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_BITS (16)
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 */
26enum {
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
38enum {
39 IOPRIO_WHO_PROCESS = 1,
40 IOPRIO_WHO_PGRP,
41 IOPRIO_WHO_USER,
42};
43
44/*
45 * if process has set io priority explicitly, use that. if not, convert
46 * the cpu scheduler nice value to an io priority
47 */
48#define IOPRIO_NORM (4)
49static inline int task_ioprio(struct io_context *ioc)
50{
51 if (ioprio_valid(ioc->ioprio))
52 return IOPRIO_PRIO_DATA(ioc->ioprio);
53
54 return IOPRIO_NORM;
55}
56
57static inline int task_ioprio_class(struct io_context *ioc)
58{
59 if (ioprio_valid(ioc->ioprio))
60 return IOPRIO_PRIO_CLASS(ioc->ioprio);
61
62 return IOPRIO_CLASS_BE;
63}
64
65static inline int task_nice_ioprio(struct task_struct *task)
66{
67 return (task_nice(task) + 20) / 5;
68}
69
70/*
71 * This is for the case where the task hasn't asked for a specific IO class.
72 * Check for idle and rt task process, and return appropriate IO class.
73 */
74static inline int task_nice_ioclass(struct task_struct *task)
75{
76 if (task->policy == SCHED_IDLE)
77 return IOPRIO_CLASS_IDLE;
78 else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)
79 return IOPRIO_CLASS_RT;
80 else
81 return IOPRIO_CLASS_BE;
82}
83
84/*
85 * For inheritance, return the highest of the two given priorities
86 */
87extern int ioprio_best(unsigned short aprio, unsigned short bprio);
88
89extern int set_task_ioprio(struct task_struct *task, int ioprio);
90
91#endif