[linux-2.6-block.git] / include / linux / task_io_accounting.h

/*
 * task_io_accounting: a structure which is used for recording a single task's
 * IO statistics.
 *
 * Don't include this header file directly - it is designed to be dragged in via
 * sched.h.
 *
 * Blame akpm@osdl.org for all this.
 */

#ifdef CONFIG_TASK_IO_ACCOUNTING
struct task_io_accounting {
	/*
	 * The number of bytes which this task has caused to be read from
	 * storage.
	 */
	u64 read_bytes;

	/*
	 * The number of bytes which this task has caused, or shall cause to be
	 * written to disk.
	 */
	u64 write_bytes;

	/*
	 * A task can cause "negative" IO too.  If this task truncates some
	 * dirty pagecache, some IO which another task has been accounted for
	 * (in its write_bytes) will not be happening.  We _could_ just
	 * subtract that from the truncating task's write_bytes, but there is
	 * information loss in doing that.
	 */
	u64 cancelled_write_bytes;
};
#else
struct task_io_accounting {
};
#endif
Commit	Line	Data
7c3ab738 AM	1	/*
	2	* task_io_accounting: a structure which is used for recording a single task's
	3	* IO statistics.
	4	*
	5	* Don't include this header file directly - it is designed to be dragged in via
	6	* sched.h.
	7	*
	8	* Blame akpm@osdl.org for all this.
	9	*/
	10
	11	#ifdef CONFIG_TASK_IO_ACCOUNTING
	12	struct task_io_accounting {
	13	/*
	14	* The number of bytes which this task has caused to be read from
	15	* storage.
	16	*/
	17	u64 read_bytes;
	18
	19	/*
	20	* The number of bytes which this task has caused, or shall cause to be
	21	* written to disk.
	22	*/
	23	u64 write_bytes;
	24
	25	/*
	26	* A task can cause "negative" IO too. If this task truncates some
	27	* dirty pagecache, some IO which another task has been accounted for
	28	* (in its write_bytes) will not be happening. We _could_ just
	29	* subtract that from the truncating task's write_bytes, but there is
	30	* information loss in doing that.
	31	*/
	32	u64 cancelled_write_bytes;
	33	};
	34	#else
	35	struct task_io_accounting {
	36	};
	37	#endif