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

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