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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) | |
3b18152c | 15 | #define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) |
22e2c507 JA |
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 | */ | |
25 | enum { | |
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 | ||
22e2c507 JA |
37 | enum { |
38 | IOPRIO_WHO_PROCESS = 1, | |
39 | IOPRIO_WHO_PGRP, | |
40 | IOPRIO_WHO_USER, | |
41 | }; | |
42 | ||
43 | /* | |
44 | * if process has set io priority explicitly, use that. if not, convert | |
45 | * the cpu scheduler nice value to an io priority | |
46 | */ | |
47 | #define IOPRIO_NORM (4) | |
48 | static inline int task_ioprio(struct task_struct *task) | |
49 | { | |
50 | WARN_ON(!ioprio_valid(task->ioprio)); | |
51 | return IOPRIO_PRIO_DATA(task->ioprio); | |
52 | } | |
53 | ||
54 | static inline int task_nice_ioprio(struct task_struct *task) | |
55 | { | |
56 | return (task_nice(task) + 20) / 5; | |
57 | } | |
58 | ||
59 | /* | |
60 | * For inheritance, return the highest of the two given priorities | |
61 | */ | |
62 | static inline int ioprio_best(unsigned short aprio, unsigned short bprio) | |
63 | { | |
64 | unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); | |
65 | unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); | |
66 | ||
67 | if (!ioprio_valid(aprio)) | |
68 | return bprio; | |
69 | if (!ioprio_valid(bprio)) | |
70 | return aprio; | |
71 | ||
72 | if (aclass == IOPRIO_CLASS_NONE) | |
73 | aclass = IOPRIO_CLASS_BE; | |
74 | if (bclass == IOPRIO_CLASS_NONE) | |
75 | bclass = IOPRIO_CLASS_BE; | |
76 | ||
77 | if (aclass == bclass) | |
78 | return min(aprio, bprio); | |
79 | if (aclass > bclass) | |
80 | return bprio; | |
81 | else | |
82 | return aprio; | |
83 | } | |
84 | ||
85 | #endif |