From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gu Zheng Subject: Re: [f2fs-dev] [PATCH V2] f2fs: check all ones or zeros bitmap with bitops for better mount performance Date: Thu, 24 Oct 2013 18:03:33 +0800 Message-ID: <5268F075.3000206@cn.fujitsu.com> References: <000401ced092$28087a90$78196fb0$@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: jaegeuk.kim@samsung.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, =?UTF-8?B?J+iwreWnnSc=?= To: Chao Yu Return-path: In-Reply-To: <000401ced092$28087a90$78196fb0$@samsung.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi Yu, On 10/24/2013 04:21 PM, Chao Yu wrote: > 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. If so, how about using find_first_{zero_}bit_le instead? It's more neat. Regards, Gu > > Suggested-by: Jaegeuk Kim > Signed-off-by: Tan Shu > Signed-off-by: Yu Chao > --- > 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))