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SubjectRE: [f2fs-dev] [PATCH V2 RESEND] f2fs: check all ones or zeros bitmap with bitops for better mount performance
Date

As you know, if any data or function are used once, we can use some keywords
like __initdata for data and __init for function.


-----Original Message-----
From: Chao Yu [mailto:chao2.yu@samsung.com]
Sent: Tuesday, October 29, 2013 7:52 PM
To: 'Changman Lee'; jaegeuk.kim@samsung.com
Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
linux-f2fs-devel@lists.sourceforge.net
Subject: RE: [f2fs-dev] [PATCH V2 RESEND] f2fs: check all ones or zeros
bitmap with bitops for better mount performance

Hi Lee,

> -----Original Message-----
> From: Changman Lee [mailto:cm224.lee@samsung.com]
> Sent: Tuesday, October 29, 2013 3:36 PM
> To: 'Chao Yu'; jaegeuk.kim@samsung.com
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Subject: RE: [f2fs-dev] [PATCH V2 RESEND] f2fs: check all ones or
> zeros
bitmap
> with bitops for better mount performance
>
> Review attached patch, please.

Could we hide the pre calculated value by generating it in allocated memory
by func, because the value will be no use after build_sit_entries();

Regards
Yu

>
> -----Original Message-----
> From: Chao Yu [mailto:chao2.yu@samsung.com]
> Sent: Tuesday, October 29, 2013 3:51 PM
> To: jaegeuk.kim@samsung.com
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Subject: [f2fs-dev] [PATCH V2 RESEND] 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.
>
> v1-->v2:
> use find_next_{zero_}bit_le for better performance and readable as
> Jaegeuk suggested.
> use neat logogram in comment as Gu Zheng suggested.
> search continuous ones or zeros for better performance when checking

> mixed bitmap.
>
> Suggested-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> Signed-off-by: Shu Tan <shu.tan@samsung.com>
> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> ---
> fs/f2fs/segment.h | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index
> abe7094..a7abfa8
> 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -550,8 +550,9 @@ 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;
> + bool is_valid = test_bit_le(0, raw_sit->valid_map) ? true : false;
> int valid_blocks = 0;
> - int i;
> + int cur_pos = 0, next_pos;
>
> /* check segment usage */
> BUG_ON(GET_SIT_VBLOCKS(raw_sit) > sbi->blocks_per_seg); @@ -560,9
> +561,19 @@ 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++;
> + 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); }
>
> --
> 1.7.9.5
>
>
>
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