e30b5dca15
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 <lkp@linux.intel.com>
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
127 lines
3.4 KiB
C
127 lines
3.4 KiB
C
/*
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* fs/ext4/extents_status.h
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*
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* Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
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* Modified by
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* Allison Henderson <achender@linux.vnet.ibm.com>
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* Zheng Liu <wenqing.lz@taobao.com>
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*
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*/
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#ifndef _EXT4_EXTENTS_STATUS_H
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#define _EXT4_EXTENTS_STATUS_H
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/*
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* Turn on ES_DEBUG__ to get lots of info about extent status operations.
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*/
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#ifdef ES_DEBUG__
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#define es_debug(fmt, ...) printk(fmt, ##__VA_ARGS__)
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#else
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#define es_debug(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
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#endif
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/*
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* With ES_AGGRESSIVE_TEST defined, the result of es caching will be
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* checked with old map_block's result.
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*/
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#define ES_AGGRESSIVE_TEST__
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/*
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* These flags live in the high bits of extent_status.es_pblk
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*/
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#define EXTENT_STATUS_WRITTEN (1ULL << 63)
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#define EXTENT_STATUS_UNWRITTEN (1ULL << 62)
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#define EXTENT_STATUS_DELAYED (1ULL << 61)
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#define EXTENT_STATUS_HOLE (1ULL << 60)
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#define EXTENT_STATUS_FLAGS (EXTENT_STATUS_WRITTEN | \
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EXTENT_STATUS_UNWRITTEN | \
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EXTENT_STATUS_DELAYED | \
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EXTENT_STATUS_HOLE)
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struct ext4_extent;
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struct extent_status {
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struct rb_node rb_node;
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ext4_lblk_t es_lblk; /* first logical block extent covers */
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ext4_lblk_t es_len; /* length of extent in block */
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ext4_fsblk_t es_pblk; /* first physical block */
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};
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struct ext4_es_tree {
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struct rb_root root;
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struct extent_status *cache_es; /* recently accessed extent */
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};
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extern int __init ext4_init_es(void);
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extern void ext4_exit_es(void);
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extern void ext4_es_init_tree(struct ext4_es_tree *tree);
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extern int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
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ext4_lblk_t len, ext4_fsblk_t pblk,
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unsigned long long status);
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extern int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
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ext4_lblk_t len);
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extern void ext4_es_find_delayed_extent_range(struct inode *inode,
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ext4_lblk_t lblk, ext4_lblk_t end,
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struct extent_status *es);
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extern int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
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struct extent_status *es);
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extern int ext4_es_zeroout(struct inode *inode, struct ext4_extent *ex);
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static inline int ext4_es_is_written(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_WRITTEN) != 0;
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}
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static inline int ext4_es_is_unwritten(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_UNWRITTEN) != 0;
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}
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static inline int ext4_es_is_delayed(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_DELAYED) != 0;
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}
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static inline int ext4_es_is_hole(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_HOLE) != 0;
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}
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static inline ext4_fsblk_t ext4_es_status(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_FLAGS);
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}
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static inline ext4_fsblk_t ext4_es_pblock(struct extent_status *es)
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{
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return (es->es_pblk & ~EXTENT_STATUS_FLAGS);
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}
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static inline void ext4_es_store_pblock(struct extent_status *es,
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ext4_fsblk_t pb)
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{
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ext4_fsblk_t block;
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block = (pb & ~EXTENT_STATUS_FLAGS) |
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(es->es_pblk & EXTENT_STATUS_FLAGS);
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es->es_pblk = block;
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}
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static inline void ext4_es_store_status(struct extent_status *es,
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unsigned long long status)
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{
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ext4_fsblk_t block;
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block = (status & EXTENT_STATUS_FLAGS) |
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(es->es_pblk & ~EXTENT_STATUS_FLAGS);
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es->es_pblk = block;
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}
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extern void ext4_es_register_shrinker(struct super_block *sb);
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extern void ext4_es_unregister_shrinker(struct super_block *sb);
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extern void ext4_es_lru_add(struct inode *inode);
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extern void ext4_es_lru_del(struct inode *inode);
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#endif /* _EXT4_EXTENTS_STATUS_H */
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