1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCHED_PRIO_H
3 #define _LINUX_SCHED_PRIO_H
4
5 #define MAX_NICE 19
6 #define MIN_NICE -20
7 #define NICE_WIDTH (MAX_NICE - MIN_NICE + 1)
8
9 /*
10 * Priority of a process goes from 0..MAX_PRIO-1, valid RT
11 * priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH
12 * tasks are in the range MAX_RT_PRIO..MAX_PRIO-1. Priority
13 * values are inverted: lower p->prio value means higher priority.
14 *
15 * The MAX_USER_RT_PRIO value allows the actual maximum
16 * RT priority to be separate from the value exported to
17 * user-space. This allows kernel threads to set their
18 * priority to a value higher than any user task. Note:
19 * MAX_RT_PRIO must not be smaller than MAX_USER_RT_PRIO.
20 */
21
22 #define MAX_USER_RT_PRIO 100
23 #define MAX_RT_PRIO MAX_USER_RT_PRIO
24
25 #define MAX_PRIO (MAX_RT_PRIO + NICE_WIDTH)
26 #define DEFAULT_PRIO (MAX_RT_PRIO + NICE_WIDTH / 2)
27
28 /*
29 * Convert user-nice values [ -20 ... 0 ... 19 ]
30 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
31 * and back.
32 */
33 #define NICE_TO_PRIO(nice) ((nice) + DEFAULT_PRIO)
34 #define PRIO_TO_NICE(prio) ((prio) - DEFAULT_PRIO)
35
36 /*
37 * 'User priority' is the nice value converted to something we
38 * can work with better when scaling various scheduler parameters,
39 * it's a [ 0 ... 39 ] range.
40 */
41 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
42 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
43 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
44
45 /*
46 * Convert nice value [19,-20] to rlimit style value [1,40].
47 */
48 static inline long nice_to_rlimit(long nice)
49 {
50 return (MAX_NICE - nice + 1);
51 }
52
53 /*
54 * Convert rlimit style value [1,40] to nice value [-20, 19].
55 */
56 static inline long rlimit_to_nice(long prio)
57 {
58 return (MAX_NICE - prio + 1);
59 }
60
61 #endif /* _LINUX_SCHED_PRIO_H */