ext4: add test_mb_mark_used_cost to estimate cost of mb_mark_used

Add test_mb_mark_used_cost to estimate cost of mb_mark_used
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Link: https://lore.kernel.org/r/20240424061904.987525-3-shikemeng@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/mballoc-test.c

@@ -883,6 +883,56 @@ static void test_mb_free_blocks(struct kunit *test)
 	ext4_mb_unload_buddy(&e4b);
 }
 
+#define COUNT_FOR_ESTIMATE 100000
+static void test_mb_mark_used_cost(struct kunit *test)
+{
+	struct ext4_buddy e4b;
+	struct super_block *sb = (struct super_block *)test->priv;
+	struct ext4_free_extent ex;
+	int ret;
+	struct test_range ranges[TEST_RANGE_COUNT];
+	int i, j;
+	unsigned long start, end, all = 0;
+
+	/* buddy cache assumes that each page contains at least one block */
+	if (sb->s_blocksize > PAGE_SIZE)
+		kunit_skip(test, "blocksize exceeds pagesize");
+
+	ret = ext4_mb_load_buddy(sb, TEST_GOAL_GROUP, &e4b);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ex.fe_group = TEST_GOAL_GROUP;
+	for (j = 0; j < COUNT_FOR_ESTIMATE; j++) {
+		mbt_generate_test_ranges(sb, ranges, TEST_RANGE_COUNT);
+		start = jiffies;
+		for (i = 0; i < TEST_RANGE_COUNT; i++) {
+			if (ranges[i].len == 0)
+				continue;
+
+			ex.fe_start = ranges[i].start;
+			ex.fe_len = ranges[i].len;
+			ext4_lock_group(sb, TEST_GOAL_GROUP);
+			mb_mark_used(&e4b, &ex);
+			ext4_unlock_group(sb, TEST_GOAL_GROUP);
+		}
+		end = jiffies;
+		all += (end - start);
+
+		for (i = 0; i < TEST_RANGE_COUNT; i++) {
+			if (ranges[i].len == 0)
+				continue;
+
+			ext4_lock_group(sb, TEST_GOAL_GROUP);
+			mb_free_blocks(NULL, &e4b, ranges[i].start,
+				       ranges[i].len);
+			ext4_unlock_group(sb, TEST_GOAL_GROUP);
+		}
+	}
+
+	kunit_info(test, "costed jiffies %lu\n", all);
+	ext4_mb_unload_buddy(&e4b);
+}
+
 static const struct mbt_ext4_block_layout mbt_test_layouts[] = {
 	{
 		.blocksize_bits = 10,
@@ -925,6 +975,8 @@ static struct kunit_case mbt_test_cases[] = {
 	KUNIT_CASE_PARAM(test_mb_mark_used, mbt_layouts_gen_params),
 	KUNIT_CASE_PARAM(test_mb_free_blocks, mbt_layouts_gen_params),
 	KUNIT_CASE_PARAM(test_mark_diskspace_used, mbt_layouts_gen_params),
+	KUNIT_CASE_PARAM_ATTR(test_mb_mark_used_cost, mbt_layouts_gen_params,
+			      { .speed = KUNIT_SPEED_SLOW }),
 	{}
 };