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ext4: pass context information to jbd2__journal_start()

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So we can better understand what bits of ext4 are responsible for
long-running jbd2 handles, use jbd2__journal_start() so we can pass
context information for logging purposes.

The recommended way for finding the longer-running handles is:

   T=/sys/kernel/debug/tracing
   EVENT=$T/events/jbd2/jbd2_handle_stats
   echo "interval > 5" > $EVENT/filter
   echo 1 > $EVENT/enable

   ./run-my-fs-benchmark

   cat $T/trace > /tmp/problem-handles

This will list handles that were active for longer than 20ms.  Having
longer-running handles is bad, because a commit started at the wrong
time could stall for those 20+ milliseconds, which could delay an
fsync() or an O_SYNC operation.  Here is an example line from the
trace file describing a handle which lived on for 311 jiffies, or over
1.2 seconds:

postmark-2917  [000] ....   196.435786: jbd2_handle_stats: dev 254,32 
   tid 570 type 2 line_no 2541 interval 311 sync 0 requested_blocks 1
   dirtied_blocks 0

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
2013-02-08 21:59:22 -05:00
parent 722887ddc8
commit 9924a92a8c
16 changed files with 111 additions and 69 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fs/ext4/ext4_jbd2.h
+28 -3
View File
@@ -110,6 +110,22 @@
#define EXT4_MAXQUOTAS_INIT_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_INIT_BLOCKS(sb))
#define EXT4_MAXQUOTAS_DEL_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_DEL_BLOCKS(sb))
/*
* Ext4 handle operation types -- for logging purposes
*/
#define EXT4_HT_MISC 0
#define EXT4_HT_INODE 1
#define EXT4_HT_WRITE_PAGE 2
#define EXT4_HT_MAP_BLOCKS 3
#define EXT4_HT_DIR 4
#define EXT4_HT_TRUNCATE 5
#define EXT4_HT_QUOTA 6
#define EXT4_HT_RESIZE 7
#define EXT4_HT_MIGRATE 8
#define EXT4_HT_MOVE_EXTENTS 9
#define EXT4_HT_XATTR 10
#define EXT4_HT_MAX 11
/**
* struct ext4_journal_cb_entry - Base structure for callback information.
*
@@ -234,7 +250,8 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
#define ext4_handle_dirty_super(handle, sb) \
__ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))
handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line,
int type, int nblocks);
int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle);
#define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)
@@ -268,9 +285,17 @@ static inline int ext4_handle_has_enough_credits(handle_t *handle, int needed)
return 1;
}
static inline handle_t *ext4_journal_start(struct inode *inode, int nblocks)
#define ext4_journal_start_sb(sb, type, nblocks) \
__ext4_journal_start_sb((sb), __LINE__, (type), (nblocks))
#define ext4_journal_start(inode, type, nblocks) \
__ext4_journal_start((inode), __LINE__, (type), (nblocks))
static inline handle_t *__ext4_journal_start(struct inode *inode,
unsigned int line, int type,
int nblocks)
{
return ext4_journal_start_sb(inode->i_sb, nblocks);
return __ext4_journal_start_sb(inode->i_sb, line, type, nblocks);
}
#define ext4_journal_stop(handle) \