RE: [f2fs-dev] [PATCH V2 RESEND] f2fs: check all ones or zeros bitmap with bitops for better mount performance

[Changman Lee <cm224.lee@samsung.com>]

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Review attached patch, please.

-----Original Message-----
From: Chao Yu [mailto:chao2.yu@samsung.com] 
Sent: Tuesday, October 29, 2013 3:51 PM
To: jaegeuk.kim@samsung.com
Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
linux-f2fs-devel@lists.sourceforge.net
Subject: [f2fs-dev] [PATCH V2 RESEND] f2fs: check all ones or zeros bitmap
with bitops for better mount performance

Previously, check_block_count check valid_map with bit data type in common
scenario that sit has all ones or zeros bitmap, it makes low mount
performance.
So let's check the special bitmap with integer data type instead of the bit
one.

v1-->v2:
    use find_next_{zero_}bit_le for better performance and readable as
Jaegeuk suggested.
	use neat logogram in comment as Gu Zheng suggested.
	search continuous ones or zeros for better performance when checking
mixed bitmap.

Suggested-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Signed-off-by: Shu Tan <shu.tan@samsung.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
 fs/f2fs/segment.h |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index abe7094..a7abfa8
100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -550,8 +550,9 @@ static inline void check_block_count(struct f2fs_sb_info
*sbi,  {
 	struct f2fs_sm_info *sm_info = SM_I(sbi);
 	unsigned int end_segno = sm_info->segment_count - 1;
+	bool is_valid  = test_bit_le(0, raw_sit->valid_map) ? true : false;
 	int valid_blocks = 0;
-	int i;
+	int cur_pos = 0, next_pos;
 
 	/* check segment usage */
 	BUG_ON(GET_SIT_VBLOCKS(raw_sit) > sbi->blocks_per_seg); @@ -560,9
+561,19 @@ static inline void check_block_count(struct f2fs_sb_info *sbi,
 	BUG_ON(segno > end_segno);
 
 	/* check bitmap with valid block count */
-	for (i = 0; i < sbi->blocks_per_seg; i++)
-		if (f2fs_test_bit(i, raw_sit->valid_map))
-			valid_blocks++;
+	do {
+		if (is_valid) {
+			next_pos =
find_next_zero_bit_le(&raw_sit->valid_map,
+					sbi->blocks_per_seg,
+					cur_pos);
+			valid_blocks += next_pos - cur_pos;
+		} else
+			next_pos = find_next_bit_le(&raw_sit->valid_map,
+					sbi->blocks_per_seg,
+					cur_pos);
+		cur_pos = next_pos;
+		is_valid = !is_valid;
+	} while (cur_pos < sbi->blocks_per_seg);
 	BUG_ON(GET_SIT_VBLOCKS(raw_sit) != valid_blocks);  }
 
--
1.7.9.5


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>From 05ca99b07e28e1fe970e0ed547b51f93a9c0b94c Mon Sep 17 00:00:00 2001
From: Changman Lee <cm224.lee@samsung.com>
Date: Tue, 29 Oct 2013 16:34:43 +0900
Subject: [PATCH] f2fs: use pre-calculated value to get sum of valid blocks

Using pre-calculated value is more fast than looking into bitmap on
runnnig time.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
---
 fs/f2fs/f2fs.h    |    1 +
 fs/f2fs/hash.c    |   24 ++++++++++++++++++++++++
 fs/f2fs/segment.h |    4 ++--
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index a61cc5f..288be6a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -71,6 +71,7 @@ static inline bool f2fs_crc_valid(__u32 blk_crc, void *buf, size_t buf_size)
 	return f2fs_crc32(buf, buf_size) == blk_crc;
 }
 
+extern int bit_count_byte(unsigned char);
 /*
  * For checkpoint manager
  */
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
index 6eb8d26..2dd9b5a 100644
--- a/fs/f2fs/hash.c
+++ b/fs/f2fs/hash.c
@@ -99,3 +99,27 @@ f2fs_hash_t f2fs_dentry_hash(const char *name, size_t len)
 	f2fs_hash = cpu_to_le32(hash & ~F2FS_HASH_COL_BIT);
 	return f2fs_hash;
 }
+
+static const int bits_in_byte[256] = {
+	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
+};
+
+int bit_count_byte(unsigned char n)
+{
+	return bits_in_byte[n];
+}
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index abe7094..d5aa4cc 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -561,8 +561,8 @@ static inline void check_block_count(struct f2fs_sb_info *sbi,
 
 	/* check bitmap with valid block count */
 	for (i = 0; i < sbi->blocks_per_seg; i++)
-		if (f2fs_test_bit(i, raw_sit->valid_map))
-			valid_blocks++;
+		valid_blocks += bit_count_byte(raw_sit->valid_map[i]);
+
 	BUG_ON(GET_SIT_VBLOCKS(raw_sit) != valid_blocks);
 }
 
-- 
1.7.10.4