linux/fs/btrfs
Miao Xie 16cdcec736 btrfs: implement delayed inode items operation
Changelog V5 -> V6:
- Fix oom when the memory load is high, by storing the delayed nodes into the
  root's radix tree, and letting btrfs inodes go.

Changelog V4 -> V5:
- Fix the race on adding the delayed node to the inode, which is spotted by
  Chris Mason.
- Merge Chris Mason's incremental patch into this patch.
- Fix deadlock between readdir() and memory fault, which is reported by
  Itaru Kitayama.

Changelog V3 -> V4:
- Fix nested lock, which is reported by Itaru Kitayama, by updating space cache
  inode in time.

Changelog V2 -> V3:
- Fix the race between the delayed worker and the task which does delayed items
  balance, which is reported by Tsutomu Itoh.
- Modify the patch address David Sterba's comment.
- Fix the bug of the cpu recursion spinlock, reported by Chris Mason

Changelog V1 -> V2:
- break up the global rb-tree, use a list to manage the delayed nodes,
  which is created for every directory and file, and used to manage the
  delayed directory name index items and the delayed inode item.
- introduce a worker to deal with the delayed nodes.

Compare with Ext3/4, the performance of file creation and deletion on btrfs
is very poor. the reason is that btrfs must do a lot of b+ tree insertions,
such as inode item, directory name item, directory name index and so on.

If we can do some delayed b+ tree insertion or deletion, we can improve the
performance, so we made this patch which implemented delayed directory name
index insertion/deletion and delayed inode update.

Implementation:
- introduce a delayed root object into the filesystem, that use two lists to
  manage the delayed nodes which are created for every file/directory.
  One is used to manage all the delayed nodes that have delayed items. And the
  other is used to manage the delayed nodes which is waiting to be dealt with
  by the work thread.
- Every delayed node has two rb-tree, one is used to manage the directory name
  index which is going to be inserted into b+ tree, and the other is used to
  manage the directory name index which is going to be deleted from b+ tree.
- introduce a worker to deal with the delayed operation. This worker is used
  to deal with the works of the delayed directory name index items insertion
  and deletion and the delayed inode update.
  When the delayed items is beyond the lower limit, we create works for some
  delayed nodes and insert them into the work queue of the worker, and then
  go back.
  When the delayed items is beyond the upper bound, we create works for all
  the delayed nodes that haven't been dealt with, and insert them into the work
  queue of the worker, and then wait for that the untreated items is below some
  threshold value.
- When we want to insert a directory name index into b+ tree, we just add the
  information into the delayed inserting rb-tree.
  And then we check the number of the delayed items and do delayed items
  balance. (The balance policy is above.)
- When we want to delete a directory name index from the b+ tree, we search it
  in the inserting rb-tree at first. If we look it up, just drop it. If not,
  add the key of it into the delayed deleting rb-tree.
  Similar to the delayed inserting rb-tree, we also check the number of the
  delayed items and do delayed items balance.
  (The same to inserting manipulation)
- When we want to update the metadata of some inode, we cached the data of the
  inode into the delayed node. the worker will flush it into the b+ tree after
  dealing with the delayed insertion and deletion.
- We will move the delayed node to the tail of the list after we access the
  delayed node, By this way, we can cache more delayed items and merge more
  inode updates.
- If we want to commit transaction, we will deal with all the delayed node.
- the delayed node will be freed when we free the btrfs inode.
- Before we log the inode items, we commit all the directory name index items
  and the delayed inode update.

I did a quick test by the benchmark tool[1] and found we can improve the
performance of file creation by ~15%, and file deletion by ~20%.

Before applying this patch:
Create files:
        Total files: 50000
        Total time: 1.096108
        Average time: 0.000022
Delete files:
        Total files: 50000
        Total time: 1.510403
        Average time: 0.000030

After applying this patch:
Create files:
        Total files: 50000
        Total time: 0.932899
        Average time: 0.000019
Delete files:
        Total files: 50000
        Total time: 1.215732
        Average time: 0.000024

[1] http://marc.info/?l=linux-btrfs&m=128212635122920&q=p3

Many thanks for Kitayama-san's help!

