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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
..
9p fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
adfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
affs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
afs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
autofs4 fs: dcache remove dcache_lock 2011-01-07 17:50:23 +11:00
befs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
bfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
btrfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
cachefiles llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
ceph fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
cifs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
coda fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
configfs fs: dcache rationalise dget variants 2011-01-07 17:50:24 +11:00
cramfs new helper: mount_bdev() 2010-10-29 04:16:13 -04:00
debugfs convert get_sb_single() users 2010-10-29 04:16:28 -04:00
devpts convert get_sb_single() users 2010-10-29 04:16:28 -04:00
dlm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm 2010-10-22 17:33:16 -07:00
ecryptfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
efs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
exofs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
exportfs fs: dcache rationalise dget variants 2011-01-07 17:50:24 +11:00
ext2 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
ext3 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
ext4 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
fat fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
freevxfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
fscache
fuse fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
gfs2 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hfsplus fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hostfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hpfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hppfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hugetlbfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
isofs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
jbd 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
jbd2 jbd2: fix /proc/fs/jbd2/<dev> when using an external journal 2010-11-17 21:46:26 -05:00
jffs2 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
jfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
lockd BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
logfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
minix fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
ncpfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
nfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
nfs_common
nfsd fs: dcache scale dentry refcount 2011-01-07 17:50:21 +11:00
nilfs2 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
nls
notify fs: dcache remove dcache_lock 2011-01-07 17:50:23 +11:00
ntfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
ocfs2 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
omfs new helper: mount_bdev() 2010-10-29 04:16:13 -04:00
openpromfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
partitions Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block 2010-10-25 07:45:10 -07:00
proc fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
qnx4 fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
quota quota: Fix possible oops in __dquot_initialize() 2010-10-28 01:30:06 +02:00
ramfs convert get_sb_nodev() users 2010-10-29 04:16:31 -04:00
reiserfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
romfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
squashfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
sysfs fs: change d_delete semantics 2011-01-07 17:50:18 +11:00
sysv fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
ubifs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
udf fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
ufs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
xfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
aio.c new helper: ihold() 2010-10-25 21:26:11 -04:00
anon_inodes.c convert get_sb_pseudo() users 2010-10-29 04:16:33 -04:00
attr.c
bad_inode.c
binfmt_aout.c Don't dump task struct in a.out core-dumps 2010-10-14 10:57:40 -07:00
binfmt_elf_fdpic.c
binfmt_elf.c
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c convert get_sb_single() users 2010-10-29 04:16:28 -04:00
binfmt_script.c
binfmt_som.c
bio-integrity.c
bio.c bio: take care not overflow page count when mapping/copying user data 2010-11-10 14:40:43 +01:00
block_dev.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
buffer.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2010-10-26 17:58:44 -07:00
char_dev.c Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl 2010-10-22 10:52:56 -07:00
compat_binfmt_elf.c
compat_ioctl.c BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
compat.c exec: copy-and-paste the fixes into compat_do_execve() paths 2010-11-30 17:56:38 -08:00
dcache.c fs: consolidate dentry kill sequence 2011-01-07 17:50:25 +11:00
dcookies.c
direct-io.c fs/direct-io.c: fix truncation error in dio_complete() return 2010-10-26 16:52:13 -07:00
drop_caches.c
eventfd.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
eventpoll.c epoll: make epoll_wait() use the hrtimer range feature 2010-10-27 18:03:18 -07:00
exec.c install_special_mapping skips security_file_mmap check. 2010-12-15 12:30:36 -08:00
fcntl.c fasync: Fix placement of FASYNC flag comment 2010-10-27 18:17:02 -07:00
fifo.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
file_table.c fs: allow for more than 2^31 files 2010-10-26 16:52:15 -07:00
file.c
filesystems.c
fs_struct.c
fs-writeback.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2010-10-30 09:05:48 -07:00
generic_acl.c
inode.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
internal.h braino in internal.h 2010-10-29 05:49:13 -04:00
ioctl.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2010-11-19 19:46:45 -08:00
ioprio.c ioprio: grab rcu_read_lock in sys_ioprio_{set,get}() 2010-11-15 10:23:31 +01:00
Kconfig Merge 'staging-next' to Linus's tree 2010-10-28 09:44:56 -07:00
Kconfig.binfmt coredump: default CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS=y 2010-10-27 18:03:12 -07:00
libfs.c fs: dcache remove dcache_lock 2011-01-07 17:50:23 +11:00
locks.c fs: dcache scale dentry refcount 2011-01-07 17:50:21 +11:00
Makefile Merge 'staging-next' to Linus's tree 2010-10-28 09:44:56 -07:00
mbcache.c
mpage.c
namei.c fs: dcache remove dcache_lock 2011-01-07 17:50:23 +11:00
namespace.c BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
nfsctl.c
no-block.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
open.c fix open/umount race 2010-10-29 04:14:56 -04:00
pipe.c Un-inline get_pipe_info() helper function 2010-11-28 16:27:19 -08:00
pnode.c
pnode.h
posix_acl.c
read_write.c BKL: remove extraneous #include <smp_lock.h> 2010-11-17 08:59:32 -08:00
read_write.h
readdir.c
select.c epoll: make epoll_wait() use the hrtimer range feature 2010-10-27 18:03:18 -07:00
seq_file.c fs: take dcache_lock inside __d_path 2010-10-25 21:26:12 -04:00
signalfd.c Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 2010-10-26 10:13:10 -07:00
splice.c Export 'get_pipe_info()' to other users 2010-11-28 14:09:57 -08:00
stack.c
stat.c
statfs.c
super.c switch get_sb_ns() users 2010-10-29 04:17:03 -04:00
sync.c
timerfd.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
utimes.c
xattr_acl.c
xattr.c