[6/8] mm/damon/core: use pseudo-moving sum for nr_accesses_bp

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 15f24b23c9a0..0fe13482df63 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -40,7 +40,8 @@  struct damon_addr_range {
  * @ar:			The address range of the region.
  * @sampling_addr:	Address of the sample for the next access check.
  * @nr_accesses:	Access frequency of this region.
- * @nr_accesses_bp:	@nr_accesses in basis point (0.01%).
+ * @nr_accesses_bp:	@nr_accesses in basis point (0.01%) that updated for
+ *			each sampling interval.
  * @list:		List head for siblings.
  * @age:		Age of this region.
  *
@@ -51,7 +52,11 @@  struct damon_addr_range {
  * damon_update_region_access_rate().
  *
  * @nr_accesses_bp is another representation of @nr_accesses in basis point
- * (1 in 10,000) that updated every aggregation interval.
+ * (1 in 10,000) that updated for every &damon_attrs->sample_interval in a
+ * manner similar to moving sum.  By the algorithm, this value becomes
+ * @nr_accesses * 10000 for every &struct damon_attrs->aggr_interval.  This can
+ * be used when the aggregation interval is too huge and therefore cannot wait
+ * for it before getting the access monitoring results.
  *
  * @age is initially zero, increased for each aggregation interval, and reset
  * to zero again if the access frequency is significantly changed.  If two
@@ -629,7 +634,8 @@  int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 		unsigned int nr_ranges);
 unsigned int damon_moving_sum(unsigned int mvsum, unsigned int nomvsum,
 		unsigned int len_window, unsigned int new_value);
-void damon_update_region_access_rate(struct damon_region *r, bool accessed);
+void damon_update_region_access_rate(struct damon_region *r, bool accessed,
+		struct damon_attrs *attrs);
 
 struct damos_filter *damos_new_filter(enum damos_filter_type type,
 		bool matching);
diff --git a/mm/damon/core.c b/mm/damon/core.c
index ce85c00b0a4c..29ee1fc18393 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1599,14 +1599,28 @@  unsigned int damon_moving_sum(unsigned int mvsum, unsigned int nomvsum,
  * damon_update_region_access_rate() - Update the access rate of a region.
  * @r:		The DAMON region to update for its access check result.
  * @accessed:	Whether the region has accessed during last sampling interval.
+ * @attrs:	The damon_attrs of the DAMON context.
  *
  * Update the access rate of a region with the region's last sampling interval
  * access check result.
  *
  * Usually this will be called by &damon_operations->check_accesses callback.
  */
-void damon_update_region_access_rate(struct damon_region *r, bool accessed)
+void damon_update_region_access_rate(struct damon_region *r, bool accessed,
+		struct damon_attrs *attrs)
 {
+	unsigned int len_window = 1;
+
+	/*
+	 * sample_interval can be zero, but cannot be larger than
+	 * aggr_interval, owing to validation of damon_set_attrs().
+	 */
+	if (attrs->sample_interval)
+		len_window = attrs->aggr_interval / attrs->sample_interval;
+	r->nr_accesses_bp = damon_moving_sum(r->nr_accesses_bp,
+			r->last_nr_accesses * 10000, len_window,
+			accessed ? 10000 : 0);
+
 	if (accessed)
 		r->nr_accesses++;
 }
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 44f21860b555..081e2a325778 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -148,7 +148,8 @@  static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
 	return accessed;
 }
 
-static void __damon_pa_check_access(struct damon_region *r)
+static void __damon_pa_check_access(struct damon_region *r,
+		struct damon_attrs *attrs)
 {
 	static unsigned long last_addr;
 	static unsigned long last_folio_sz = PAGE_SIZE;
@@ -157,12 +158,12 @@  static void __damon_pa_check_access(struct damon_region *r)
 	/* If the region is in the last checked page, reuse the result */
 	if (ALIGN_DOWN(last_addr, last_folio_sz) ==
 				ALIGN_DOWN(r->sampling_addr, last_folio_sz)) {
-		damon_update_region_access_rate(r, last_accessed);
+		damon_update_region_access_rate(r, last_accessed, attrs);
 		return;
 	}
 
 	last_accessed = damon_pa_young(r->sampling_addr, &last_folio_sz);
-	damon_update_region_access_rate(r, last_accessed);
+	damon_update_region_access_rate(r, last_accessed, attrs);
 
 	last_addr = r->sampling_addr;
 }
@@ -175,7 +176,7 @@  static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
 
 	damon_for_each_target(t, ctx) {
 		damon_for_each_region(r, t) {
-			__damon_pa_check_access(r);
+			__damon_pa_check_access(r, &ctx->attrs);
 			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
 		}
 	}
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index e36303271f9d..af2cb82e1fad 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -557,26 +557,27 @@  static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
  * r	the region to be checked
  */
 static void __damon_va_check_access(struct mm_struct *mm,
-				struct damon_region *r, bool same_target)
+				struct damon_region *r, bool same_target,
+				struct damon_attrs *attrs)
 {
 	static unsigned long last_addr;
 	static unsigned long last_folio_sz = PAGE_SIZE;
 	static bool last_accessed;
 
 	if (!mm) {
-		damon_update_region_access_rate(r, false);
+		damon_update_region_access_rate(r, false, attrs);
 		return;
 	}
 
 	/* If the region is in the last checked page, reuse the result */
 	if (same_target && (ALIGN_DOWN(last_addr, last_folio_sz) ==
 				ALIGN_DOWN(r->sampling_addr, last_folio_sz))) {
-		damon_update_region_access_rate(r, last_accessed);
+		damon_update_region_access_rate(r, last_accessed, attrs);
 		return;
 	}
 
 	last_accessed = damon_va_young(mm, r->sampling_addr, &last_folio_sz);
-	damon_update_region_access_rate(r, last_accessed);
+	damon_update_region_access_rate(r, last_accessed, attrs);
 
 	last_addr = r->sampling_addr;
 }
@@ -593,7 +594,8 @@  static unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
 		mm = damon_get_mm(t);
 		same_target = false;
 		damon_for_each_region(r, t) {
-			__damon_va_check_access(mm, r, same_target);
+			__damon_va_check_access(mm, r, same_target,
+					&ctx->attrs);
 			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
 			same_target = true;
 		}