types.h (4558B)
- /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
- #ifndef _LINUX_SCHED_TYPES_H
- #define _LINUX_SCHED_TYPES_H
- #include <linux/types.h>
- #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 in nanoseconds
- * @sched_runtime representative of the task's runtime in nanoseconds
- * @sched_period representative of the task's period in nanoseconds
- *
- * 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.
- *
- * A task utilization boundary can be reset by setting the attribute to -1.
- */
- 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 /* _LINUX_SCHED_TYPES_H */