Hi Lee, > -----Original Message----- > From: 이창만 [mailto:cm224.lee@xxxxxxxxxxx] > Sent: Monday, October 28, 2013 10:20 AM > To: 'Chao Yu'; jaegeuk.kim@xxxxxxxxxxx > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; '谭姝'; linux-kernel@xxxxxxxxxxxxxxx; > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: RE: [f2fs-dev] [PATCH V2] f2fs: check all ones or zeros bitmap with > bitops for better mount performance > > To check whether bitmap are all zeros or all ones, I think memcmp is more > neat. > But I don't know exactly performance gap between memcmp and > find_next_bit. With the result of my test, find_next_bit takes less time than memcmp. If we could use {test, set, clear}_bit_le intead of f2fs_{test, set, clear}_bit, the following patch could be used for better performance. This one is better than the V2 patch for performance with mixed bitmap in my test. diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 7f94d78..32153eb --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -544,7 +544,8 @@ 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; int valid_blocks = 0; - int i; + int i, cur_pos = 0, next_pos; + bool is_valid; /* check segment usage */ BUG_ON(GET_SIT_VBLOCKS(raw_sit) > sbi->blocks_per_seg); @@ -553,9 +554,21 @@ 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++; + cur_pos = 0; + is_valid = test_bit_le(0, raw_sit->valid_map) ? true : false; + 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); } > > > -----Original Message----- > From: Chao Yu [mailto:chao2.yu@xxxxxxxxxxx] > Sent: Thursday, October 24, 2013 5:21 PM > To: jaegeuk.kim@xxxxxxxxxxx > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; '谭姝'; linux-kernel@xxxxxxxxxxxxxxx; > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: [f2fs-dev] [PATCH V2] 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. > > v2: > use find_next_bit_le/find_next_zero_bit_le for better performance and > readable as Jaegeuk suggested. > > Suggested-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx> > Signed-off-by: Tan Shu <shu.tan@xxxxxxxxxxx> > Signed-off-by: Yu Chao <chao2.yu@xxxxxxxxxxx> > --- > fs/f2fs/segment.h | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 7f94d78..d25b6af > 100644 > --- a/fs/f2fs/segment.h > +++ b/fs/f2fs/segment.h > @@ -552,6 +552,23 @@ static inline void check_block_count(struct > f2fs_sb_info *sbi, > /* check boundary of a given segment number */ > BUG_ON(segno > end_segno); > > + /* check all ones or zeros valid_map */ > + if (GET_SIT_VBLOCKS(raw_sit) == 0) { > + int pos = find_next_bit_le(&raw_sit->valid_map, > + sbi->blocks_per_seg, > + 0); > + if (pos != sbi->blocks_per_seg) > + BUG(); > + return; > + } else if (GET_SIT_VBLOCKS(raw_sit) == sbi->blocks_per_seg) { > + int pos = find_next_zero_bit_le(&raw_sit->valid_map, > + sbi->blocks_per_seg, > + 0); > + if (pos != sbi->blocks_per_seg) > + BUG(); > + return; > + } > + > /* check bitmap with valid block count */ > for (i = 0; i < sbi->blocks_per_seg; i++) > if (f2fs_test_bit(i, raw_sit->valid_map)) > -- > 1.7.9.5 > > > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60135991&iu=/4140/ostg.clktr > k > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
