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From: Chao Yu <chao2.yu@samsung.com>
To: jaegeuk.kim@samsung.com
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Subject: RE: [f2fs-dev] [PATCH V3 2/2] f2fs: read contiguous sit entry pages by
 merging for mount performance
Date: Sat, 23 Nov 2013 10:53:16 +0800
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Hi,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@samsung.com]
> Sent: Friday, November 22, 2013 5:11 PM
> To: Chao Yu
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net; 谭姝
> Subject: Re: [f2fs-dev] [PATCH V3 2/2] f2fs: read contiguous sit entry pages by merging for mount performance
> 
> Hi,
> 
> Just one niptick.
> 
> 2013-11-22 (금), 09:09 +0800, Chao Yu:
> > Previously we read sit entries page one by one, this method lost the chance
> > of reading contiguous page together. So we read pages as contiguous as
> > possible for better mount performance.
> >
> > change log:
> >  o merge judgements/use 'Continue' or 'Break' instead of 'Goto' as Gu Zheng
> >    suggested.
> >  o add mark_page_accessed() before release page to delay VM reclaiming.
> >  o remove '*order' for simplification of function as Jaegeuk Kim suggested.
> >
> > Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> > ---
> >  fs/f2fs/segment.c |  103 +++++++++++++++++++++++++++++++++++++++--------------
> >  fs/f2fs/segment.h |    2 ++
> >  2 files changed, 78 insertions(+), 27 deletions(-)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 8149eba..998e7d3 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/blkdev.h>
> >  #include <linux/prefetch.h>
> >  #include <linux/vmalloc.h>
> > +#include <linux/swap.h>
> >
> >  #include "f2fs.h"
> >  #include "segment.h"
> > @@ -1488,41 +1489,89 @@ static int build_curseg(struct f2fs_sb_info *sbi)
> >  	return restore_curseg_summaries(sbi);
> >  }
> >
> > +static int ra_sit_pages(struct f2fs_sb_info *sbi, int start, int nrpages)
> > +{
> > +	struct address_space *mapping = sbi->meta_inode->i_mapping;
> > +	struct page *page;
> > +	block_t blk_addr, prev_blk_addr = 0;
> > +	int sit_blk_cnt = SIT_BLK_CNT(sbi);
> 
> Can we remove SIT_BLK_CNT by replacing with sit_i->sit_blocks?

Because sit_i->sit_blocks is a multiple of segment size(i.e. 512/1024),
but we may use part of sit_blocks, not all of them. So it's waste to read 
all of them.
What's your opinion?

Regards,
Yu

> 
> --
> Jaegeuk Kim
> Samsung