sched.h - execution scheduling (REALTIME)
The <sched.h> header shall define the sched_param structure, which
contains the scheduling parameters required for implementation of each
supported scheduling policy. This structure shall contain at least the
int sched_priority Process execution scheduling priority.
In addition, if _POSIX_SPORADIC_SERVER or _POSIX_THREAD_SPORADIC_SERVER
is defined, the sched_param structure defined in <sched.h> shall
contain the following members in addition to those specified above:
int sched_ss_low_priority Low scheduling priority for
struct timespec sched_ss_repl_period Replenishment period for
struct timespec sched_ss_init_budget Initial budget for sporadic server.
int sched_ss_max_repl Maximum pending replenishments for
Each process is controlled by an associated scheduling policy and
priority. Associated with each policy is a priority range. Each policy
definition specifies the minimum priority range for that policy. The
priority ranges for each policy may overlap the priority ranges of
Four scheduling policies are defined; others may be defined by the
implementation. The four standard policies are indicated by the values
of the following symbolic constants:
First in-first out (FIFO) scheduling policy.
Round robin scheduling policy.
Sporadic server scheduling policy.
Another scheduling policy.
The values of these constants are distinct.
The following shall be declared as functions and may also be defined as
macros. Function prototypes shall be provided.
int sched_getparam(pid_t, struct sched_param *);
int sched_rr_get_interval(pid_t, struct timespec *);
int sched_setparam(pid_t, const struct sched_param *);
int sched_setscheduler(pid_t, int, const struct sched_param *);
Inclusion of the <sched.h> header may make visible all symbols from the
The following sections are informative.
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.php .