include/linux/sched/prio.h

   1 #ifndef _SCHED_PRIO_H
   2 #define _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  */
  47 static 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  */
  55 static inline long rlimit_to_nice(long prio)
  56 {
  57         return (MAX_NICE - prio + 1);
  58 }
  59
  60 #endif /* _SCHED_PRIO_H */