sched.h(7POSIX)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
sched.h — execution scheduling

SYNOPSIS

#include <sched.h>

DESCRIPTION
The <sched.h> header shall define the pid_t type as described in <sys/types.h>.

The <sched.h> header shall define the time_t type as described in <sys/types.h>.

The <sched.h> header shall define the timespec structure as described in <time.h>.

The <sched.h> header shall define the sched_param structure, which shall include the scheduling parameters required for implementation of each supported scheduling policy. This structure shall include at least the following member:

    int       sched_priority        Process or thread execution scheduling priority.

The sched_param structure defined in <sched.h> shall include the following members in addition to those specified above:

    int             sched_ss_low_priority Low scheduling priority for
                                          sporadic server.
    struct timespec sched_ss_repl_period  Replenishment period for
                                          sporadic server.
    struct timespec sched_ss_init_budget  Initial budget for sporadic server.
    int             sched_ss_max_repl     Maximum pending replenishments for
                                          sporadic server.

Each process or thread 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 other policies.

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:

SCHED_FIFO
    First in-first out (FIFO) scheduling policy.

SCHED_RR
    Round robin scheduling policy.

SCHED_SPORADIC
    Sporadic server scheduling policy.

SCHED_OTHER
    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_get_priority_max(int);
    int    sched_get_priority_min(int);
    int    sched_getparam(pid_t, struct sched_param *);
    int    sched_getscheduler(pid_t);
    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 *);
    int    sched_yield(void);

Inclusion of the <sched.h> header may make visible all symbols from the <time.h> header.

The following sections are informative.

APPLICATION USAGE
None.

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
<sys_types.h>, <time.h>

The System Interfaces volume of POSIX.1-2017, sched_get_priority_max(), sched_getparam(), sched_getscheduler(), sched_rr_get_interval(), sched_setparam(), sched_setscheduler(), sched_yield()

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .