writeback: trace event writeback_single_inode

It is valuable to know how the dirty inodes are iterated and their IO size.

"writeback_single_inode: bdi 8:0: ino=134246746 state=I_DIRTY_SYNC|I_SYNC age=414 index=0 to_write=1024 wrote=0"

- "state" reflects inode->i_state at the end of writeback_single_inode()
- "index" reflects mapping->writeback_index after the ->writepages() call
- "to_write" is the wbc->nr_to_write at entrance of writeback_single_inode()
- "wrote" is the number of pages actually written

v2: add trace event writeback_single_inode_requeue as proposed by Dave.

CC: Dave Chinner <david@fromorbit.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index b2cfac5f3313..898277bc89b4 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -8,6 +8,19 @@
 #include <linux/device.h>
 #include <linux/writeback.h>
 
+#define show_inode_state(state)                                 \
+        __print_flags(state, "|",                               \
+                {I_DIRTY_SYNC,          "I_DIRTY_SYNC"},        \
+                {I_DIRTY_DATASYNC,      "I_DIRTY_DATASYNC"},    \
+                {I_DIRTY_PAGES,         "I_DIRTY_PAGES"},       \
+                {I_NEW,                 "I_NEW"},               \
+                {I_WILL_FREE,           "I_WILL_FREE"},         \
+                {I_FREEING,             "I_FREEING"},           \
+                {I_CLEAR,               "I_CLEAR"},             \
+                {I_SYNC,                "I_SYNC"},              \
+                {I_REFERENCED,          "I_REFERENCED"}         \
+        )
+
 struct wb_writeback_work;
 
 DECLARE_EVENT_CLASS(writeback_work_class,
@@ -184,6 +197,63 @@ DEFINE_EVENT(writeback_congest_waited_template, writeback_wait_iff_congested,
         TP_ARGS(usec_timeout, usec_delayed)
 );
 
+DECLARE_EVENT_CLASS(writeback_single_inode_template,
+
+        TP_PROTO(struct inode *inode,
+                 struct writeback_control *wbc,
+                 unsigned long nr_to_write
+        ),
+
+        TP_ARGS(inode, wbc, nr_to_write),
+
+        TP_STRUCT__entry(
+                __array(char, name, 32)
+                __field(unsigned long, ino)
+                __field(unsigned long, state)
+                __field(unsigned long, age)
+                __field(unsigned long, writeback_index)
+                __field(long, nr_to_write)
+                __field(unsigned long, wrote)
+        ),
+
+        TP_fast_assign(
+                strncpy(__entry->name,
+                        dev_name(inode->i_mapping->backing_dev_info->dev), 32);
+                __entry->ino            = inode->i_ino;
+                __entry->state          = inode->i_state;
+                __entry->age            = (jiffies - inode->dirtied_when) *
+                                                                1000 / HZ;
+                __entry->writeback_index = inode->i_mapping->writeback_index;
+                __entry->nr_to_write    = nr_to_write;
+                __entry->wrote          = nr_to_write - wbc->nr_to_write;
+        ),
+
+        TP_printk("bdi %s: ino=%lu state=%s age=%lu "
+                  "index=%lu to_write=%ld wrote=%lu",
+                  __entry->name,
+                  __entry->ino,
+                  show_inode_state(__entry->state),
+                  __entry->age,
+                  __entry->writeback_index,
+                  __entry->nr_to_write,
+                  __entry->wrote
+        )
+);
+
+DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode_requeue,
+        TP_PROTO(struct inode *inode,
+                 struct writeback_control *wbc,
+                 unsigned long nr_to_write),
+        TP_ARGS(inode, wbc, nr_to_write)
+);
+
+DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode,
+        TP_PROTO(struct inode *inode,
+                 struct writeback_control *wbc,
+                 unsigned long nr_to_write),
+        TP_ARGS(inode, wbc, nr_to_write)
+);
+
 #endif /* _TRACE_WRITEBACK_H */
 
 /* This part must be outside protection */