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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 | |
91 | #endif |
92 |
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