[PATCH 2/5] ext4: add test_mb_mark_used_cost to estimate cost of mb_mark_used

[Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>]

Add test_mb_mark_used_cost to estimate runtime of mb_mark_used.

Result of unit test is as following:
$ ./tools/testing/kunit/kunit.py run --kunitconfig=fs/ext4/.kunitconfig --raw_output
...
        # Subtest: test_mb_mark_used_cost
    # test_mb_mark_used_cost: costed jiffies 311
        ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
    # test_mb_mark_used_cost: costed jiffies 304
        ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
        ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
 # SKIP blocksize exceeds pagesize
    # test_mb_mark_used_cost.speed: slow
    # test_mb_mark_used_cost: pass:2 fail:0 skip:1 total:3
    ok 7 test_mb_mark_used_cost
...

Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
---
 fs/ext4/mballoc-test.c | 56 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/fs/ext4/mballoc-test.c b/fs/ext4/mballoc-test.c
index 044ca5238f41..cb1a551f9596 100644
--- a/fs/ext4/mballoc-test.c
+++ b/fs/ext4/mballoc-test.c
@@ -859,6 +859,56 @@ static void test_mb_free_blocks(struct kunit *test)
 	ext4_mb_unload_buddy(&e4b);
 }
 
+#define COUNT_FOR_ESTIMATE 1000000
+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,
@@ -894,6 +944,10 @@ static void mbt_show_layout(const struct mbt_ext4_block_layout *layout,
 }
 KUNIT_ARRAY_PARAM(mbt_layouts, mbt_test_layouts, mbt_show_layout);
 
+static const struct kunit_attributes slow_attr = {
+	.speed = KUNIT_SPEED_SLOW,
+};
+
 static struct kunit_case mbt_test_cases[] = {
 	KUNIT_CASE_PARAM(test_new_blocks_simple, mbt_layouts_gen_params),
 	KUNIT_CASE_PARAM(test_free_blocks_simple, mbt_layouts_gen_params),
@@ -901,6 +955,8 @@ 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,
+			      slow_attr),
 	{}
 };
 
-- 
2.30.0