PTHREAD_ATTR_GETSCHEDPARAM(3P)

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
pthread_attr_getschedparam, pthread_attr_setschedparam — get and set the schedparam attribute

SYNOPSIS

#include <pthread.h>

int pthread_attr_getschedparam(const pthread_attr_t *restrict attr,
    struct sched_param *restrict param);
int pthread_attr_setschedparam(pthread_attr_t *restrict attr,
    const struct sched_param *restrict param);

DESCRIPTION
The pthread_attr_getschedparam() and pthread_attr_setschedparam() functions, respectively, shall get and set the scheduling parameter attributes in the attr argument. The contents of the param structure are defined in the <sched.h> header. For the SCHED_FIFO and SCHED_RR policies, the only required member of param is sched_priority.

For the SCHED_SPORADIC policy, the required members of the param structure are sched_priority, sched_ss_low_priority, sched_ss_repl_period, sched_ss_init_budget, and sched_ss_max_repl. The specified sched_ss_repl_period must be greater than or equal to the specified sched_ss_init_budget for the function to succeed; if it is not, then the function shall fail. The value of sched_ss_max_repl shall be within the inclusive range [1,{SS_REPL_MAX}] for the function to succeed; if not, the function shall fail. It is unspecified whether the sched_ss_repl_period and sched_ss_init_budget values are stored as provided by this function or are rounded to align with the resolution of the clock being used.

The behavior is undefined if the value specified by the attr argument to pthread_attr_getschedparam() or pthread_attr_setschedparam() does not refer to an initialized thread attributes object.

RETURN VALUE
If successful, the pthread_attr_getschedparam() and pthread_attr_setschedparam() functions shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS
The pthread_attr_setschedparam() function shall fail if:

ENOTSUP
    An attempt was made to set the attribute to an unsupported value.

The pthread_attr_setschedparam() function may fail if:

EINVAL
    The value of param is not valid.

These functions shall not return an error code of [EINTR].

The following sections are informative.

EXAMPLES
None.

APPLICATION USAGE
After these attributes have been set, a thread can be created with the specified attributes using pthread_create(). Using these routines does not affect the current running thread.

RATIONALE
If an implementation detects that the value specified by the attr argument to pthread_attr_getschedparam() or pthread_attr_setschedparam() does not refer to an initialized thread attributes object, it is recommended that the function should fail and report an [EINVAL] error.

FUTURE DIRECTIONS
None.

SEE ALSO
pthread_attr_destroy(), pthread_attr_getscope(), pthread_attr_getinheritsched(), pthread_attr_getschedpolicy(), pthread_create()

The Base Definitions volume of POSIX.1-2017, <pthread.h>, <sched.h>

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 .