LXR linux/include/linux/sched/prio.h

   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 */
  48static 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 */
  56static inline long rlimit_to_nice(long prio)
  57{
  58        return (MAX_NICE - prio + 1);
  59}
  60
  61#endif /* _LINUX_SCHED_PRIO_H */
  62