linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: merge read IOs at ra_nat

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Date:	Sun, 24 Nov 2013 11:46:57 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Changman Lee <cm224.lee@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: merge read IOs at ra_nat_pages()

Hi,

2013-11-22 (금), 12:41 +0900, Changman Lee:
> How about doing mark_page_accessed(page) in ra_nat_pages like
> ra_sit_pages to prevent readahead pages are reclaimed by VM?

Agreed.
I'll modify and merge this.
Thanks,

> 
> On 목, 2013-11-21 at 18:35 +0900, Jaegeuk Kim wrote:
> > This patch changes the policy of submitting read bios at ra_nat_pages.
> > 
> > Previously, f2fs submits small read bios with block plugging.
> > But, with this patch, f2fs itself merges read bios first and then submits a
> > large bio, which can reduce the bio handling overheads.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
> > ---
> >  fs/f2fs/node.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> > 
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index b843a5b..c06871f 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -89,13 +89,10 @@ static void ra_nat_pages(struct f2fs_sb_info *sbi, int nid)
> >  {
> >  	struct address_space *mapping = sbi->meta_inode->i_mapping;
> >  	struct f2fs_nm_info *nm_i = NM_I(sbi);
> > -	struct blk_plug plug;
> >  	struct page *page;
> >  	pgoff_t index;
> >  	int i;
> >  
> > -	blk_start_plug(&plug);
> > -
> >  	for (i = 0; i < FREE_NID_PAGES; i++, nid += NAT_ENTRY_PER_BLOCK) {
> >  		if (nid >= nm_i->max_nid)
> >  			nid = 0;
> > @@ -108,12 +105,11 @@ static void ra_nat_pages(struct f2fs_sb_info *sbi, int nid)
> 
> mark_page_accessed(page);
> 
> >  			f2fs_put_page(page, 1);
> >  			continue;
> >  		}
> > -		if (f2fs_readpage(sbi, page, index, READ))
> > -			continue;
> > +		submit_read_page(sbi, page, index, READ_SYNC);
> >  
> 
> mark_page_accessed(page);
> 
> >  		f2fs_put_page(page, 0);
> >  	}
> > -	blk_finish_plug(&plug);
> > +	f2fs_submit_read_bio(sbi, READ_SYNC);
> >  }
> >  
> >  static struct nat_entry *__lookup_nat_cache(struct f2fs_nm_info *nm_i, nid_t n)
> 
> 
> --
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-- 
Jaegeuk Kim
Samsung

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