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kernel/linux-rt-4.4.41/include/linux/sched/prio.h 1.66 KB
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  #ifndef _SCHED_PRIO_H
  #define _SCHED_PRIO_H
  
  #define MAX_NICE	19
  #define MIN_NICE	-20
  #define NICE_WIDTH	(MAX_NICE - MIN_NICE + 1)
  
  /*
   * Priority of a process goes from 0..MAX_PRIO-1, valid RT
   * priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH
   * tasks are in the range MAX_RT_PRIO..MAX_PRIO-1. Priority
   * values are inverted: lower p->prio value means higher priority.
   *
   * The MAX_USER_RT_PRIO value allows the actual maximum
   * RT priority to be separate from the value exported to
   * user-space.  This allows kernel threads to set their
   * priority to a value higher than any user task. Note:
   * MAX_RT_PRIO must not be smaller than MAX_USER_RT_PRIO.
   */
  
  #define MAX_USER_RT_PRIO	100
  #define MAX_RT_PRIO		MAX_USER_RT_PRIO
  
  #define MAX_PRIO		(MAX_RT_PRIO + NICE_WIDTH)
  #define DEFAULT_PRIO		(MAX_RT_PRIO + NICE_WIDTH / 2)
  
  /*
   * Convert user-nice values [ -20 ... 0 ... 19 ]
   * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
   * and back.
   */
  #define NICE_TO_PRIO(nice)	((nice) + DEFAULT_PRIO)
  #define PRIO_TO_NICE(prio)	((prio) - DEFAULT_PRIO)
  
  /*
   * 'User priority' is the nice value converted to something we
   * can work with better when scaling various scheduler parameters,
   * it's a [ 0 ... 39 ] range.
   */
  #define USER_PRIO(p)		((p)-MAX_RT_PRIO)
  #define TASK_USER_PRIO(p)	USER_PRIO((p)->static_prio)
  #define MAX_USER_PRIO		(USER_PRIO(MAX_PRIO))
  
  /*
   * Convert nice value [19,-20] to rlimit style value [1,40].
   */
  static inline long nice_to_rlimit(long nice)
  {
  	return (MAX_NICE - nice + 1);
  }
  
  /*
   * Convert rlimit style value [1,40] to nice value [-20, 19].
   */
  static inline long rlimit_to_nice(long prio)
  {
  	return (MAX_NICE - prio + 1);
  }
  
  #endif /* _SCHED_PRIO_H */