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 */ 76
