linux-kernel - RE: [f2fs-dev] [PATCH V3 2/2] f2fs: read contiguous sit entry pages by merging for mount performance

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Date:	Sun, 24 Nov 2013 13:05:26 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Chao Yu <chao2.yu@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	'谭姝' <shu.tan@...sung.com>
Subject: RE: [f2fs-dev] [PATCH V3 2/2] f2fs: read contiguous sit entry pages by
 merging for mount performance

Hi,

2013-11-23 (토), 10:53 +0800, Chao Yu:
> Hi,
> 
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk.kim@...sung.com]
> > Sent: Friday, November 22, 2013 5:11 PM
> > To: Chao Yu
> > Cc: linux-fsdevel@...r.kernel.org; linux-kernel@...r.kernel.org; linux-f2fs-devel@...ts.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@...sung.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?

Got it.
It's right and we can avoid that.
Thanks, :)

-- 
Jaegeuk Kim
Samsung

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