Ocfs2 devel - Jul 2016 - [PATCH v2] ocfs2: improve recovery performance

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 |   42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index e607419cdfa4..67179cf60525 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 +1172,35 @@ 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;
+			p_blkno++;
 		}
 
 		v_blkno += p_blocks;
 	}
 
 bail:
-	for(i = 0; i < CONCURRENT_JOURNAL_FILL; i++)
-		brelse(bhs[i]);
 	return status;
 }
 
-- 
1.7.9.5

On Thu,  7 Jul 2016 10:24:48 +0800 Junxiao Bi <junxiao.bi at oracle.com>
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.
So since v1 you did this (unchangelogged bugfix!):

--- a/fs/ocfs2/journal.c~ocfs2-improve-recovery-performance-v2
+++ a/fs/ocfs2/journal.c
@@ -1194,6 +1194,7 @@ static int ocfs2_force_read_journal(stru
 
 			brelse(bh);
 			bh = NULL;
+			p_blkno++;
 		}
 
 		v_blkno += p_blocks;


I suppose this is a bit neater?

--- a/fs/ocfs2/journal.c~ocfs2-improve-recovery-performance-v2-fix
+++ a/fs/ocfs2/journal.c
@@ -1172,14 +1172,12 @@ static int ocfs2_force_read_journal(stru
 			goto bail;
 		}
 
-		for (i = 0; i < p_blocks; i++) {
+		for (i = 0; i < p_blocks; i++, p_blkno++) {
 			bh = __find_get_block(osb->sb->s_bdev, p_blkno,
 					osb->sb->s_blocksize);
 			/* block not cached. */
-			if (!bh) {
-				p_blkno++;
+			if (!bh)
 				continue;
-			}
 
 			brelse(bh);
 			bh = NULL;
@@ -1194,7 +1192,6 @@ static int ocfs2_force_read_journal(stru
 
 			brelse(bh);
 			bh = NULL;
-			p_blkno++;
 		}
 
 		v_blkno += p_blocks;
_