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manager: fix GC algorithm
[people/ms/systemd.git] / ioprio.h
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1#ifndef IOPRIO_H
2#define IOPRIO_H
3
4/* This is minimal version of Linux' linux/ioprio.h header file, which
5 * is licensed GPL2 */
6
7#include <unistd.h>
8#include <sys/syscall.h>
9
10/*
11 * Gives us 8 prio classes with 13-bits of data for each class
12 */
13#define IOPRIO_BITS (16)
14#define IOPRIO_CLASS_SHIFT (13)
15#define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
16
17#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
18#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
19#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
20
21#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
22
23/*
24 * These are the io priority groups as implemented by CFQ. RT is the realtime
25 * class, it always gets premium service. BE is the best-effort scheduling
26 * class, the default for any process. IDLE is the idle scheduling class, it
27 * is only served when no one else is using the disk.
28 */
29enum {
30 IOPRIO_CLASS_NONE,
31 IOPRIO_CLASS_RT,
32 IOPRIO_CLASS_BE,
33 IOPRIO_CLASS_IDLE,
34};
35
36/*
37 * 8 best effort priority levels are supported
38 */
39#define IOPRIO_BE_NR (8)
40
41enum {
42 IOPRIO_WHO_PROCESS = 1,
43 IOPRIO_WHO_PGRP,
44 IOPRIO_WHO_USER,
45};
46
47static inline int ioprio_set(int which, int who, int ioprio)
48{
49 return syscall(__NR_ioprio_set, which, who, ioprio);
50}
51
52static inline int ioprio_get(int which, int who)
53{
54 return syscall(__NR_ioprio_get, which, who);
55}
56
57#endif