,7 @@ static int damos_commit_quota_goal(
>  	if (!src->target_value)
>  		return  -EINVAL;
>  	dst->metric = src->metric;
> +	dst->complement = src->complement;
>  	dst->target_value = src->target_value;
>  	if (dst->metric == DAMOS_QUOTA_USER_INPUT)
>  		dst->current_value = src->current_value;
> @@ -2960,10 +2961,18 @@ static void damos_set_psi_current_val(u64 now_psi_total,
>  		struct damos_quota_goal *goal, struct damos *s)
>  {
>  	u64 last_psi_total = goal->last_psi_total;
> +	unsigned long val;
>  
>  	goal->last_psi_total = now_psi_total;
>  	if (last_psi_total != U64_MAX) {
> -		goal->current_value = now_psi_total - last_psi_total;
> +		val = now_psi_total - last_psi_total;
> +		if (goal->complement) {
> +			if (val < s->quota.reset_interval * 1000)
> +				val = s->quota.reset_interval * 1000 - val;
> +			else
> +				val = 0;
> +		}
> +		goal->current_value = val;
>  		return;
>  	}
>  	/* uninitialized last_psi_total; make no effect this round */
> @@ -3255,6 +3264,21 @@ static void damos_set_quota_goal_current_value(struct damon_ctx *c,
>  	default:
>  		break;
>  	}
> +	if (!goal->complement)
> +		return;
> +
> +	/* updte current_value to complemented value */
There is a typo there. It should be "update". Also, what is the 
purpose of this comment? It doesn't explain anything, which may
not be obvious.> +
> +	/* for user_input, users set complemented value on their own */
> +	if (goal->metric == DAMOS_QUOTA_USER_INPUT)
> +		return;
> +	/* damos_set_psi_current_val() handles complement flag itself */
> +	if (goal->metric == DAMOS_QUOTA_SOME_MEM_PSI_US)
> +		return;
> +	if (goal->current_value < 10000)
> +		goal->current_value = 10000 - goal->current_value;
> +	else
> +		goal->current_value = 0;
>  }
>  
>  /* Return the highest score since it makes schemes least aggressive */

-- 
Asier Gutierrez
Huawei