linux-sg2042/fs/freevxfs
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 fs/Kconfig: move vxfs out 2009-01-22 13:15:58 +03:00
Makefile Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vxfs.h [PATCH] inode_diet: Replace inode.u.generic_ip with inode.i_private 2006-09-27 08:26:17 -07:00
vxfs_bmap.c freevxfs: possible null pointer dereference fix 2007-05-08 11:14:59 -07:00
vxfs_dir.h fs/: Spelling fixes 2008-02-03 17:33:42 +02:00
vxfs_extern.h convert remaining ->clear_inode() to ->evict_inode() 2010-08-09 16:48:37 -04:00
vxfs_fshead.c [PATCH] fs/freevxfs: cleanup of spelling errors 2006-06-25 10:01:01 -07:00
vxfs_fshead.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vxfs_immed.c fs/freevxfs/: proper externs 2008-04-29 08:06:00 -07:00
vxfs_inode.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
vxfs_inode.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vxfs_lookup.c BKL: remove BKL from freevxfs 2010-10-21 18:48:09 +02:00
vxfs_olt.c BUG_ON() Conversion in fs/freevxfs/ 2006-04-02 13:41:02 +02:00
vxfs_olt.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vxfs_subr.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
vxfs_super.c new helper: mount_bdev() 2010-10-29 04:16:13 -04:00