linux.git/include/trace/events/ext4.h, branch v3.10

ext4: fix fio regression

2013-05-03T06:15:52+00:00

We (Linux Kernel Performance project) found a regression introduced
by commit:

  f7fec032aa ext4: track all extent status in extent status tree

The commit causes about 20% performance decrease in fio random write
test. Profiler shows that rb_next() uses a lot of CPU time. The call
stack is:

  rb_next
  ext4_es_find_delayed_extent
  ext4_map_blocks
  _ext4_get_block
  ext4_get_block_write
  __blockdev_direct_IO
  ext4_direct_IO
  generic_file_direct_write
  __generic_file_aio_write
  ext4_file_write
  aio_rw_vect_retry
  aio_run_iocb
  do_io_submit
  sys_io_submit
  system_call_fastpath
  io_submit
  td_io_getevents
  io_u_queued_complete
  thread_main
  main
  __libc_start_main

The cause is that ext4_es_find_delayed_extent() doesn't have an
upper bound, it keeps searching until a delayed extent is found.
When there are a lots of non-delayed entries in the extent state
tree, ext4_es_find_delayed_extent() may uses a lot of CPU time.

Reported-by: LKP project 
Signed-off-by: Yan, Zheng 
Signed-off-by: Zheng Liu 
Cc: "Theodore Ts'o"

ext4: fix miscellaneous big endian warnings

2013-04-10T03:59:55+00:00

None of these result in any bug, but they makes sparse complain.

Signed-off-by: "Theodore Ts'o"

ext4: collapse handling of data=ordered and data=writeback codepaths

2013-04-03T16:39:17+00:00

The only difference between how we handle data=ordered and
data=writeback is a single call to ext4_jbd2_file_inode().  Eliminate
code duplication by factoring out redundant the code paths.

Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Lukas Czerner

ext4: optimize ext4_es_shrink()

2013-03-01T04:58:56+00:00

When the system is under memory pressure, ext4_es_srhink() will get
called very often.  So optimize returning the number of items in the
file system's extent status cache by keeping a per-filesystem count,
instead of calculating it each time by scanning all of the inodes in
the extent status cache.

Also rename the slab used for the extent status cache to be
"ext4_extent_status" so it's obviousl the slab in question is created
by ext4.

Signed-off-by: "Theodore Ts'o" 
Cc: Zheng Liu

ext4: reclaim extents from extent status tree

2013-02-18T05:32:55+00:00

Although extent status is loaded on-demand, we also need to reclaim
extent from the tree when we are under a heavy memory pressure because
in some cases fragmented extent tree causes status tree costs too much
memory.

Here we maintain a lru list in super_block.  When the extent status of
an inode is accessed and changed, this inode will be move to the tail
of the list.  The inode will be dropped from this list when it is
cleared.  In the inode, a counter is added to count the number of
cached objects in extent status tree.  Here only written/unwritten/hole
extent is counted because delayed extent doesn't be reclaimed due to
fiemap, bigalloc and seek_data/hole need it.  The counter will be
increased as a new extent is allocated, and it will be decreased as a
extent is freed.

In this commit we use normal shrinker framework to reclaim memory from
the status tree.  ext4_es_reclaim_extents_count() traverses the lru list
to count the number of reclaimable extents.  ext4_es_shrink() tries to
reclaim written/unwritten/hole extents from extent status tree.  The
inode that has been shrunk is moved to the tail of lru list.

Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o" 
Cc: Jan kara

ext4: lookup block mapping in extent status tree

2013-02-18T05:29:59+00:00

After tracking all extent status, we already have a extent cache in
memory.  Every time we want to lookup a block mapping, we can first
try to lookup it in extent status tree to avoid a potential disk I/O.

A new function called ext4_es_lookup_extent is defined to finish this
work.  When we try to lookup a block mapping, we always call
ext4_map_blocks and/or ext4_da_map_blocks.  So in these functions we
first try to lookup a block mapping in extent status tree.

A new flag EXT4_GET_BLOCKS_NO_PUT_HOLE is used in ext4_da_map_blocks
in order not to put a hole into extent status tree because this hole
will be converted to delayed extent in the tree immediately.

Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o" 
Cc: Jan kara

ext4: rename and improbe ext4_es_find_extent()

2013-02-18T05:27:26+00:00

This commit renames ext4_es_find_extent with ext4_es_find_delayed_extent
and improve this function.  First, we split input and output parameter.
Second, this function never return the first block of the next delayed
extent after 'es'.

Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o" 
Cc: Jan kara

ext4: add physical block and status member into extent status tree

2013-02-18T05:26:51+00:00

This commit adds two members in extent_status structure to let it record
physical block and extent status.  Here es_pblk is used to record both
of them because physical block only has 48 bits.  So extent status could
be stashed into it so that we can save some memory.  Now written,
unwritten, delayed and hole are defined as status.

Due to new member is added into extent status tree, all interfaces need
to be adjusted.

Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Jan Kara

ext4: refine extent status tree

2013-02-18T05:26:51+00:00

This commit refines the extent status tree code.

1) A prefix 'es_' is added to to the extent status tree structure
members.

2) Refactored es_remove_extent() so that __es_remove_extent() can be
used by es_insert_extent() to remove the old extent entry(-ies) before
inserting a new one.

3) Rename extent_status_end() to ext4_es_end()

4) ext4_es_can_be_merged() is define to check whether two extents can
be merged or not.

5) Update and clarified comments.

Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Jan Kara

ext4: add tracepoint in punching hole

2013-01-17T01:21:26+00:00

This patch adds a tracepoint in ext4_punch_hole.

CC: Lukas Czerner 
Signed-off-by: Zheng Liu 
Signed-off-by: "Theodore Ts'o"