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

> -----Original Message-----
> From: Changman Lee [mailto:cm224.lee@samsung.com]
> Sent: Wednesday, October 30, 2013 7:25 AM
> 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
>
>
> As you know, if any data or function are used once, we can use some keywords
> like __initdata for data and __init for function.

Thanks for reminding me that.
I just think of that generating tmp data by func could save memory use or keep program
size small.

Regards
Yu

>
>
> -----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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> > lktr
> > k
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel



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