[PATCH v2] xfs: improve xfs_iext_destroy() by freeing extent indirection array directly

[PATCH v2] xfs: improve xfs_iext_destroy() by freeing extent indirection array directly

[Jeff Liu]

From: Jie Liu <jeff.liu@oracle.com>

To free the incore file extents stores at an indirection array, we
call the common routine xfs_iext_irec_remove() to remove a record
from the array one at a time in reverse order, which will resize an
extent indirection array repeatedly according to the array size.

This is inefficient for dealing with a file with thousands of incore
extent records stores at indirection arrays.

This patch improve this kind of things by freeing the extent records
from the indirection array directly so that we can get benefits for
reducing the overhead of alloc/free buffers which is depending on the
number of extents records.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
v2:
- revise the commit message, no memory fragments at all.

 fs/xfs/xfs_inode_fork.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_inode_fork.c b/fs/xfs/xfs_inode_fork.c
index 02f1083..ba70f98 100644
--- a/fs/xfs/xfs_inode_fork.c
+++ b/fs/xfs/xfs_inode_fork.c
@@ -1525,9 +1525,12 @@ xfs_iext_destroy(
 		int	nlists;
 
 		nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ;
-		for (erp_idx = nlists - 1; erp_idx >= 0 ; erp_idx--) {
-			xfs_iext_irec_remove(ifp, erp_idx);
+		for (erp_idx = 0; erp_idx < nlists; erp_idx++) {
+			xfs_ext_irec_t	*erp = &ifp->if_u1.if_ext_irec[erp_idx];
+			if (erp->er_extbuf)
+				kmem_free(erp->er_extbuf);
 		}
+		kmem_free(ifp->if_u1.if_ext_irec);
 		ifp->if_flags &= ~XFS_IFEXTIREC;
 	} else if (ifp->if_real_bytes) {
 		kmem_free(ifp->if_u1.if_extents);
-- 1.7.9.5 

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Re: [PATCH v2] xfs: improve xfs_iext_destroy() by freeing extent indirection array directly

[Dave Chinner]

On Tue, Sep 24, 2013 at 10:06:03PM +0800, Jeff Liu wrote:
> From: Jie Liu <jeff.liu@oracle.com>
> 
> To free the incore file extents stores at an indirection array, we
> call the common routine xfs_iext_irec_remove() to remove a record
> from the array one at a time in reverse order, which will resize an
> extent indirection array repeatedly according to the array size.
> 
> This is inefficient for dealing with a file with thousands of incore
> extent records stores at indirection arrays.
> 
> This patch improve this kind of things by freeing the extent records
> from the indirection array directly so that we can get benefits for
> reducing the overhead of alloc/free buffers which is depending on the
> number of extents records.
> 
> Signed-off-by: Jie Liu <jeff.liu@oracle.com>

Looks good.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
-- 
Dave Chinner
david@fromorbit.com

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