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Subject[RFC/PATCH] ext3: remove inode constructor
From: Pekka Enberg <penberg@cs.helsinki.fi>

As explained by Christoph Lameter, ext3_alloc_inode() touches the same
cache line as init_once() so we gain nothing from using slab
constructors. The SLUB allocator will be more effective without it
(free pointer can be placed inside the free'd object), so move inode
initialization to ext3_alloc_inode completely.

[postmark: numbers = 10000, transactions = 10000, 2 GHz Pentium M]

2.6.21 vanilla:

real 0m19.006s
user 0m0.144s
sys 0m7.424s

real 0m9.040s
user 0m0.156s
sys 0m5.164s

real 0m8.939s
user 0m0.128s
sys 0m5.180s

2.6.21 + ext3-remove-inode-constructor:

real 0m19.176s
user 0m0.176s
sys 0m7.436s

real 0m9.030s
user 0m0.172s
sys 0m5.120s

real 0m8.966s
user 0m0.168s
sys 0m5.132s

Cc: Stephen C. Tweedie <sct@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger@clusterfs.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
---
fs/ext3/super.c | 30 ++++++++++++------------------
1 file changed, 12 insertions(+), 18 deletions(-)

Index: 2.6/fs/ext3/super.c
===================================================================
--- 2.6.orig/fs/ext3/super.c 2007-05-04 12:57:09.000000000 +0300
+++ 2.6/fs/ext3/super.c 2007-05-04 13:01:27.000000000 +0300
@@ -444,17 +444,26 @@ static struct kmem_cache *ext3_inode_cac
static struct inode *ext3_alloc_inode(struct super_block *sb)
{
struct ext3_inode_info *ei;
+ struct inode *inode;

ei = kmem_cache_alloc(ext3_inode_cachep, GFP_NOFS);
if (!ei)
return NULL;
+ INIT_LIST_HEAD(&ei->i_orphan);
+#ifdef CONFIG_EXT3_FS_XATTR
+ init_rwsem(&ei->xattr_sem);
+#endif
+ mutex_init(&ei->truncate_mutex);
#ifdef CONFIG_EXT3_FS_POSIX_ACL
ei->i_acl = EXT3_ACL_NOT_CACHED;
ei->i_default_acl = EXT3_ACL_NOT_CACHED;
#endif
ei->i_block_alloc_info = NULL;
- ei->vfs_inode.i_version = 1;
- return &ei->vfs_inode;
+
+ inode = &ei->vfs_inode;
+ inode_init_once(inode);
+ inode->i_version = 1;
+ return inode;
}

static void ext3_destroy_inode(struct inode *inode)
@@ -462,28 +471,13 @@ static void ext3_destroy_inode(struct in
kmem_cache_free(ext3_inode_cachep, EXT3_I(inode));
}

-static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
-{
- struct ext3_inode_info *ei = (struct ext3_inode_info *) foo;
-
- if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
- SLAB_CTOR_CONSTRUCTOR) {
- INIT_LIST_HEAD(&ei->i_orphan);
-#ifdef CONFIG_EXT3_FS_XATTR
- init_rwsem(&ei->xattr_sem);
-#endif
- mutex_init(&ei->truncate_mutex);
- inode_init_once(&ei->vfs_inode);
- }
-}
-
static int init_inodecache(void)
{
ext3_inode_cachep = kmem_cache_create("ext3_inode_cache",
sizeof(struct ext3_inode_info),
0, (SLAB_RECLAIM_ACCOUNT|
SLAB_MEM_SPREAD),
- init_once, NULL);
+ NULL, NULL);
if (ext3_inode_cachep == NULL)
return -ENOMEM;
return 0;
-
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