Re: [PATCH V2] f2fs: check all ones or zeros bitmap with bitops for better mount performance

[Chao Yu <chao2.yu@samsung.com>]

Hi Gu,

> -----Original Message-----
> From: Gu Zheng [mailto:guz.fnst@cn.fujitsu.com]
> Sent: Thursday, October 24, 2013 6:04 PM
> To: Chao Yu
> Cc: jaegeuk.kim@samsung.com; linux-fsdevel@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; '谭姝'
> Subject: Re: [f2fs-dev] [PATCH V2] f2fs: check all ones or zeros bitmap with
> bitops for better mount performance
> 
> 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.
It seems more neat. I will take it, thanks.

> 
> Regards,
> Gu
> 
> >
> > Suggested-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
> > Signed-off-by: Tan Shu <shu.tan@samsung.com>
> > Signed-off-by: Yu Chao <chao2.yu@samsung.com>
> > ---
> >  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))



------------------------------------------------------------------------------
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@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel