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22e2c507 JA |
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 | ||
16 | #define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) | |
17 | ||
18 | /* | |
19 | * These are the io priority groups as implemented by CFQ. RT is the realtime | |
20 | * class, it always gets premium service. BE is the best-effort scheduling | |
21 | * class, the default for any process. IDLE is the idle scheduling class, it | |
22 | * is only served when no one else is using the disk. | |
23 | */ | |
24 | enum { | |
25 | IOPRIO_CLASS_NONE, | |
26 | IOPRIO_CLASS_RT, | |
27 | IOPRIO_CLASS_BE, | |
28 | IOPRIO_CLASS_IDLE, | |
29 | }; | |
30 | ||
31 | /* | |
32 | * 8 best effort priority levels are supported | |
33 | */ | |
34 | #define IOPRIO_BE_NR (8) | |
35 | ||
36 | asmlinkage int sys_ioprio_set(int, int, int); | |
37 | asmlinkage int sys_ioprio_get(int, int); | |
38 | ||
39 | enum { | |
40 | IOPRIO_WHO_PROCESS = 1, | |
41 | IOPRIO_WHO_PGRP, | |
42 | IOPRIO_WHO_USER, | |
43 | }; | |
44 | ||
45 | /* | |
46 | * if process has set io priority explicitly, use that. if not, convert | |
47 | * the cpu scheduler nice value to an io priority | |
48 | */ | |
49 | #define IOPRIO_NORM (4) | |
50 | static inline int task_ioprio(struct task_struct *task) | |
51 | { | |
52 | WARN_ON(!ioprio_valid(task->ioprio)); | |
53 | return IOPRIO_PRIO_DATA(task->ioprio); | |
54 | } | |
55 | ||
56 | static inline int task_nice_ioprio(struct task_struct *task) | |
57 | { | |
58 | return (task_nice(task) + 20) / 5; | |
59 | } | |
60 | ||
61 | /* | |
62 | * For inheritance, return the highest of the two given priorities | |
63 | */ | |
64 | static inline int ioprio_best(unsigned short aprio, unsigned short bprio) | |
65 | { | |
66 | unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); | |
67 | unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); | |
68 | ||
69 | if (!ioprio_valid(aprio)) | |
70 | return bprio; | |
71 | if (!ioprio_valid(bprio)) | |
72 | return aprio; | |
73 | ||
74 | if (aclass == IOPRIO_CLASS_NONE) | |
75 | aclass = IOPRIO_CLASS_BE; | |
76 | if (bclass == IOPRIO_CLASS_NONE) | |
77 | bclass = IOPRIO_CLASS_BE; | |
78 | ||
79 | if (aclass == bclass) | |
80 | return min(aprio, bprio); | |
81 | if (aclass > bclass) | |
82 | return bprio; | |
83 | else | |
84 | return aprio; | |
85 | } | |
86 | ||
87 | #endif |