linux-sg2042/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
..
Kconfig Revert "lib: build list_sort() only if needed" 2010-03-07 09:54:44 -08:00
Makefile
budget.c writeback: enforce s_umount locking in writeback_inodes_sb 2010-06-11 12:58:07 +02:00
commit.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
compress.c UBIFS: fix sparse warnings 2008-12-31 14:13:24 +02:00
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 UBIFS: improve find function interface 2009-03-08 13:29:09 +02:00
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 headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
journal.c UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
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 UBIFS: improve lprops dump 2009-09-15 17:09:48 +03:00
lpt.c UBIFS: check return code of ubifs_lpt_lookup 2010-09-07 12:09:41 +03:00
lpt_commit.c UBIFS: check return code of pnode_lookup 2010-09-07 12:10:43 +03:00
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 UBIFS: check ubifs_scan error codes better 2009-09-10 12:06:47 +03:00
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.c UBIFS: mark unused key objects as invalid 2010-08-30 10:19:08 +03:00
tnc_commit.c UBIFS: do not print scary error messages needlessly 2009-09-10 12:06:47 +03:00
tnc_misc.c UBIFS: correct key comparison 2008-09-30 11:12:57 +03:00
ubifs-media.h UBIFS: define journal head numbers in ubifs-media.h 2009-09-15 14:45:35 +03:00
ubifs.h UBIFS: introduce new flags for RO mounts 2010-09-19 21:07:58 +03:00
xattr.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00