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: David Sterba <dave@jikos.cz>
Tested-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Tested-by: Itaru Kitayama <kitayama@cl.bb4u.ne.jp>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-05-21 09:30:56 -04:00
..
acl.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2011-05-15 10:22:10 -07:00
async-thread.c Btrfs: don't walk around with task->state != TASK_RUNNING 2010-05-25 10:34:58 -04:00
async-thread.h Btrfs: fix deadlock on async thread startup 2009-10-05 09:44:45 -04:00
btrfs_inode.h btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
compat.h Btrfs: drop remaining LINUX_KERNEL_VERSION checks and compat code 2009-01-06 09:38:55 -05:00
compression.c Btrfs: check return value of btrfs_alloc_path() 2011-03-28 05:37:54 -04:00
compression.h btrfs: Extract duplicate decompress code 2010-12-22 23:15:50 +08:00
ctree.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
ctree.h btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
delayed-inode.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
delayed-inode.h btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
delayed-ref.c Btrfs: add initial tracepoint support for btrfs 2011-03-28 05:37:33 -04:00
delayed-ref.h Btrfs: Integrate metadata reservation with start_transaction 2010-05-25 10:34:50 -04:00
dir-item.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
disk-io.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
disk-io.h btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
export.c exportfs: Return the minimum required handle size 2011-03-14 09:15:28 -04:00
export.h NFS support for btrfs - v3 2008-09-25 11:04:06 -04:00
extent_io.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2011-04-26 08:26:58 -07:00
extent_io.h btrfs: using cached extent_state in set/unlock combinations 2011-04-11 20:45:36 -04:00
extent_map.c Fix common misspellings 2011-03-31 11:26:23 -03:00
extent_map.h btrfs: Allow to add new compression algorithm 2010-12-22 23:15:45 +08:00
extent-tree.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
file-item.c Btrfs: check return value of btrfs_alloc_path() 2011-03-28 05:37:54 -04:00
file.c Btrfs: deal with the case that we run out of space in the cache 2011-04-08 13:00:27 -04:00
free-space-cache.c Btrfs: free bitmaps properly when evicting the cache 2011-04-25 19:43:52 -04:00
free-space-cache.h Btrfs: add btrfs_trim_fs() to handle FITRIM 2011-03-28 05:37:47 -04:00
hash.h Btrfs: remove crc32c.h and use libcrc32c directly. 2009-06-10 11:29:53 -04:00
inode-item.c Btrfs: Integrate metadata reservation with start_transaction 2010-05-25 10:34:50 -04:00
inode-map.c Btrfs: cleanup some BUG_ON() 2011-03-28 05:37:35 -04:00
inode.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
ioctl.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
ioctl.h Merge branch 'lzo-support' of git://repo.or.cz/linux-btrfs-devel into btrfs-38 2011-01-16 11:25:54 -05:00
Kconfig btrfs: Add lzo compression support 2010-12-22 23:15:47 +08:00
locking.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
locking.h Btrfs: fix spinlock assertions on UP systems 2009-03-09 11:45:38 -04:00
lzo.c Btrfs: Avoid accessing unmapped kernel address 2011-02-16 15:37:58 -05:00
Makefile btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
ordered-data.c Btrfs: add initial tracepoint support for btrfs 2011-03-28 05:37:33 -04:00
ordered-data.h btrfs: Allow to add new compression algorithm 2010-12-22 23:15:45 +08:00
orphan.c Btrfs: fixup return code for btrfs_del_orphan_item 2010-12-09 13:57:15 -05:00
print-tree.c btrfs: fix missing break in switch phrase 2011-01-28 16:40:37 -05:00
print-tree.h
ref-cache.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
ref-cache.h Btrfs: use RB_ROOT to intialize rb_trees instead of setting rb_node to NULL 2010-03-08 16:26:50 -05:00
relocation.c Fix common misspellings 2011-03-31 11:26:23 -03:00
root-tree.c Btrfs: Fix uninitialized root flags for subvolumes 2011-04-05 01:20:24 -04:00
struct-funcs.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
super.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
sysfs.c Driver core: Constify struct sysfs_ops in struct kobj_type 2010-03-07 17:04:49 -08:00
transaction.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
transaction.h btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
tree-defrag.c Btrfs: cleanup warnings from gcc 4.6 (nonbugs) 2010-10-29 15:14:37 -04:00
tree-log.c btrfs: implement delayed inode items operation 2011-05-21 09:30:56 -04:00
tree-log.h Btrfs: Metadata ENOSPC handling for tree log 2010-05-25 10:34:53 -04:00
version.h Update Btrfs files for in-kernel usage 2008-09-25 15:41:59 -04:00
version.sh Btrfs: Fixes for 2.6.28-rc API changes 2008-11-19 21:17:22 -05:00
volumes.c Btrfs: do some plugging in the submit_bio threads 2011-04-19 20:12:40 -04:00
volumes.h Btrfs: make btrfs_map_block() return entire free extent for each device of RAID0/1/10/DUP 2011-03-28 05:37:45 -04:00
xattr.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2011-04-18 12:24:05 -07:00
xattr.h fs/vfs/security: pass last path component to LSM on inode creation 2011-02-01 11:12:29 -05:00
zlib.c zlib: slim down zlib_deflate() workspace when possible 2011-03-22 17:44:17 -07:00