[Ocfs2-devel] [PATCH v2] ocfs2: improve recovery performance

[xuejiufei]

Hi Junxiao,
p_blkno is not increased after force reading from disk, so
this block is read many times from disk while other blocks
remain in cached are not reloaded.

Thanks,
Jiufei

On 2016/6/17 17:28, Junxiao Bi wrote:
> Journal replay will be run when do recovery for a dead node,
> to avoid the stale cache impact, all blocks of dead node's
> journal inode were reload from disk. This hurts the performance,
> check whether one block is cached before reload it can improve
> a lot performance. In my test env, the time doing recovery was
> improved from 120s to 1s.
> 
> Signed-off-by: Junxiao Bi <junxiao.bi at oracle.com>
> ---
>  fs/ocfs2/journal.c |   41 ++++++++++++++++++++++-------------------
>  1 file changed, 22 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index e607419cdfa4..bc0e21e8a674 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -1159,10 +1159,8 @@ static int ocfs2_force_read_journal(struct inode *inode)
>  	int status = 0;
>  	int i;
>  	u64 v_blkno, p_blkno, p_blocks, num_blocks;
> -#define CONCURRENT_JOURNAL_FILL 32ULL
> -	struct buffer_head *bhs[CONCURRENT_JOURNAL_FILL];
> -
> -	memset(bhs, 0, sizeof(struct buffer_head *) * CONCURRENT_JOURNAL_FILL);
> +	struct buffer_head *bh = NULL;
> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  
>  	num_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
>  	v_blkno = 0;
> @@ -1174,29 +1172,34 @@ static int ocfs2_force_read_journal(struct inode *inode)
>  			goto bail;
>  		}
>  
> -		if (p_blocks > CONCURRENT_JOURNAL_FILL)
> -			p_blocks = CONCURRENT_JOURNAL_FILL;
> +		for (i = 0; i < p_blocks; i++) {
> +			bh = __find_get_block(osb->sb->s_bdev, p_blkno,
> +					osb->sb->s_blocksize);
> +			/* block not cached. */
> +			if (!bh) {
> +				p_blkno++;
> +				continue;
> +			}
>  
> -		/* We are reading journal data which should not
> -		 * be put in the uptodate cache */
> -		status = ocfs2_read_blocks_sync(OCFS2_SB(inode->i_sb),
> -						p_blkno, p_blocks, bhs);
> -		if (status < 0) {
> -			mlog_errno(status);
> -			goto bail;
> -		}
> +			brelse(bh);
> +			bh = NULL;
> +			/* We are reading journal data which should not
> +			 * be put in the uptodate cache.
> +			 */
> +			status = ocfs2_read_blocks_sync(osb, p_blkno, 1, &bh);
> +			if (status < 0) {
> +				mlog_errno(status);
> +				goto bail;
> +			}
>  
> -		for(i = 0; i < p_blocks; i++) {
> -			brelse(bhs[i]);
> -			bhs[i] = NULL;
> +			brelse(bh);
> +			bh = NULL;
>  		}
>  
>  		v_blkno += p_blocks;
>  	}
>  
>  bail:
> -	for(i = 0; i < CONCURRENT_JOURNAL_FILL; i++)
> -		brelse(bhs[i]);
>  	return status;
>  }
>  
>