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btrfs: extent-tree: Add trace events for space info numbers update

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Add trace event for update_bytes_pinned() and update_bytes_may_use() to
detect underflow better.

The output would be something like (only showing data part):

  ## Buffered write start, 16K total ##
  2255.954 xfs_io/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=4096
  2257.169 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=4096 diff=4096
  2257.346 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=8192 diff=4096
  2257.542 sudo/860 btrfs:update_bytes_may_use:(nil)U: type=DATA old=12288 diff=4096

  ## Delalloc start ##
  3727.853 kworker/u8:3-e/700 btrfs:update_bytes_may_use:(nil)U: type=DATA old=16384 diff=-16384

  ## Space cache update ##
  3733.132 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=65536
  3733.169 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=65536 diff=-65536
  3739.868 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=0 diff=65536
  3739.891 sudo/862 btrfs:update_bytes_may_use:(nil)U: type=DATA old=65536 diff=-65536

These two trace events will allow bcc tool to probe btrfs_space_info
changes and detect underflow with more details (e.g. backtrace for each
update).

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo
2019-04-29 14:03:33 +08:00
committed by David Sterba
parent 0185f364cb
commit 480b9b4d84
2 changed files with 60 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
include/trace/events/btrfs.h
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@@ -29,6 +29,7 @@ struct btrfs_qgroup_extent_record;
struct btrfs_qgroup;
struct extent_io_tree;
struct prelim_ref;
struct btrfs_space_info;
TRACE_DEFINE_ENUM(FLUSH_DELAYED_ITEMS_NR);
TRACE_DEFINE_ENUM(FLUSH_DELAYED_ITEMS);
@@ -2091,6 +2092,45 @@ DEFINE_BTRFS_LOCK_EVENT(btrfs_try_tree_read_lock);
DEFINE_BTRFS_LOCK_EVENT(btrfs_try_tree_write_lock);
DEFINE_BTRFS_LOCK_EVENT(btrfs_tree_read_lock_atomic);
DECLARE_EVENT_CLASS(btrfs__space_info_update,
TP_PROTO(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *sinfo, u64 old, s64 diff),
TP_ARGS(fs_info, sinfo, old, diff),
TP_STRUCT__entry_btrfs(
__field( u64, type )
__field( u64, old )
__field( s64, diff )
),
TP_fast_assign_btrfs(fs_info,
__entry->type = sinfo->flags;
__entry->old = old;
__entry->diff = diff;
),
TP_printk_btrfs("type=%s old=%llu diff=%lld",
__print_flags(__entry->type, "|", BTRFS_GROUP_FLAGS),
__entry->old, __entry->diff)
);
DEFINE_EVENT(btrfs__space_info_update, update_bytes_may_use,
TP_PROTO(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *sinfo, u64 old, s64 diff),
TP_ARGS(fs_info, sinfo, old, diff)
);
DEFINE_EVENT(btrfs__space_info_update, update_bytes_pinned,
TP_PROTO(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *sinfo, u64 old, s64 diff),
TP_ARGS(fs_info, sinfo, old, diff)
);
#endif /* _TRACE_BTRFS_H */
/* This part must be outside protection */