1
linux/fs/jfs
Nick Piggin fa0d7e3de6 fs: icache RCU free inodes
RCU free the struct inode. This will allow:

- Subsequent store-free path walking patch. The inode must be consulted for
  permissions when walking, so an RCU inode reference is a must.
- sb_inode_list_lock to be moved inside i_lock because sb list walkers who want
  to take i_lock no longer need to take sb_inode_list_lock to walk the list in
  the first place. This will simplify and optimize locking.
- Could remove some nested trylock loops in dcache code
- Could potentially simplify things a bit in VM land. Do not need to take the
  page lock to follow page->mapping.

The downsides of this is the performance cost of using RCU. In a simple
creat/unlink microbenchmark, performance drops by about 10% due to inability to
reuse cache-hot slab objects. As iterations increase and RCU freeing starts
kicking over, this increases to about 20%.

In cases where inode lifetimes are longer (ie. many inodes may be allocated
during the average life span of a single inode), a lot of this cache reuse is
not applicable, so the regression caused by this patch is smaller.

The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU,
however this adds some complexity to list walking and store-free path walking,
so I prefer to implement this at a later date, if it is shown to be a win in
real situations. I haven't found a regression in any non-micro benchmark so I
doubt it will be a problem.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:26 +11:00
..
acl.c
endian24.h
file.c remove inode_setattr 2010-08-09 16:47:37 -04:00
inode.c switch jfs to ->evict_inode() 2010-08-09 16:48:17 -04:00
ioctl.c
jfs_acl.h
jfs_btree.h
jfs_debug.c
jfs_debug.h
jfs_dinode.h
jfs_dmap.c
jfs_dmap.h
jfs_dtree.c
jfs_dtree.h
jfs_extent.c
jfs_extent.h
jfs_filsys.h
jfs_imap.c list.h: new helper - hlist_add_fake() 2010-10-25 21:24:15 -04:00
jfs_imap.h
jfs_incore.h
jfs_inode.c jfs: replace inode uid,gid,mode init with helper 2010-05-21 18:31:23 -04:00
jfs_inode.h switch jfs to ->evict_inode() 2010-08-09 16:48:17 -04:00
jfs_lock.h
jfs_logmgr.c Fix various typos of valid in comments 2010-09-21 17:04:50 +02:00
jfs_logmgr.h
jfs_metapage.c
jfs_metapage.h
jfs_mount.c fix printk typo 'faild' 2010-08-09 11:25:17 +02:00
jfs_superblock.h
jfs_txnmgr.c new helper: ihold() 2010-10-25 21:26:11 -04:00
jfs_txnmgr.h
jfs_types.h
jfs_umount.c
jfs_unicode.c
jfs_unicode.h
jfs_uniupr.c
jfs_xattr.h
jfs_xtree.c
jfs_xtree.h
Kconfig
Makefile
namei.c fs: change d_hash for rcu-walk 2011-01-07 17:50:20 +11:00
resize.c
super.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
symlink.c
xattr.c jfs: don't allow os2 xattr namespace overlap with others 2010-08-10 15:33:09 -07:00