1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * task_io_accounting: a structure which is us 3 * task_io_accounting: a structure which is used for recording a single task's
4 * IO statistics. 4 * IO statistics.
5 * 5 *
6 * Don't include this header file directly - i 6 * Don't include this header file directly - it is designed to be dragged in via
7 * sched.h. 7 * sched.h.
8 * 8 *
9 * Blame Andrew Morton for all this. 9 * Blame Andrew Morton for all this.
10 */ 10 */
11 11
12 struct task_io_accounting { 12 struct task_io_accounting {
13 #ifdef CONFIG_TASK_XACCT 13 #ifdef CONFIG_TASK_XACCT
14 /* bytes read */ 14 /* bytes read */
15 u64 rchar; 15 u64 rchar;
16 /* bytes written */ 16 /* bytes written */
17 u64 wchar; 17 u64 wchar;
18 /* # of read syscalls */ 18 /* # of read syscalls */
19 u64 syscr; 19 u64 syscr;
20 /* # of write syscalls */ 20 /* # of write syscalls */
21 u64 syscw; 21 u64 syscw;
22 #endif /* CONFIG_TASK_XACCT */ 22 #endif /* CONFIG_TASK_XACCT */
23 23
24 #ifdef CONFIG_TASK_IO_ACCOUNTING 24 #ifdef CONFIG_TASK_IO_ACCOUNTING
25 /* 25 /*
26 * The number of bytes which this task 26 * The number of bytes which this task has caused to be read from
27 * storage. 27 * storage.
28 */ 28 */
29 u64 read_bytes; 29 u64 read_bytes;
30 30
31 /* 31 /*
32 * The number of bytes which this task 32 * The number of bytes which this task has caused, or shall cause to be
33 * written to disk. 33 * written to disk.
34 */ 34 */
35 u64 write_bytes; 35 u64 write_bytes;
36 36
37 /* 37 /*
38 * A task can cause "negative" IO too. 38 * A task can cause "negative" IO too. If this task truncates some
39 * dirty pagecache, some IO which anot 39 * dirty pagecache, some IO which another task has been accounted for
40 * (in its write_bytes) will not be ha 40 * (in its write_bytes) will not be happening. We _could_ just
41 * subtract that from the truncating t 41 * subtract that from the truncating task's write_bytes, but there is
42 * information loss in doing that. 42 * information loss in doing that.
43 */ 43 */
44 u64 cancelled_write_bytes; 44 u64 cancelled_write_bytes;
45 #endif /* CONFIG_TASK_IO_ACCOUNTING */ 45 #endif /* CONFIG_TASK_IO_ACCOUNTING */
46 }; 46 };
47 47
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