1 #ifndef IOPRIO_H
2 #define IOPRIO_H
3
4 #include <linux/sched.h>
5
6 /*
7 * Gives us 8 prio classes with 13-bits of data for each class
8 */
9 #define IOPRIO_BITS (16)
10 #define IOPRIO_CLASS_SHIFT (13)
11 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
12
13 #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
14 #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
15 #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
16
17 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
18
19 /*
20 * These are the io priority groups as implemented by CFQ. RT is the realtime
21 * class, it always gets premium service. BE is the best-effort scheduling
22 * class, the default for any process. IDLE is the idle scheduling class, it
23 * is only served when no one else is using the disk.
24 */
25 enum {
26 IOPRIO_CLASS_NONE,
27 IOPRIO_CLASS_RT,
28 IOPRIO_CLASS_BE,
29 IOPRIO_CLASS_IDLE,
30 };
31
32 /*
33 * 8 best effort priority levels are supported
34 */
35 #define IOPRIO_BE_NR (8)
36
37 enum {
38 IOPRIO_WHO_PROCESS = 1,
39 IOPRIO_WHO_PGRP,
40 IOPRIO_WHO_USER,
41 };
42
43 /*
44 * if process has set io priority explicitly, use that. if not, convert
45 * the cpu scheduler nice value to an io priority
46 */
47 #define IOPRIO_NORM (4)
task_ioprio(struct task_struct * task)48 static inline int task_ioprio(struct task_struct *task)
49 {
50 WARN_ON(!ioprio_valid(task->ioprio));
51 return IOPRIO_PRIO_DATA(task->ioprio);
52 }
53
task_nice_ioprio(struct task_struct * task)54 static inline int task_nice_ioprio(struct task_struct *task)
55 {
56 return (task_nice(task) + 20) / 5;
57 }
58
59 /*
60 * For inheritance, return the highest of the two given priorities
61 */
62 extern int ioprio_best(unsigned short aprio, unsigned short bprio);
63
64 #endif
65