nilfs2: add a tracepoint for transaction events

This patch adds a tracepoint for transaction events of nilfs.  With the
tracepoint, these events can be tracked: begin, abort, commit, trylock,
lock, and unlock.  Basically, these events have corresponding functions
e.g.  begin event corresponds nilfs_transaction_begin().  The unlock event
is an exception.  It corresponds to the iteration in
nilfs_transaction_lock().

Only one tracepoint is introcued: nilfs2_transaction_transition.  The
above events are distinguished with newly introduced enum.  With this
tracepoint, we can analyse a critical section of segment constructoin.

Sample output by tpoint of perf-tools:
              cp-4457  [000] ...1    63.266220: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 1 flags = 9 state = BEGIN
              cp-4457  [000] ...1    63.266221: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 0 flags = 9 state = COMMIT
              cp-4457  [000] ...1    63.266221: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 0 flags = 9 state = COMMIT
        segctord-4371  [001] ...1    68.261196: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = TRYLOCK
        segctord-4371  [001] ...1    68.261280: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = LOCK
        segctord-4371  [001] ...1    68.261877: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 1 flags = 10 state = BEGIN
        segctord-4371  [001] ...1    68.262116: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 18 state = COMMIT
        segctord-4371  [001] ...1    68.265032: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 18 state = UNLOCK
        segctord-4371  [001] ...1   132.376847: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = TRYLOCK

This patch also does trivial cleaning of comma usage in collection stage
transition event for consistent coding style.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index ef35404..3fc4732 100644 (file)
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -214,11 +214,18 @@ int nilfs_transaction_begin(struct super_block *sb,
 {
        struct the_nilfs *nilfs;
        int ret = nilfs_prepare_segment_lock(ti);
+       struct nilfs_transaction_info *trace_ti;
 
        if (unlikely(ret < 0))
                return ret;
-       if (ret > 0)
+       if (ret > 0) {
+               trace_ti = current->journal_info;
+
+               trace_nilfs2_transaction_transition(sb, trace_ti,
+                                   trace_ti->ti_count, trace_ti->ti_flags,
+                                   TRACE_NILFS2_TRANSACTION_BEGIN);
                return 0;
+       }
 
        sb_start_intwrite(sb);
 
@@ -229,6 +236,11 @@ int nilfs_transaction_begin(struct super_block *sb,
                ret = -ENOSPC;
                goto failed;
        }
+
+       trace_ti = current->journal_info;
+       trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
+                                           trace_ti->ti_flags,
+                                           TRACE_NILFS2_TRANSACTION_BEGIN);
        return 0;
 
  failed:
@@ -261,6 +273,8 @@ int nilfs_transaction_commit(struct super_block *sb)
        ti->ti_flags |= NILFS_TI_COMMIT;
        if (ti->ti_count > 0) {
                ti->ti_count--;
+               trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                           ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
                return 0;
        }
        if (nilfs->ns_writer) {
@@ -272,6 +286,9 @@ int nilfs_transaction_commit(struct super_block *sb)
                        nilfs_segctor_do_flush(sci, 0);
        }
        up_read(&nilfs->ns_segctor_sem);
+       trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                           ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
+
        current->journal_info = ti->ti_save;
 
        if (ti->ti_flags & NILFS_TI_SYNC)
@@ -290,10 +307,15 @@ void nilfs_transaction_abort(struct super_block *sb)
        BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
        if (ti->ti_count > 0) {
                ti->ti_count--;
+               trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                           ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
                return;
        }
        up_read(&nilfs->ns_segctor_sem);
 
+       trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                   ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
+
        current->journal_info = ti->ti_save;
        if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
                kmem_cache_free(nilfs_transaction_cachep, ti);
@@ -339,6 +361,9 @@ static void nilfs_transaction_lock(struct super_block *sb,
        current->journal_info = ti;
 
        for (;;) {
+               trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                           ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
+
                down_write(&nilfs->ns_segctor_sem);
                if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
                        break;
@@ -350,6 +375,9 @@ static void nilfs_transaction_lock(struct super_block *sb,
        }
        if (gcflag)
                ti->ti_flags |= NILFS_TI_GC;
+
+       trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                           ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
 }
 
 static void nilfs_transaction_unlock(struct super_block *sb)
@@ -362,6 +390,9 @@ static void nilfs_transaction_unlock(struct super_block *sb)
 
        up_write(&nilfs->ns_segctor_sem);
        current->journal_info = ti->ti_save;
+
+       trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
+                           ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
 }
 
 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,

diff --git a/include/trace/events/nilfs2.h b/include/trace/events/nilfs2.h
index 573da00..e5649ac 100644 (file)
--- a/include/trace/events/nilfs2.h
+++ b/include/trace/events/nilfs2.h
@@ -42,6 +42,59 @@ TRACE_EVENT(nilfs2_collection_stage_transition,
                      show_collection_stage(__entry->stage))
 );
 
+#ifndef TRACE_HEADER_MULTI_READ
+enum nilfs2_transaction_transition_state {
+       TRACE_NILFS2_TRANSACTION_BEGIN,
+       TRACE_NILFS2_TRANSACTION_COMMIT,
+       TRACE_NILFS2_TRANSACTION_ABORT,
+       TRACE_NILFS2_TRANSACTION_TRYLOCK,
+       TRACE_NILFS2_TRANSACTION_LOCK,
+       TRACE_NILFS2_TRANSACTION_UNLOCK,
+};
+#endif
+
+#define show_transaction_state(type)                                   \
+       __print_symbolic(type,                                          \
+                        { TRACE_NILFS2_TRANSACTION_BEGIN, "BEGIN" },   \
+                        { TRACE_NILFS2_TRANSACTION_COMMIT, "COMMIT" }, \
+                        { TRACE_NILFS2_TRANSACTION_ABORT, "ABORT" },   \
+                        { TRACE_NILFS2_TRANSACTION_TRYLOCK, "TRYLOCK" }, \
+                        { TRACE_NILFS2_TRANSACTION_LOCK, "LOCK" },     \
+                        { TRACE_NILFS2_TRANSACTION_UNLOCK, "UNLOCK" })
+
+TRACE_EVENT(nilfs2_transaction_transition,
+           TP_PROTO(struct super_block *sb,
+                    struct nilfs_transaction_info *ti,
+                    int count,
+                    unsigned int flags,
+                    enum nilfs2_transaction_transition_state state),
+
+           TP_ARGS(sb, ti, count, flags, state),
+
+           TP_STRUCT__entry(
+                   __field(void *, sb)
+                   __field(void *, ti)
+                   __field(int, count)
+                   __field(unsigned int, flags)
+                   __field(int, state)
+           ),
+
+           TP_fast_assign(
+                   __entry->sb = sb;
+                   __entry->ti = ti;
+                   __entry->count = count;
+                   __entry->flags = flags;
+                   __entry->state = state;
+                   ),
+
+           TP_printk("sb = %p ti = %p count = %d flags = %x state = %s",
+                     __entry->sb,
+                     __entry->ti,
+                     __entry->count,
+                     __entry->flags,
+                     show_transaction_state(__entry->state))
+);
+
 #endif /* _TRACE_NILFS2_H */
 
 /* This part must be outside protection */