| /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
| #ifndef _UAPI_LINUX_SCHED_TYPES_H |
| #define _UAPI_LINUX_SCHED_TYPES_H |
| |
| #include <linux/types.h> |
| |
| struct sched_param { |
| int sched_priority; |
| }; |
| |
| #define SCHED_ATTR_SIZE_VER0 48 /* sizeof first published struct */ |
| #define SCHED_ATTR_SIZE_VER1 56 /* add: util_{min,max} */ |
| |
| /* |
| * Extended scheduling parameters data structure. |
| * |
| * This is needed because the original struct sched_param can not be |
| * altered without introducing ABI issues with legacy applications |
| * (e.g., in sched_getparam()). |
| * |
| * However, the possibility of specifying more than just a priority for |
| * the tasks may be useful for a wide variety of application fields, e.g., |
| * multimedia, streaming, automation and control, and many others. |
| * |
| * This variant (sched_attr) allows to define additional attributes to |
| * improve the scheduler knowledge about task requirements. |
| * |
| * Scheduling Class Attributes |
| * =========================== |
| * |
| * A subset of sched_attr attributes specifies the |
| * scheduling policy and relative POSIX attributes: |
| * |
| * @size size of the structure, for fwd/bwd compat. |
| * |
| * @sched_policy task's scheduling policy |
| * @sched_nice task's nice value (SCHED_NORMAL/BATCH) |
| * @sched_priority task's static priority (SCHED_FIFO/RR) |
| * |
| * Certain more advanced scheduling features can be controlled by a |
| * predefined set of flags via the attribute: |
| * |
| * @sched_flags for customizing the scheduler behaviour |
| * |
| * Sporadic Time-Constrained Task Attributes |
| * ========================================= |
| * |
| * A subset of sched_attr attributes allows to describe a so-called |
| * sporadic time-constrained task. |
| * |
| * In such a model a task is specified by: |
| * - the activation period or minimum instance inter-arrival time; |
| * - the maximum (or average, depending on the actual scheduling |
| * discipline) computation time of all instances, a.k.a. runtime; |
| * - the deadline (relative to the actual activation time) of each |
| * instance. |
| * Very briefly, a periodic (sporadic) task asks for the execution of |
| * some specific computation --which is typically called an instance-- |
| * (at most) every period. Moreover, each instance typically lasts no more |
| * than the runtime and must be completed by time instant t equal to |
| * the instance activation time + the deadline. |
| * |
| * This is reflected by the following fields of the sched_attr structure: |
| * |
| * @sched_deadline representative of the task's deadline |
| * @sched_runtime representative of the task's runtime |
| * @sched_period representative of the task's period |
| * |
| * Given this task model, there are a multiplicity of scheduling algorithms |
| * and policies, that can be used to ensure all the tasks will make their |
| * timing constraints. |
| * |
| * As of now, the SCHED_DEADLINE policy (sched_dl scheduling class) is the |
| * only user of this new interface. More information about the algorithm |
| * available in the scheduling class file or in Documentation/. |
| * |
| * Task Utilization Attributes |
| * =========================== |
| * |
| * A subset of sched_attr attributes allows to specify the utilization |
| * expected for a task. These attributes allow to inform the scheduler about |
| * the utilization boundaries within which it should schedule the task. These |
| * boundaries are valuable hints to support scheduler decisions on both task |
| * placement and frequency selection. |
| * |
| * @sched_util_min represents the minimum utilization |
| * @sched_util_max represents the maximum utilization |
| * |
| * Utilization is a value in the range [0..SCHED_CAPACITY_SCALE]. It |
| * represents the percentage of CPU time used by a task when running at the |
| * maximum frequency on the highest capacity CPU of the system. For example, a |
| * 20% utilization task is a task running for 2ms every 10ms at maximum |
| * frequency. |
| * |
| * A task with a min utilization value bigger than 0 is more likely scheduled |
| * on a CPU with a capacity big enough to fit the specified value. |
| * A task with a max utilization value smaller than 1024 is more likely |
| * scheduled on a CPU with no more capacity than the specified value. |
| */ |
| struct sched_attr { |
| __u32 size; |
| |
| __u32 sched_policy; |
| __u64 sched_flags; |
| |
| /* SCHED_NORMAL, SCHED_BATCH */ |
| __s32 sched_nice; |
| |
| /* SCHED_FIFO, SCHED_RR */ |
| __u32 sched_priority; |
| |
| /* SCHED_DEADLINE */ |
| __u64 sched_runtime; |
| __u64 sched_deadline; |
| __u64 sched_period; |
| |
| /* Utilization hints */ |
| __u32 sched_util_min; |
| __u32 sched_util_max; |
| |
| }; |
| |
| #endif /* _UAPI_LINUX_SCHED_TYPES_H */ |