linux-ext4 - Re: [PATCH 3/3] e2fsck: optimize CPU usage in check_{block,inode}

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Message-ID: <alpine.LFD.2.00.1203120844340.5543@dhcp-27-109.brq.redhat.com>
Date:	Mon, 12 Mar 2012 08:44:45 +0100 (CET)
From:	Lukas Czerner <lczerner@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>
cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	lczerner@...hat.com
Subject: Re: [PATCH 3/3] e2fsck: optimize CPU usage in
 check_{block,inode}_bitmaps()

On Sun, 11 Mar 2012, Theodore Ts'o wrote:

> The boolean expression (!skip_group || csum_flag) is always true,
> since if csum_flag is FALSE, skip_group must also be FALSE.  Hence, we
> can just remove the expression from the conditional altogether, thus
> simplifying the code and making it easier to read/understand.
> 
> Also, in the case where the bit is set in the bitmap, there's no point
> repeatedly setting first_free to be ext2fs_block_count(fs->super).
> 
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>

Looks good, thanks!
-Lukas

> ---
>  e2fsck/pass5.c |   11 +++++------
>  1 files changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/e2fsck/pass5.c b/e2fsck/pass5.c
> index e25f080..c121d92 100644
> --- a/e2fsck/pass5.c
> +++ b/e2fsck/pass5.c
> @@ -372,15 +372,14 @@ redo_counts:
>  		ctx->options &= ~E2F_OPT_DISCARD;
>  
>  	do_counts:
> -		if (!bitmap && (!skip_group || csum_flag)) {
> +		if (!bitmap) {
>  			group_free++;
>  			free_blocks++;
>  			if (first_free > i)
>  				first_free = i;
> -		} else {
> -			if (i > first_free)
> -				e2fsck_discard_blocks(ctx, first_free,
> -						      (i - first_free));
> +		} else if (i > first_free) {
> +			e2fsck_discard_blocks(ctx, first_free,
> +					      (i - first_free));
>  			first_free = ext2fs_blocks_count(fs->super);
>  		}
>  		blocks ++;
> @@ -627,7 +626,7 @@ do_counts:
>  						      inodes - first_free);
>  				first_free = fs->super->s_inodes_per_group + 1;
>  			}
> -		} else if (!skip_group || csum_flag) {
> +		} else {
>  			group_free++;
>  			free_inodes++;
>  			if (first_free > inodes)
> 

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