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From: SeongJae Park <sj@kernel.org>
Cc: SeongJae Park <sj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	damon@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [RFC PATCH v1.1 11/13] mm/damon/core: remove nr_accesses_bp setups and updates
Date: Sat, 20 Jun 2026 10:22:41 -0700	[thread overview]
Message-ID: <20260620172244.90953-12-sj@kernel.org> (raw)
In-Reply-To: <20260620172244.90953-1-sj@kernel.org>

DAMON core sets and updates nr_accesses_bp in multiple places.  It
explains how delicate it is.  The field is no more being used for any
real purpose, and replaced by a simpler function.  Remove the setups and
updates.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 6db157ee25129..471b58e8e31b9 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -296,7 +296,6 @@ struct damon_region *damon_new_region(unsigned long start, unsigned long end)
 	region->ar.start = start;
 	region->ar.end = end;
 	region->nr_accesses = 0;
-	region->nr_accesses_bp = 0;
 	for (i = 0; i < DAMON_MAX_PROBES; i++)
 		region->probe_hits[i] = 0;
 	INIT_LIST_HEAD(&region->list);
@@ -871,7 +870,6 @@ static void damon_update_monitoring_result(struct damon_region *r,
 	if (!aggregating) {
 		r->nr_accesses = damon_nr_accesses_for_new_attrs(
 				r->nr_accesses, old_attrs, new_attrs);
-		r->nr_accesses_bp = r->nr_accesses * 10000;
 	} else {
 		/*
 		 * if this is called in the middle of the aggregation, reset
@@ -881,7 +879,6 @@ static void damon_update_monitoring_result(struct damon_region *r,
 		 */
 		r->last_nr_accesses = damon_nr_accesses_for_new_attrs(
 				r->last_nr_accesses, old_attrs, new_attrs);
-		r->nr_accesses_bp = r->last_nr_accesses * 10000;
 		r->nr_accesses = 0;
 	}
 	r->age = damon_age_for_new_attrs(r->age, old_attrs, new_attrs);
@@ -3098,7 +3095,6 @@ static void damon_merge_two_regions(struct damon_target *t,
 
 	l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) /
 			(sz_l + sz_r);
-	l->nr_accesses_bp = l->nr_accesses * 10000;
 	l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r);
 	l->ar.end = r->ar.end;
 	/* todo: do this for only installed probes */
@@ -3210,7 +3206,6 @@ static void damon_split_region_at(struct damon_target *t,
 
 	new->age = r->age;
 	new->last_nr_accesses = r->last_nr_accesses;
-	new->nr_accesses_bp = r->nr_accesses_bp;
 	new->nr_accesses = r->nr_accesses;
 	/* todo: do this for only installed probes */
 	memcpy(new->probe_hits, r->probe_hits, sizeof(r->probe_hits));
@@ -3779,18 +3774,6 @@ static unsigned int damon_moving_sum(unsigned int mvsum, unsigned int nomvsum,
 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 = damon_max_nr_accesses(attrs);
-	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++;
 }
-- 
2.47.3

  parent reply	other threads:[~2026-06-20 17:23 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-20 17:22 [RFC PATCH v1.1 00/13] mm/damon: optimize out nr_accesses_bp SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 01/13] mm/damon: introduce damon_nr_accesses_mvsum() SeongJae Park
2026-06-20 17:36   ` sashiko-bot
2026-06-20 17:39     ` SeongJae Park
2026-06-20 17:41       ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 02/13] mm/damon/tests/core-kunit: test damon_mvsum() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 03/13] mm/damon/core: use damon_nr_accesses_mvsum() in __damos_valid_target() SeongJae Park
2026-06-20 17:41   ` sashiko-bot
2026-06-20 18:07     ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 04/13] mm/damon/core: use damon_nr_accesses_mvsum() for damos region tracing SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 05/13] mm/damon/sysfs-schemes: use damon_nr_accesses_mvsum() for damo regions SeongJae Park
2026-06-20 17:37   ` sashiko-bot
2026-06-20 18:19     ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 06/13] mm/damon/core: remove damon_warn_fix_nr_accesses_corruption() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 07/13] mm/damon/core: remove damon_verify_reset_aggregated() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 08/13] mm/damon/core: remove damon_verify_merge_regions_of() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 09/13] mm/damon/tests/core-kunit: remove nr_accesses_bp setup and tests SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 10/13] selftests/damon/drgn_dump_damon_status: do not dump nr_accesses_bp SeongJae Park
2026-06-20 17:22 ` SeongJae Park [this message]
2026-06-20 17:34   ` [RFC PATCH v1.1 11/13] mm/damon/core: remove nr_accesses_bp setups and updates sashiko-bot
2026-06-20 17:45     ` SeongJae Park
2026-06-20 18:20       ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 12/13] mm/damon/core: remove damon_moving_sum() and its unit test SeongJae Park
2026-06-20 17:35   ` sashiko-bot
2026-06-20 17:47     ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 13/13] mm/damon: remove damon_region->nr_accesses_bp SeongJae Park

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