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Commit 251d6a47 authored by Wu Fengguang's avatar Wu Fengguang
Browse files

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: default avatarWu Fengguang <fengguang.wu@intel.com>
parent 846d5a09

fs/fs-writeback.c

+4 −0
Original line number Diff line number Diff line
@@ -346,6 +346,7 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 
		       struct writeback_control *wbc)

{

	struct address_space *mapping = inode->i_mapping;

	long nr_to_write = wbc->nr_to_write;

	unsigned dirty;

	int ret;
@@ -368,6 +369,8 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 
		 */

		if (wbc->sync_mode != WB_SYNC_ALL) {

			requeue_io(inode, wb);

			trace_writeback_single_inode_requeue(inode, wbc,

							     nr_to_write);

			return 0;

		}
@@ -467,6 +470,7 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 
		}

	}

	inode_sync_complete(inode);

	trace_writeback_single_inode(inode, wbc, nr_to_write);

	return ret;

}

include/trace/events/writeback.h

+70 −0
Original line number Diff line number Diff line
@@ -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 */