1 files changed, 51 insertions, 1 deletions

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 1217566a0ebc..c93325efddd7 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -147,6 +147,45 @@ struct damos_quota {
 };
 
 /**
+ * enum damos_wmark_metric - Represents the watermark metric.
+ *
+ * @DAMOS_WMARK_NONE:		Ignore the watermarks of the given scheme.
+ * @DAMOS_WMARK_FREE_MEM_RATE:	Free memory rate of the system in [0,1000].
+ */
+enum damos_wmark_metric {
+	DAMOS_WMARK_NONE,
+	DAMOS_WMARK_FREE_MEM_RATE,
+};
+
+/**
+ * struct damos_watermarks - Controls when a given scheme should be activated.
+ * @metric:	Metric for the watermarks.
+ * @interval:	Watermarks check time interval in microseconds.
+ * @high:	High watermark.
+ * @mid:	Middle watermark.
+ * @low:	Low watermark.
+ *
+ * If &metric is &DAMOS_WMARK_NONE, the scheme is always active.  Being active
+ * means DAMON does monitoring and applying the action of the scheme to
+ * appropriate memory regions.  Else, DAMON checks &metric of the system for at
+ * least every &interval microseconds and works as below.
+ *
+ * If &metric is higher than &high, the scheme is inactivated.  If &metric is
+ * between &mid and &low, the scheme is activated.  If &metric is lower than
+ * &low, the scheme is inactivated.
+ */
+struct damos_watermarks {
+	enum damos_wmark_metric metric;
+	unsigned long interval;
+	unsigned long high;
+	unsigned long mid;
+	unsigned long low;
+
+/* private: */
+	bool activated;
+};
+
+/**
  * struct damos - Represents a Data Access Monitoring-based Operation Scheme.
  * @min_sz_region:	Minimum size of target regions.
  * @max_sz_region:	Maximum size of target regions.
@@ -156,6 +195,7 @@ struct damos_quota {
  * @max_age_region:	Maximum age of target regions.
  * @action:		&damo_action to be applied to the target regions.
  * @quota:		Control the aggressiveness of this scheme.
+ * @wmarks:		Watermarks for automated (in)activation of this scheme.
  * @stat_count:		Total number of regions that this scheme is applied.
  * @stat_sz:		Total size of regions that this scheme is applied.
  * @list:		List head for siblings.
@@ -166,6 +206,14 @@ struct damos_quota {
  * those.  To avoid consuming too much CPU time or IO resources for the
  * &action, &quota is used.
  *
+ * To do the work only when needed, schemes can be activated for specific
+ * system situations using &wmarks.  If all schemes that registered to the
+ * monitoring context are inactive, DAMON stops monitoring either, and just
+ * repeatedly checks the watermarks.
+ *
+ * If all schemes that registered to a &struct damon_ctx are inactive, DAMON
+ * stops monitoring and just repeatedly checks the watermarks.
+ *
  * After applying the &action to each region, &stat_count and &stat_sz is
  * updated to reflect the number of regions and total size of regions that the
  * &action is applied.
@@ -179,6 +227,7 @@ struct damos {
 	unsigned int max_age_region;
 	enum damos_action action;
 	struct damos_quota quota;
+	struct damos_watermarks wmarks;
 	unsigned long stat_count;
 	unsigned long stat_sz;
 	struct list_head list;
@@ -384,7 +433,8 @@ struct damos *damon_new_scheme(
 		unsigned long min_sz_region, unsigned long max_sz_region,
 		unsigned int min_nr_accesses, unsigned int max_nr_accesses,
 		unsigned int min_age_region, unsigned int max_age_region,
-		enum damos_action action, struct damos_quota *quota);
+		enum damos_action action, struct damos_quota *quota,
+		struct damos_watermarks *wmarks);
 void damon_add_scheme(struct damon_ctx *ctx, struct damos *s);
 void damon_destroy_scheme(struct damos *s);