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From: SJ Park <sj@kernel.org>
Cc: SJ 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 3/6] mm/damon/core: s/nr_accesses_to_accesses_bp/sample_count_to_bp/
Date: Mon,  6 Jul 2026 21:38:23 -0700	[thread overview]
Message-ID: <20260707043828.97900-4-sj@kernel.org> (raw)
In-Reply-To: <20260707043828.97900-1-sj@kernel.org>

damon_nr_accesses_to_accesses_bp() actually converts a positive sample
count to the ratio.  Rename it to better describe what it really does
and not confusing for more general uses.

Also remove the obsolete comment about division-by-zero.  Commit
35d4a3cf70a8 ("mm/damon/ops-common: handle extreme intervals in
damon_hot_score()") modified damon_nr_samples_per_aggr() to always
return non-zero.  Hence no division-by-zero of the note can happen.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/core.c             | 17 +++++------------
 mm/damon/tests/core-kunit.h |  8 ++++----
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index ca530faaa4f83..718268df27fa7 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -883,25 +883,18 @@ static unsigned int damon_sample_bp_to_count(
 	return bp * damon_nr_samples_per_aggr(attrs) / 10000;
 }
 
-/*
- * Convert nr_accesses to access ratio in bp (per 10,000).
- *
- * Callers should ensure attrs.aggr_interval is not zero, like
- * damon_update_monitoring_results() does .  Otherwise, divide-by-zero would
- * happen.
- */
-static unsigned int damon_nr_accesses_to_accesses_bp(
-		unsigned int nr_accesses, struct damon_attrs *attrs)
+/* convert sample count to ratio in bp (per 10,000) */
+static unsigned int damon_sample_count_to_bp(
+		unsigned int count, struct damon_attrs *attrs)
 {
-	return mult_frac(nr_accesses, 10000, damon_nr_samples_per_aggr(attrs));
+	return mult_frac(count, 10000, damon_nr_samples_per_aggr(attrs));
 }
 
 static unsigned int damon_nr_accesses_for_new_attrs(unsigned int nr_accesses,
 		struct damon_attrs *old_attrs, struct damon_attrs *new_attrs)
 {
 	return damon_sample_bp_to_count(
-			damon_nr_accesses_to_accesses_bp(
-				nr_accesses, old_attrs),
+			damon_sample_count_to_bp(nr_accesses, old_attrs),
 			new_attrs);
 }
 
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 0124f83b39b83..86eae3a590354 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -575,7 +575,7 @@ static void damon_test_set_regions(struct kunit *test)
 			}, 3);
 }
 
-static void damon_test_nr_accesses_to_accesses_bp(struct kunit *test)
+static void damon_test_sample_count_to_bp(struct kunit *test)
 {
 	struct damon_attrs attrs = {
 		.sample_interval = 10,
@@ -585,7 +585,7 @@ static void damon_test_nr_accesses_to_accesses_bp(struct kunit *test)
 	/*
 	 * In some cases such as 32bit architectures where UINT_MAX is
 	 * ULONG_MAX, attrs.aggr_interval becomes zero.  Calling
-	 * damon_nr_accesses_to_accesses_bp() in the case will cause
+	 * damon_sample_count_to_bp() in the case will cause
 	 * divide-by-zero.  Such case is prohibited in normal execution since
 	 * the caution is documented on the comment for the function, and
 	 * damon_update_monitoring_results() does the check.  Skip the test in
@@ -594,7 +594,7 @@ static void damon_test_nr_accesses_to_accesses_bp(struct kunit *test)
 	if (!attrs.aggr_interval)
 		kunit_skip(test, "aggr_interval is zero.");
 
-	KUNIT_EXPECT_EQ(test, damon_nr_accesses_to_accesses_bp(123, &attrs), 0);
+	KUNIT_EXPECT_EQ(test, damon_sample_count_to_bp(123, &attrs), 0);
 }
 
 static void damon_test_update_monitoring_result(struct kunit *test)
@@ -1572,7 +1572,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_split_above_half_progresses),
 	KUNIT_CASE(damon_test_ops_registration),
 	KUNIT_CASE(damon_test_set_regions),
-	KUNIT_CASE(damon_test_nr_accesses_to_accesses_bp),
+	KUNIT_CASE(damon_test_sample_count_to_bp),
 	KUNIT_CASE(damon_test_update_monitoring_result),
 	KUNIT_CASE(damon_test_set_attrs),
 	KUNIT_CASE(damon_test_mvsum),
-- 
2.47.3

  parent reply	other threads:[~2026-07-07  4:39 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-07  4:38 [RFC PATCH 0/6] mm/damon: update probe hits for runtime parameter commits SJ Park
2026-07-07  4:38 ` [RFC PATCH 1/6] mm/damon/core: s/damon_max_nr_accesses()/damon_nr_samples_per_aggr()/ SJ Park
2026-07-07  4:48   ` sashiko-bot
2026-07-07  5:01     ` SJ Park
2026-07-07  4:38 ` [RFC PATCH 2/6] mm/damon/core: s/accesses_bp_to_nr_accesses/sample_bp_to_count/ SJ Park
2026-07-07  4:49   ` sashiko-bot
2026-07-07  5:02     ` SJ Park
2026-07-07  4:38 ` SJ Park [this message]
2026-07-07  4:45   ` [RFC PATCH 3/6] mm/damon/core: s/nr_accesses_to_accesses_bp/sample_count_to_bp/ sashiko-bot
2026-07-07  5:07     ` SJ Park
2026-07-07  4:38 ` [RFC PATCH 4/6] mm/damon/core: s/nr_accesses_for_new_attrs/nr_samples_for_new_attrs/ SJ Park
2026-07-07  4:50   ` sashiko-bot
2026-07-07  5:08     ` SJ Park
2026-07-07  4:38 ` [RFC PATCH 5/6] mm/damon/core: update probe hits for new parameter commit SJ Park
2026-07-07  4:51   ` sashiko-bot
2026-07-07  5:09     ` SJ Park
2026-07-07  4:38 ` [RFC PATCH 6/6] mm/damon/core: handle unreset probe_hits in probe_hits_mvsum() SJ Park

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