kernel-ark/fs/ubifs
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
..
budget.c
commit.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
compress.c
debug.c Merge branch 'linux-next' of git://git.infradead.org/ubifs-2.6 2010-10-22 16:34:03 -07:00
debug.h UBIFS: introduce list sorting debugging checks 2010-08-30 10:19:09 +03:00
dir.c new helper: ihold() 2010-10-25 21:26:11 -04:00
file.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
find.c
gc.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
io.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
ioctl.c
journal.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
Kconfig
key.h UBIFS: mark unused key objects as invalid 2010-08-30 10:19:08 +03:00
log.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
lprops.c
lpt_commit.c UBIFS: check return code of pnode_lookup 2010-09-07 12:10:43 +03:00
lpt.c UBIFS: check return code of ubifs_lpt_lookup 2010-09-07 12:09:41 +03:00
Makefile
master.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
misc.h UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
orphan.c
recovery.c UBIFS: add a commentary about log recovery 2010-10-17 15:57:40 +03:00
replay.c UBIFS: do not allocate unneeded scan buffer 2010-10-21 11:15:19 +03:00
sb.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
scan.c UBIFS: mark unused key objects as invalid 2010-08-30 10:19:08 +03:00
shrinker.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
super.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
tnc_commit.c
tnc_misc.c
tnc.c UBIFS: mark unused key objects as invalid 2010-08-30 10:19:08 +03:00
ubifs-media.h
ubifs.h UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
xattr.c