f2fs: optimize the way of traversing free_nid_bitmap (97456574) · Commits · 戴 / test

We call scan_free_nid_bits only when there isn't many free nids left, it means that marked bits in free_nid_bitmap are supposed to be few, use find_next_bit_le is more efficient in such case. According to my tests, use find_next_bit_le instead of test_bit_le will cut down the traversal time to one third of its original. Signed-off-by:

Fan li <fanofcode.li@samsung.com> Reviewed-by:

Chao Yu <yuchao0@huawei.com> Signed-off-by:

Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/node.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -1955,6 +1955,7 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi)
		struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
		struct f2fs_journal *journal = curseg->journal;
		unsigned int i, idx;
		nid_t nid;

		down_read(&nm_i->nat_tree_lock);

		@@ -1964,10 +1965,10 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi)
		if (!nm_i->free_nid_count[i])
		continue;
		for (idx = 0; idx < NAT_ENTRY_PER_BLOCK; idx++) {
		nid_t nid;

		if (!test_bit_le(idx, nm_i->free_nid_bitmap[i]))
		continue;
		idx = find_next_bit_le(nm_i->free_nid_bitmap[i],
		NAT_ENTRY_PER_BLOCK, idx);
		if (idx >= NAT_ENTRY_PER_BLOCK)
		break;

		nid = i * NAT_ENTRY_PER_BLOCK + idx;
		add_free_nid(sbi, nid, true);
		@@ -1980,7 +1981,6 @@ out:
		down_read(&curseg->journal_rwsem);
		for (i = 0; i < nats_in_cursum(journal); i++) {
		block_t addr;
		nid_t nid;

		addr = le32_to_cpu(nat_in_journal(journal, i).block_addr);
		nid = le32_to_cpu(nid_in_journal(journal, i));

Admin message