Line data Source code
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 : */
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 : * 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)
49 : static 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 :
57 : static 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 :
65 : static 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 : */
74 : static 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 : */
87 : extern int ioprio_best(unsigned short aprio, unsigned short bprio);
88 :
89 : extern int set_task_ioprio(struct task_struct *task, int ioprio);
90 1 :
91 : #endif
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