On 2017/11/7 19:14, Fan Li wrote:
> 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...@samsung.com>
Reviewed-by: Chao Yu <yuch...@huawei.com>
Thanks,
> ---
> fs/f2fs/node.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index fef5c68..d234c6e 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -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 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi)
> 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));
>
