include/uapi/linux/sched/types.h

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 #ifndef _UAPI_LINUX_SCHED_TYPES_H
   3 #define _UAPI_LINUX_SCHED_TYPES_H
   4
   5 #include <linux/types.h>
   6
   7 struct sched_param {
   8         int sched_priority;
   9 };
  10
  11 #define SCHED_ATTR_SIZE_VER0    48      /* sizeof first published struct */
  12
  13 /*
  14  * Extended scheduling parameters data structure.
  15  *
  16  * This is needed because the original struct sched_param can not be
  17  * altered without introducing ABI issues with legacy applications
  18  * (e.g., in sched_getparam()).
  19  *
  20  * However, the possibility of specifying more than just a priority for
  21  * the tasks may be useful for a wide variety of application fields, e.g.,
  22  * multimedia, streaming, automation and control, and many others.
  23  *
  24  * This variant (sched_attr) is meant at describing a so-called
  25  * sporadic time-constrained task. In such model a task is specified by:
  26  *  - the activation period or minimum instance inter-arrival time;
  27  *  - the maximum (or average, depending on the actual scheduling
  28  *    discipline) computation time of all instances, a.k.a. runtime;
  29  *  - the deadline (relative to the actual activation time) of each
  30  *    instance.
  31  * Very briefly, a periodic (sporadic) task asks for the execution of
  32  * some specific computation --which is typically called an instance--
  33  * (at most) every period. Moreover, each instance typically lasts no more
  34  * than the runtime and must be completed by time instant t equal to
  35  * the instance activation time + the deadline.
  36  *
  37  * This is reflected by the actual fields of the sched_attr structure:
  38  *
  39  *  @size               size of the structure, for fwd/bwd compat.
  40  *
  41  *  @sched_policy       task's scheduling policy
  42  *  @sched_flags        for customizing the scheduler behaviour
  43  *  @sched_nice         task's nice value      (SCHED_NORMAL/BATCH)
  44  *  @sched_priority     task's static priority (SCHED_FIFO/RR)
  45  *  @sched_deadline     representative of the task's deadline
  46  *  @sched_runtime      representative of the task's runtime
  47  *  @sched_period       representative of the task's period
  48  *
  49  * Given this task model, there are a multiplicity of scheduling algorithms
  50  * and policies, that can be used to ensure all the tasks will make their
  51  * timing constraints.
  52  *
  53  * As of now, the SCHED_DEADLINE policy (sched_dl scheduling class) is the
  54  * only user of this new interface. More information about the algorithm
  55  * available in the scheduling class file or in Documentation/.
  56  */
  57 struct sched_attr {
  58         __u32 size;
  59
  60         __u32 sched_policy;
  61         __u64 sched_flags;
  62
  63         /* SCHED_NORMAL, SCHED_BATCH */
  64         __s32 sched_nice;
  65
  66         /* SCHED_FIFO, SCHED_RR */
  67         __u32 sched_priority;
  68
  69         /* SCHED_DEADLINE */
  70         __u64 sched_runtime;
  71         __u64 sched_deadline;
  72         __u64 sched_period;
  73 };
  74
  75 #endif /* _UAPI_LINUX_SCHED_TYPES_H */