Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1#ifndef IOPRIO_H
2#define IOPRIO_H
3
4#include <linux/sched.h>
5#include <linux/iocontext.h>
6
7/*
8 * Gives us 8 prio classes with 13-bits of data for each class
9 */
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 */
25enum {
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
37enum {
38 IOPRIO_WHO_PROCESS = 1,
39 IOPRIO_WHO_PGRP,
40 IOPRIO_WHO_USER,
41};
42
43/*
44 * Fallback BE priority
45 */
46#define IOPRIO_NORM (4)
47
48/*
49 * if process has set io priority explicitly, use that. if not, convert
50 * the cpu scheduler nice value to an io priority
51 */
52static inline int task_nice_ioprio(struct task_struct *task)
53{
54 return (task_nice(task) + 20) / 5;
55}
56
57/*
58 * This is for the case where the task hasn't asked for a specific IO class.
59 * Check for idle and rt task process, and return appropriate IO class.
60 */
61static inline int task_nice_ioclass(struct task_struct *task)
62{
63 if (task->policy == SCHED_IDLE)
64 return IOPRIO_CLASS_IDLE;
65 else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)
66 return IOPRIO_CLASS_RT;
67 else
68 return IOPRIO_CLASS_BE;
69}
70
71/*
72 * For inheritance, return the highest of the two given priorities
73 */
74extern int ioprio_best(unsigned short aprio, unsigned short bprio);
75
76extern int set_task_ioprio(struct task_struct *task, int ioprio);
77
78#endif