On 10/28/2013 10:19 AM, 이창만 wrote: > 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. According to my understanding, memcmp: one by one search, find_next_bit: binary search. Regards, Gu > > > -----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.clktrk > _______________________________________________ > 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-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- 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
