mm/damon/core: use pseudo-moving sum for nr_accesses_bp

Let nr_accesses_bp be calculated as a pseudo-moving sum that updated for
every sampling interval, using damon_moving_sum().  This is assumed to be
useful for cases that the aggregation interval is set quite huge, but the
monivoting results need to be collected earlier than next aggregation
interval is passed.

Link: https://lkml.kernel.org/r/20230915025251.72816-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 27 insertions, 10 deletions

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 @@ out:
 	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 02ab448d9b1e..a4d1f63c5b23 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -558,26 +558,27 @@ 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;
 }
@@ -594,7 +595,8 @@ 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;
 		}