linux-kernel - Re: [PATCH 4/4] f2fs: optimize build_free

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Date:	Tue, 07 May 2013 19:33:59 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Haicheng Li <haicheng.li@...ux.intel.com>
Cc:	linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, Haicheng Li <haicheng.lee@...il.com>
Subject: Re: [PATCH 4/4] f2fs: optimize build_free_nids()

Hi,

2013-05-06 (월), 23:15 +0800, Haicheng Li:
> When nm_i->fcnt > 2 * MAX_FREE_NIDS, stop scanning other NAT pages.
> 
> Signed-off-by: Haicheng Li <haicheng.li@...ux.intel.com>
> ---
>  fs/f2fs/node.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 1fe3fe2..3136224 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1342,6 +1342,8 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
>  		if (nid >= nm_i->max_nid)
>  			nid = 0;
>  
> +		if (nm_i->fcnt > 2 * MAX_FREE_NIDS)
> +			break;

Could you explain when this can happen?

IMO, this is an unnecessary condition check, since the below condition
that includes FREE_NID_PAGES already limits the number of free nids.
Thanks,

>  		if (i++ == FREE_NID_PAGES)
>  			break;
>  	}

-- 
Jaegeuk Kim
Samsung

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