[RFC PATCH v3 1/7] mm/damon/core: introduce damos_quota_goal->complement

[SJ Park]

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 566960659e4a..836cf0d0de6f 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 */
+
+	/* 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 */
-- 
2.47.3