kernel_optimize_test/fs/ext3
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 ext3: update ctime when changing the file's permission by setfacl 2010-06-25 01:20:37 +02:00
acl.h ext[234]: move over to 'check_acl' permission model 2009-09-08 11:09:04 -07:00
balloc.c ext3: Update kernel-doc comments 2010-10-28 01:30:05 +02:00
bitmap.c
dir.c ext3 uses rb_node = NULL; to zero rb_root. 2010-05-27 17:39:36 +02:00
ext3_jbd.c
file.c dquot: cleanup dquot initialize routine 2010-03-05 00:20:30 +01:00
fsync.c block: remove BLKDEV_IFL_WAIT 2010-09-16 20:52:58 +02:00
hash.c ext3: Add support for non-native signed/unsigned htree hash algorithms 2008-10-28 13:21:55 -04:00
ialloc.c ext3: Fix lost extented attributes for inode with ino == 11 2010-10-05 12:20:23 +02:00
inode.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6 2010-10-27 20:13:18 -07:00
ioctl.c ext3: remove the BKL in ext3/ioctl.c 2009-04-02 19:04:52 -07:00
Kconfig ext3: default to ordered mode 2010-07-23 12:50:55 +02:00
Makefile
namei.c new helper: ihold() 2010-10-25 21:26:11 -04:00
namei.h
resize.c ext3: Fix debug messages in ext3_group_extend() 2010-10-28 01:30:05 +02:00
super.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
symlink.c ext3: symlink must be handled via filesystem specific operation 2010-04-12 21:11:39 +02:00
xattr_security.c ext3: constify xattr handlers 2010-05-21 18:31:19 -04:00
xattr_trusted.c ext3: constify xattr handlers 2010-05-21 18:31:19 -04:00
xattr_user.c ext3: constify xattr handlers 2010-05-21 18:31:19 -04:00
xattr.c mbcache: Remove unused features 2010-08-09 16:48:45 -04:00
xattr.h ext3: constify xattr handlers 2010-05-21 18:31:19 -04:00