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 | #define SCHED_ATTR_SIZE_VER0 48 /* sizeof first published struct */ |
8 | #define SCHED_ATTR_SIZE_VER1 56 /* add: util_{min,max} */ |
9 | |
10 | /* |
11 | * Extended scheduling parameters data structure. |
12 | * |
13 | * This is needed because the original struct sched_param can not be |
14 | * altered without introducing ABI issues with legacy applications |
15 | * (e.g., in sched_getparam()). |
16 | * |
17 | * However, the possibility of specifying more than just a priority for |
18 | * the tasks may be useful for a wide variety of application fields, e.g., |
19 | * multimedia, streaming, automation and control, and many others. |
20 | * |
21 | * This variant (sched_attr) allows to define additional attributes to |
22 | * improve the scheduler knowledge about task requirements. |
23 | * |
24 | * Scheduling Class Attributes |
25 | * =========================== |
26 | * |
27 | * A subset of sched_attr attributes specifies the |
28 | * scheduling policy and relative POSIX attributes: |
29 | * |
30 | * @size size of the structure, for fwd/bwd compat. |
31 | * |
32 | * @sched_policy task's scheduling policy |
33 | * @sched_nice task's nice value (SCHED_NORMAL/BATCH) |
34 | * @sched_priority task's static priority (SCHED_FIFO/RR) |
35 | * |
36 | * Certain more advanced scheduling features can be controlled by a |
37 | * predefined set of flags via the attribute: |
38 | * |
39 | * @sched_flags for customizing the scheduler behaviour |
40 | * |
41 | * Sporadic Time-Constrained Task Attributes |
42 | * ========================================= |
43 | * |
44 | * A subset of sched_attr attributes allows to describe a so-called |
45 | * sporadic time-constrained task. |
46 | * |
47 | * In such a model a task is specified by: |
48 | * - the activation period or minimum instance inter-arrival time; |
49 | * - the maximum (or average, depending on the actual scheduling |
50 | * discipline) computation time of all instances, a.k.a. runtime; |
51 | * - the deadline (relative to the actual activation time) of each |
52 | * instance. |
53 | * Very briefly, a periodic (sporadic) task asks for the execution of |
54 | * some specific computation --which is typically called an instance-- |
55 | * (at most) every period. Moreover, each instance typically lasts no more |
56 | * than the runtime and must be completed by time instant t equal to |
57 | * the instance activation time + the deadline. |
58 | * |
59 | * This is reflected by the following fields of the sched_attr structure: |
60 | * |
61 | * @sched_deadline representative of the task's deadline |
62 | * @sched_runtime representative of the task's runtime |
63 | * @sched_period representative of the task's period |
64 | * |
65 | * Given this task model, there are a multiplicity of scheduling algorithms |
66 | * and policies, that can be used to ensure all the tasks will make their |
67 | * timing constraints. |
68 | * |
69 | * As of now, the SCHED_DEADLINE policy (sched_dl scheduling class) is the |
70 | * only user of this new interface. More information about the algorithm |
71 | * available in the scheduling class file or in Documentation/. |
72 | * |
73 | * Task Utilization Attributes |
74 | * =========================== |
75 | * |
76 | * A subset of sched_attr attributes allows to specify the utilization |
77 | * expected for a task. These attributes allow to inform the scheduler about |
78 | * the utilization boundaries within which it should schedule the task. These |
79 | * boundaries are valuable hints to support scheduler decisions on both task |
80 | * placement and frequency selection. |
81 | * |
82 | * @sched_util_min represents the minimum utilization |
83 | * @sched_util_max represents the maximum utilization |
84 | * |
85 | * Utilization is a value in the range [0..SCHED_CAPACITY_SCALE]. It |
86 | * represents the percentage of CPU time used by a task when running at the |
87 | * maximum frequency on the highest capacity CPU of the system. For example, a |
88 | * 20% utilization task is a task running for 2ms every 10ms at maximum |
89 | * frequency. |
90 | * |
91 | * A task with a min utilization value bigger than 0 is more likely scheduled |
92 | * on a CPU with a capacity big enough to fit the specified value. |
93 | * A task with a max utilization value smaller than 1024 is more likely |
94 | * scheduled on a CPU with no more capacity than the specified value. |
95 | * |
96 | * A task utilization boundary can be reset by setting the attribute to -1. |
97 | */ |
98 | struct sched_attr { |
99 | __u32 size; |
100 | |
101 | __u32 sched_policy; |
102 | __u64 sched_flags; |
103 | |
104 | /* SCHED_NORMAL, SCHED_BATCH */ |
105 | __s32 sched_nice; |
106 | |
107 | /* SCHED_FIFO, SCHED_RR */ |
108 | __u32 sched_priority; |
109 | |
110 | /* SCHED_DEADLINE */ |
111 | __u64 sched_runtime; |
112 | __u64 sched_deadline; |
113 | __u64 sched_period; |
114 | |
115 | /* Utilization hints */ |
116 | __u32 sched_util_min; |
117 | __u32 sched_util_max; |
118 | |
119 | }; |
120 | |
121 | #endif /* _UAPI_LINUX_SCHED_TYPES_H */ |
122 | |