kernel-ark/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
Makefile
vxfs_bmap.c
vxfs_dir.h
vxfs_extern.h convert remaining ->clear_inode() to ->evict_inode() 2010-08-09 16:48:37 -04:00
vxfs_fshead.c
vxfs_fshead.h
vxfs_immed.c
vxfs_inode.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
vxfs_inode.h
vxfs_lookup.c BKL: remove BKL from freevxfs 2010-10-21 18:48:09 +02:00
vxfs_olt.c
vxfs_olt.h
vxfs_subr.c
vxfs_super.c new helper: mount_bdev() 2010-10-29 04:16:13 -04:00
vxfs.h