[RFC PATCH 12/13] mm/damon/core: remove damon_moving_sum() and its unit test

[SeongJae Park <sj@kernel.org>]

damon_moving_sum() is no longer being called for real purpose but its
unit test.  Testing a function that is not being used for real users
makes no sense.  Remove the test and the function.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c             | 40 -------------------------------------
 mm/damon/tests/core-kunit.h | 16 ---------------
 2 files changed, 56 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index eb129e3f7029d..1b78b2eb99e49 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -3718,46 +3718,6 @@ int damon_set_region_system_rams_default(struct damon_target *t,
 	return damon_set_regions(t, &addr_range, 1, min_region_sz);
 }
 
-/*
- * damon_moving_sum() - Calculate an inferred moving sum value.
- * @mvsum:	Inferred sum of the last @len_window values.
- * @nomvsum:	Non-moving sum of the last discrete @len_window window values.
- * @len_window:	The number of last values to take care of.
- * @new_value:	New value that will be added to the pseudo moving sum.
- *
- * Moving sum (moving average * window size) is good for handling noise, but
- * the cost of keeping past values can be high for arbitrary window size.  This
- * function implements a lightweight pseudo moving sum function that doesn't
- * keep the past window values.
- *
- * It simply assumes there was no noise in the past, and get the no-noise
- * assumed past value to drop from @nomvsum and @len_window.  @nomvsum is a
- * non-moving sum of the last window.  For example, if @len_window is 10 and we
- * have 25 values, @nomvsum is the sum of the 11th to 20th values of the 25
- * values.  Hence, this function simply drops @nomvsum / @len_window from
- * given @mvsum and add @new_value.
- *
- * For example, if @len_window is 10 and @nomvsum is 50, the last 10 values for
- * the last window could be vary, e.g., 0, 10, 0, 10, 0, 10, 0, 0, 0, 20.  For
- * calculating next moving sum with a new value, we should drop 0 from 50 and
- * add the new value.  However, this function assumes it got value 5 for each
- * of the last ten times.  Based on the assumption, when the next value is
- * measured, it drops the assumed past value, 5 from the current sum, and add
- * the new value to get the updated pseduo-moving average.
- *
- * This means the value could have errors, but the errors will be disappeared
- * for every @len_window aligned calls.  For example, if @len_window is 10, the
- * pseudo moving sum with 11th value to 19th value would have an error.  But
- * the sum with 20th value will not have the error.
- *
- * Return: Pseudo-moving average after getting the @new_value.
- */
-static unsigned int damon_moving_sum(unsigned int mvsum, unsigned int nomvsum,
-		unsigned int len_window, unsigned int new_value)
-{
-	return mvsum - nomvsum / len_window + new_value;
-}
-
 /**
  * damon_update_region_access_rate() - Update the access rate of a region.
  * @r:		The DAMON region to update for its access check result.
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index d1f019ab6fc25..df16cc070eeb0 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -600,21 +600,6 @@ static void damon_test_set_attrs(struct kunit *test)
 	damon_destroy_ctx(c);
 }
 
-static void damon_test_moving_sum(struct kunit *test)
-{
-	unsigned int mvsum = 50000, nomvsum = 50000, len_window = 10;
-	unsigned int new_values[] = {10000, 0, 10000, 0, 0, 0, 10000, 0, 0, 0};
-	unsigned int expects[] = {55000, 50000, 55000, 50000, 45000, 40000,
-		45000, 40000, 35000, 30000};
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(new_values); i++) {
-		mvsum = damon_moving_sum(mvsum, nomvsum, len_window,
-				new_values[i]);
-		KUNIT_EXPECT_EQ(test, mvsum, expects[i]);
-	}
-}
-
 static void damon_test_mvsum(struct kunit *test)
 {
 	unsigned long input_expects[] = {
@@ -1516,7 +1501,6 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_nr_accesses_to_accesses_bp),
 	KUNIT_CASE(damon_test_update_monitoring_result),
 	KUNIT_CASE(damon_test_set_attrs),
-	KUNIT_CASE(damon_test_moving_sum),
 	KUNIT_CASE(damon_test_mvsum),
 	KUNIT_CASE(damos_test_new_filter),
 	KUNIT_CASE(damos_test_commit_quota_goal),
-- 
2.47.3