1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef IOPRIO_H
3 #define IOPRIO_H
4
5 #include <linux/sched.h>
6 #include <linux/iocontext.h>
7
8 /*
9 * Gives us 8 prio classes with 13-bits of data for each class
10 */
11 #define IOPRIO_CLASS_SHIFT (13)
12 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
13
14 #define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
15 #define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
16 #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
17
18 #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
19
20 /*
21 * These are the io priority groups as implemented by CFQ. RT is the realtime
22 * class, it always gets premium service. BE is the best-effort scheduling
23 * class, the default for any process. IDLE is the idle scheduling class, it
24 * is only served when no one else is using the disk.
25 */
26 enum {
27 IOPRIO_CLASS_NONE,
28 IOPRIO_CLASS_RT,
29 IOPRIO_CLASS_BE,
30 IOPRIO_CLASS_IDLE,
31 };
32
33 /*
34 * 8 best effort priority levels are supported
35 */
36 #define IOPRIO_BE_NR (8)
37
38 enum {
39 IOPRIO_WHO_PROCESS = 1,
40 IOPRIO_WHO_PGRP,
41 IOPRIO_WHO_USER,
42 };
43
44 /*
45 * Fallback BE priority
46 */
47 #define IOPRIO_NORM (4)
48
49 /*
50 * if process has set io priority explicitly, use that. if not, convert
51 * the cpu scheduler nice value to an io priority
52 */
task_nice_ioprio(struct task_struct * task)53 static inline int task_nice_ioprio(struct task_struct *task)
54 {
55 return (task_nice(task) + 20) / 5;
56 }
57
58 /*
59 * This is for the case where the task hasn't asked for a specific IO class.
60 * Check for idle and rt task process, and return appropriate IO class.
61 */
task_nice_ioclass(struct task_struct * task)62 static inline int task_nice_ioclass(struct task_struct *task)
63 {
64 if (task->policy == SCHED_IDLE)
65 return IOPRIO_CLASS_IDLE;
66 else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)
67 return IOPRIO_CLASS_RT;
68 else
69 return IOPRIO_CLASS_BE;
70 }
71
72 /*
73 * For inheritance, return the highest of the two given priorities
74 */
75 extern int ioprio_best(unsigned short aprio, unsigned short bprio);
76
77 extern int set_task_ioprio(struct task_struct *task, int ioprio);
78
79 #endif
80